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Загальна кількість знайдених документів : 19 Представлено документи з 1 до 19 |
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| 1. | 
Dovbeshko G. I. Secondary emission from synthetic opal infiltrated by colloidal gold and glycine [Електронний ресурс] / G. I. Dovbeshko, O. M. Fesenko, V. V. Boyko, V. R. Romanyuk, V. S. Gorelik, V. N. Moiseyenko, V. B. Sobolev, V. V. Shvalagin // Ukrainian journal of physics. - 2012. - Vol. 57, № 2. - С. 154-158. - Режим доступу: http://nbuv.gov.ua/UJRN/Ukjourph_2012_57_2_11 Проведено порівняльний аналіз вторинної емісії (фотолюмінесценції) та брегівського відбивання фотонних кристалів (синтетичних опалів), інфільтрованих колоїдним золотом, гліцином і комплексом колоїдного золота з гліцином. Інфільтрація колоїдного золота та його комплексу з гліцином в пори фотонного кристала призвела до короткохвильового (на 5 - 15 нм) зсуву максимуму брегівського відбиття та зростання його інтенсивності в 1,5 - 3 рази. У фотолюмінесценції інфільтрація колоїдного золота та комплексу колоїдного золота з гліцином у пори фотонного кристала призводить до пригнічення смуги поблизу 375 - 450 нм і підсилення смуги поблизу краю стоп-зони на 470 - 510 нм. Форма смуги фотолюмінесценції опалу, що викликана його дефектами та домішками, визначається довжиною хвилі збуджуючого випромінювання та типом інфільтрату. Розглянуто можливі механізми ефектів, що спостерігаються. | ||
| 2. | 
Dovbeshko G. I. Secondary emission from synthetic opal infiltrated by colloidal gold and glycine [Електронний ресурс] / G. I. Dovbeshko, O. M. Fesenko, V. V. Boyko, V. R. Romanyuk, V. S. Gorelik, V. N. Moiseyenko, V. B. Sobolev, V. V. Shvalagin // Український фізичний журнал. - 2012. - Т. 57, № 2. - С. 154-158. - Режим доступу: http://nbuv.gov.ua/UJRN/UPhJ_2012_57_2_11 Проведено порівняльний аналіз вторинної емісії (фотолюмінесценції) та брегівського відбивання фотонних кристалів (синтетичних опалів), інфільтрованих колоїдним золотом, гліцином і комплексом колоїдного золота з гліцином. Інфільтрація колоїдного золота та його комплексу з гліцином в пори фотонного кристала призвела до короткохвильового (на 5 - 15 нм) зсуву максимуму брегівського відбиття та зростання його інтенсивності в 1,5 - 3 рази. У фотолюмінесценції інфільтрація колоїдного золота та комплексу колоїдного золота з гліцином у пори фотонного кристала призводить до пригнічення смуги поблизу 375 - 450 нм і підсилення смуги поблизу краю стоп-зони на 470 - 510 нм. Форма смуги фотолюмінесценції опалу, що викликана його дефектами та домішками, визначається довжиною хвилі збуджуючого випромінювання та типом інфільтрату. Розглянуто можливі механізми ефектів, що спостерігаються. | ||
| 3. | 
Sobolev V. V. On formation of electrically conductive phases under electrothermal activation of ferruginous carbonates [Електронний ресурс] / V. V. Sobolev, N. V. Bilan, A. V. Khalymendyk // Науковий вісник Національного гірничого університету. - 2017. - № 4. - С. 27-35. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2017_4_6 Purpose. Study of the formation of an electrically conductive phase in carbonates using siderite as an example and determination of the temperature dependence of its formation and silicon content during simultaneous heating and the action of a weak electric field. Methodology. Analysis and generalization of the results of experimental studies. Physicochemical analytical studies have been performed using electron and optical microscopy, petrographic and X-ray phase analysis, thermogravimetric analysis and differential scanning calorimetry, and gas chromatography. Phase equilibria in the "iron oxides - carbon - carbon oxides" system have been evaluated using data on the standard change in the Gibbs energy Evaluation. Findings. Formation of electrically conductive phases in siderite has been studied. The dependence of new phase formation on heating and the magnitude of the electric field strength have been determined. The regularities of the change in threshold temperatures of phase transitions in samples of siderite and calcite containing silicon impurities have been established. Originality. Due to the thermally stimulated increase in the concentration of mobile charge carriers in intergranular space, the electric field of point charges takes the prominent part in the formation of the end product of chemical reactions. The additional effect of electric current on the increasing destabilization of chemical bonds between surface atoms leads to the formation and transport of ions, to a decrease in the energy barrier of nuclei formation of the electrically conductive phase near the active centres. The abrupt increase in electrical conductivity is due to the spontaneous formation of the nuclei of a new phase and the transition of ionic conductivity to a mixed one or an electronic one primarily. A composite semiconductor is formed as a result of electrothermal activation of siderite. This semiconductor consists of a matrix-semiconductor representing the initial mineral and is penetrated by parallel-oriented high-conductivity threads. Practical value. Experimental results show that such processes occurring in rock are quite real under the conditions of the earth's crust, and the physical values of thermodynamic quantities (factors of metamorphism) are sometimes overestimated significantly in the interpretation of various geological events. | ||
| 4. |
Sobolev V. V. Mechanism of thick metal walls penetration by high-speed microparticles [Електронний ресурс] / V. V. Sobolev, O. S. Baskevych, L. M. