A mathematical model of gas filtration in a highly porous body with random inhomogeneities under the evaporation conditions of a substance from a deepened surface is elaborated. Calculations using this model show that the inhomogeneities exert a pronounced influence on the angular distribution of escaping molecules. An account of this factor favors solving the problems of synthesis of highly efficient porous materials for thermal protection of objects against high-energy actions.
In turbulent heat transfer studies a system of equations has been derived for describing the breakup and coalescence of bubbles in a turbulent liquid flow. On the basis of it solution it is shown that the final probability distribution of gas bubbles depends on such parameters as the energy of a liquid velocity field, the length scale of turbulent fluctuations, and the mean gas content of a gas-liquid system.
A concept of the effectively penetrating medium (EPM) is suggested and numerically substantiated with an account of a rheological factor, calculation relations are established, which relate relative changes in flow rate-head characteristics with parameters of the generalized Shulman equations of rheological state, a viscoplasticity parameter, and a hydraulic diameter of the EPM which makes it possible to set forth new representations of blood rheology and physiological liquids.
On a level with the best world analogs a system of the early computer-aided diagnosis of mammary gland pathology by using heat parameters is worked out. The system is based on the noise-resistant algorithms of dynamic formation of invariant symptoms analyzed by an expert system. The design principles of a thermographic chamber of a new generation with high temperature resolution (up to 0.05 K) have been elaborated which provides unique possibilities for medical and technical diagnostics of objects.
A physical and mathematical model of thermal superadiabatic oxidation of phenol is developed with an account of the processes of its evaporation and condensation upon filtration in porous media.
It was laid down a foundation for the statistical theory of the X-ray back scattering radiation that permits to develop a new tomography system for revealing of material and products defects on the condition of one-side access to the object.
The mathematical basic principles of limited views and projection X-ray tomography, using maximal a priori knowledge for reconstruction of the intrinsic object's structure with flaws are created.
A mathematical model for the registration of dynamic indentation that permits to take into account the influence of the imperfection of tested surface upon the result of the determination of physical-mechanical characteristics of materials is developed.
It is determined that at remagnetization of ferromagnet by weak (the amplitude intensity is for one order less than the coercive force of a sample) exciting field and magnetization by d-c field the main part in the mechanism of forming the upper even harmonics of magnetic induction takes the nonlinearity of reversible processes of remagnetization. That allows to get the information about the parameters of defects of ferromagnets' structure.
The mechanism of increasing of sedimental steadiness of magnetic colloids solid phase under the influence of elastic oscillations of ultrasound frequency is established. It is shown, that the decreasing of sedimentation is caused by de-aggregate character of interaction of field and magnetic fluid.
The methodology of conjugate description of non-homogenous multiphase systems with mobile continuous or dispersed interface surfaces has been developed on the basis of software packages. By this methodology the analysis of the determining parameters of aero- and hydrospheres interaction has been carried out in the problems of forecasting the estimations for ecosystems' evolution at nuclear and technogenous accidents, as well as a number of practical recommendations on operation of air systems of energy plants' cooling in the conditions of thermal and dynamic non-uniformity has been drawn up.
The choice of binary azeothropic mixtures of ozone-safe refrigerants as substitution for ozone-destructive refrigerants has been justified and for the first time the complex of their properties has been studied, such as heat conduction, viscosity, speed of sound, density, saturation line, as well as their compatibility with construction materials and capacitor oils. Mathematical models for the whole complex of the properties of the mixtures investigated have been developed.
An one-of-a-kind experimental plant with the capacity of 1400 kW has been created, where the passive safety system for nuclear reactors cooling ensuring the increasing of maximum capacity of heat removal by a factor of 5 has been modulated. The investigations carried out in special test regimes showed a good agreement between experimental and calculated data. The insensitivity of the system of accidental cooling to the influence of extreme meteorological factors has been corroborated.
A high temperature plant for experimental study of melts' viscosity of various materials and elements of the cores of power plants has been created and is on operation. The operating temperature in the heater is up to 2750°C, the medium is vacuum or inert gases; the plant is equipped with automated system of control and data processing. The measurement of the viscosity of different materials and compositions have been carried out at the plant at the temperatures of to 2680°C, such as stainless steel X18H10T, zirconium, nickel, copper, molybdenum, uranium dioxide and zirconium dioxide (UO2+ZrO2). The plant can be also used for experimental modeling of the processes of overheating in different energy equipment (the volume of the specimens is up to 100 cm3).
Instrumental X-gamma-spectrometric method for determining the content of transuranium radionuclides in soils, contaminated in a result of nuclear explosions and accidents at the plants operating on nuclear fuel, has been developed. The method has been justified when investigating the content of transuranium elements in soils samples, contaminated with a-irradiated nuclides and taken from Semipalatinsk test ground (Kazakhstan) and in Kyshtym region (Russia).
The interconnection of vibrational and loading characteristics of aggregates and systems of technological installation at process of their functioning has been explored. The main control principles and algorithms for performing the resource reliability testing have been worked out. The control systems of loading of working machine parts during reliability testing, reading and data processing of single and twoness randomness processes of information signals of parameters of working ability, that are characterized about the technical conditions of parts, have been designed and manufactured.
The further development ot the theory of design of working ability of mechanical systems have been received. There are worked out the methods of prognosis of characteristics of failure-free performance and longevity at hase of multi-level scheme of design, which imitate all conditions and working regimes, loads and interconnections between the elements of complex mechanical systems. The main design principles of testing and information unit of common databases and data banks of results of field testing have been formulated. These bases and banks can be used as information basis for valuation of quality level and reliability of machines during their design.
As a result of the study of dynamic processes at mechanical drives the analytical methods of value of efficiency of applying new design elements have been worked out. These methods give the possibility to receive the criterion of minimum vibroactivity, based at analysis of forms of natural oscillations of dynamic systems. Simultaneously the possibility for comparison of reliability values of different variants of design is provided.
The methodology of resource prediction at typical load conditions of load-carrier machine structures with account and computer modeling interconnection of stochastic processes of loading and accumulation of fatigue damages has been worked out. This approach was approbated and unified with methods of accelerated testing according to German standards and was recommended for using at testing centres of the Republic of Belarus and the Federative Republic of Germany.
A new hypothesis of localization of plastic deformation in modern ferrito-pearlite steels have been proposed. In accordance with the hypothesis the degree of nonhomogeneous macroplastic deformation is defined by irregularity concentration of copper near boundary volumes of grains. The minimum quantities of impurities of copper and nickel are estimated, at which presence the macrolocalization of plastic deformation at normalized or anneal ferrito-perlite steels and the Chernov--Luders deformation and destruction of sides of ferrite grain take place. For middle-carbon steels these quantities is nearly 0.15% of each element, and for low-alloyed magnesium steels is nearly 0.1%.
The law of influence of the temperature at strength of diamond powders have been investigated. It is established that the changing of diamond crystal morphology at result of heating is lead to significant lowering of their strength. The critical regimes of thermal treatment for different powders may be defined by the intensity of morphology changes. At heating a high quality diamond to 1300°C the cracking crystal on the blocks takes place, the mosaic structure at oval diamond is developed, the graphite oriented to diamond lattice is observed. The less perfection diamond powders is cracked more intensively. The presence of polycrystal graphite is observed at range volume of a whole crystal.
A method for calculation of nuclear energy systems incorporating the electronuclear breeders with proton accelerators and nuclear reactors has been developed. The optimum conditions for production of uranium-233 and burning-up of plutonium in the electronuclear breeder at the meet of power supply have been calculated.
A scheme for transmutation of long-lived radioactive waste of nuclear energetics in the accelerator driven systems has been developed. A possibility for decommissioning the plutonium from fuel cycle by using of its energetic potential for energy and fissile nuclides production in these systems has been shown.
The method of measurement of the distributions of fission densities of transuranium nuclei by the solid track nuclear detectors and the thin film breakdown counters has been developed for the experimental investigations of the interactions of high energy protons, deuterons and alpha-particles with the multicomponent targets.
A model describing the negative parity collective levels up to 3 MeV excitation energy (5 first rotational bands) was developed assuming nucleus to be even-even non-axial quadrupolly deformed, deformable rotator and taking into account rigid hexadecapole surface models. The Hamiltonian developed was used to build strong coupling scheme for scattering and gamma-ray transition data calculation, that allowed to improve the experimental data description.
The model of radiolysis of the multicomponent gas mixture based on humid air with an admixture of NO and NO2 by accelerated electrons in electric field has been developed. The chain processes based on electron was demonstrated to take place under such conditions. This produces the efficient increasing of active particle to respond for oxidation SO to H2SO4 and restoration NO to NO2, in so doing these processes are realized in the area of low dose (<5·1014 eV/cm3).
Original method, algorithm and computer code are developed for calculation of energy deposition in a target, as well as for calculation of thermodynamical and hydrodynamical parameters of the target irradiated by high energy electron beams. It was shown that the current of thermalized electrons and spatial charge induced in the target by fast electrons of incident high current beam influence significantly on spatial and time distribution of energy losses of incident fast electrons. The computer code is implemented on PC and enables one to calculate also the change of thermodynamical parameters of solids due to charge particles irradiation.
Methods for determination of radioecological damage of the territory of Belarus in the conditions of accidents at radiation-dangerous objects have been suggested. The methods and criteria for optimization of the strategy of activities in such conditions have been created, the optimal conditions for decontamination of the contaminated territories have been determined. The original data for restoration of the exposure doses received by residents of the Republic in the initial period of the Chernobyl accident have been determined.
The analysis of contamination of the air basin of 12 cities and 6 areas of Belarus with use of the accumulated data on the discharges of the stationary sources of industrial enterprises and objects of energetics has been carried out. The ecologically dangerous zones of the populated areas in respect to the excess of the content of the detrimental substances in the atmosphere over the permissible norms have been found out. For regions contaminated with radionuclides the ecological situation is evaluated according to the complex of radiation-chemical contamination. The method of evaluation of the priority of carrying out the protective measures at contaminated territories, taken as the basis of the creation of the decision making system for decontamination of the populated areas, has been developed. The developed complex of the information base is used by the nature protection authorities for the control over the state of the atmosphere and planning the nature protection measures.
The experimental investigations of the dependence of 137Cs distribution in the upper layer of the soil of 10 cm thickness on the value of the size across of the soil particles have been conducted. It has been found out that the main fraction of the volumetric activity (50--55%) is concentrated in the particles with the particle sizes of 0.05--0.005 mm across.
The investigations of the possibilities for fixation of radiostrontium in the soils with the ratio of the components in the system of solid phase -- liquid equal to 1:10 have been carried out. Various compounds have been used as the fixing reagents. It has been shown that the introduction of phosphates into soils in the quantity of 0.2--1 mg per 1 g of soil results in fixation of 25--82% of 90Sr. The natural mineral tripel doesn't possess the fixation effect. The phosphates have acted most effectively in the soils with the minimum content of clay. Thus, the sod podzol soil, which contains 17.2% of clay fixes 81.5% of 90Sr. In the sod soils, containing 27--28% of clay, 23.4--37.7% of radiostrontium are fixed. The sand doesn't effect the change of the content of mobile forms of radiostrontium in the studied soils. The data received support the possibilities for obtaining the clean agricultural products at the contaminated with radionuclides territories and the possibilities of restoration of agricultural areas.
A technology of generating the multi-layer high-thermoconductivity coatings having high wear and corrosion resistance is developed. The protective and wear properties of these coatings permit 5--12 times increase of the corrosion and wear resistance of metals and their alloys as compared with those obtained by the traditional methods.
The development was made of the theory of orbital quantum-exposed, vortex states of a laser-irradiation electromagnetic field. The spiral laser beams expanding in nonlinear media were shown to be the orbital quantum-exposed excitations of a photon Bose-condensate. As physical phenomena they are identical to both quantum vortex lines in a superfluid helium and the Abrikosov vortex lines in the second-type semiconductors. A superfluid state of a photon Bose-condensate was proved to exist in an active substance of some lasers the orbital quantum-exposed excitations of which correspond to regeneration modes of a spiral orbital irradiation. It was also shown that a topological charge of a spiral laser beam coincided with an orbital quantum number of orbital spiral photons of a vortex electromagnetic field. The formation processes of optical vortices with various topological charges as well as those of multi-vortex structures of laser-system light fields were studied numerically and analytically.
The structure and decorative properties of ion-plasma titanium oxide coatings were subjected to investigation. It was established that the most important technological parameter which determined a type of a polymorphous modification and compound lattice parameters was a partial gas reagent pressure. The latter growth led to that oxide lattice parameters changed tending to attain a stoichiometric composition with subsequent a new phase realization. In this case a costing was a monophase (TiO or TiO2) or a phase mixture (Ti2O3+TiO2) depending on the value of the above mentioned technological parameter. Based on the results of spectrophotometric measurements the color and coloration coordinates of these coatings were calculated and a correlated relationship was established between a phase composition of condensates and their color parameters.
The theoretical and technological foundations for a creation of armor gradient materials and multilayer composite systems were developed. The calculation of concentration redistribution of alloying components made for bimetallic Ti--Al and Fe--Al systems provided the basis for determination of the temperature-speed processing parameters the use of which helped to avoid the formation of an intermetallic layer of a critical thickness in boundary zones.
The analysis of state of art of a computer animation was carried out. The methods of contracting separate stills were developed on the base of a picture approximation using a net of triangles with Gyro painting (triangulation). They allowed achievement of contraction degrees comparable with JPEG contraction results and in contrast to the latter enabled presentation of information in a vector form.
The physical-chemical properties of low-melting polyethylene terephthalate (PETP) have been studied. It has been found out that by the character of the main phase transitions it is analogous to high-molecular PETP but has a wider range of processing temperatures. By a number of characteristics, e.g. such as tensile strength and elongation strength, it is superior to high-molecular polymers, but by chemical resistance (upon endurance in alkali and acids) it is somewhat inferior (by 10--12%). Technological properties of low-melting dispersed PETP have been determined (using the method of grinding in disintegrator). It is shown that according to its main parameters (looseness, electrifiableness, fluidizability, etc.) the material can be used in various methods of powder technique.
Spreading of diethyleneglycol and glycerin viscous liquids over pentaplast electret films surface has been studied. The dependence has been investigated of a liquid drop spread velocity and edge wetting angle on the electret charge of the film. It is shown that the film polarization and growth of the electret charge (thermal and corona electrets) lead to the decreased initial velocity of spreading and to reduction of the actual contact between the drop and the film. A mathematical model is suggested which permits to consider the electret charge effect on kinetic characteristics of a liquid spreading over the electret polymer film surface.
Debris formation kinetics has been studied under the polymer materials friction. A periodical character has been established of fatigue microcracks propagation in the surface layer of the wearing material. The periods of microcracks growth alternate with a prolonged stable period or that of their size reduction. The behavior of fatigue processes and the mechanism of debris formation are determined by the amplitude values, correlation of deformation tensor components, as well as by the level of temperature gradient on the contact local areas. The results obtained are the basis for constructing a model of polymer materials wear.
The effect of the absorbed dose on adhesive properties of block HDPE gamma-radiated in the air up to 4 Mrem has been investigated. For the first time, it was shown by direct experiments using the method of sequential microsoaking that the maximum values of adhesive strength were reached in the subsurface layer at a depth of 60--120 µm with general monotonous variations of the material physical-chemical state up to 400 µm depth from the surface. It was found out that the highest values of adhesion correspond to the optimum correlation between polar oxygen-containing groups concentration and density of intermolecular covalent bonds.
A complex approach to strength estimation of heterogeneous composites is proposed based on boundary elemental and finite elemental approximations. The method permits to simplify determination of boundary conditions at the interface and to describe inhomogeneous structure of a medium taking into account nonlinear effects in the material microvolumes. The method developed represents iteration of variational inequality solution which describes contact interaction of material blocks and estimation of arbitrary shaped microblocks deformation by the finite element method. The present method is used to define the stress state and strength of frictional joints and composite coatings of structural parts.
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A technology of manufacturing of thin silver films for usage as substrates for investigation of the enhanced Raman scattering of complex molecular objects has been developed. The analysis of the influence of thin silver films surface roughnesses on the parameters of enhanced Raman scattering of rodamine R6G at different distances to surface was carried out. It has been shown that special thermal processing of thin silver films has led to forming of near regular island film structure that significantly increases the action distance of the enhanced Raman scattering. (In cooperation with the Ya.Kupala Grodna State University.)
The calculation method of dissipative warm segregation owing to friction forces action on the contact surface of high filled press-composition with working walls of extrusion device have been developed. At the example of wood press-composition the power calculation for screw, cylinder, and forming equipment was carried out.
A technology for obtaining the high-purity cholesterol from meat-packing factory wastes (the cattle corn) has been developed. The technology excludes the usage of harmful and dangerous chemical substances.
By liquid lithography the sensible elements of infrared radiation bolometers on the base of HTSC-films of Y-Ba-Cu-O system were formed. The investigation of the characteristics of IR-bolometer with sensible elements in form of meander having band size from 10 up to 50 mm has demonstrated that, in dependence of HTSC-films and meander forming technology, the principal parameters of IR-bolometers formed on monocrystalic silicon substrates with zirconium dioxyde sublayer vary in next limits: the volt-watt sensibility ranges from 102 to 104 V/W and time constant varies between 80 and 0.8 ms. It is found that for bolometrs working in isothermic mode the degree of structural perfection has influence on noise tension and time constant. For IR-bolometers working in non-equilibrium mode (formed on the basis of HTSC-films and having the semiconductive type of resistance dependence from temperature in normal condition) the volt-watt sensibility in optical range is 2 or 3 time higher than for those ones working in the equilibrium mode. The dependencies of IR-bolometeres time constant from heat physical properties and acoustic concordance of the boundary HTSC-film-substrate has been also revealed.
The resistive properties of diamond-like carbon films (DLCF) produced on plates from anodic Al2O3 by the method of pulse plasma condensation with simultaneous assisting by argon ions have been investigated. The study of DLCF resistive properties was made in the open air under room temperature after preliminary two-hour exposition in vacuum stove under the fixed temperatures T=300--800°C at every 100°C. It is indicated that up to T=500°C the film resistance changes relatively slow. In the range from 500 to 700°C there was observed a fast resistance reduction from hundreds MOhm/square up to some KOhm/square. The resistance is stabilized at the level of some KOhm under T>700°C. The electrical resistance in all annealing temperatures range is greatest for films produced under more high discharge voltages. This is conditioned by increase of quantity of sp3 hybridized carbon atom bonds during growth of energy of carbon plasma ions. The DLCF retain the resistance more than 100 MOhm/square after annealing under 600°C. By the elastically strained systems thermodynamic analysis it was shown that there is the critical temperature of film heating under which the lateral tensions decrease up to sense under which the sp3 bond become unstable, the graphitization of diamond-like films takes place and as the result their electrical resistance decreases sharply.
Conception of creation and methodology of investigation of the perspective mobile machines on the basis of system approach are worked out. Providing the machines' conformity to the basic exploitation and consumer characteristics and also production requirements are taken into consideration. A new direction is suggested of the mobile machines theory based on the control of the mobile machines' exploitation characteristics and algorithm realization of this decision.
A theoretical basis for analysis of the loading and summing up of damage of the constructions' elements of the mobile machines under many-frequency exploitation loading is worked out. The conception of methods of standard wear-fatigue material tests has been elaborated; the methods indicated are being realized on the C test machines which are being built up.
A complex of the control, informational-diagnostic and service electronic systems for automobiles and tractors is worked out. The complex consists of the system of break's regime control and wheels' slipping, the system of control of the suspensions of MAZ automobiles and autotrains, the electronic informational instrument for the MTZ tractors (a total of about 15 systems).
A method for spectral signal analysis with the constant trigonometric coefficients for its every harmonic element is proposed. The method increases the frequency bandwidth of real time random signal processing up to ten times. A modified algorithm of random search based on the best sample among the mean values of all ones is developed. Application limits of it for vehicles' vibration system are defined.
Source: "Main Results of Fundamental Research.1995". Eds. A.M.Goncharenko and N.N.Kostyukovich. Academy of Sciences of Belarus, Minsk, 1996
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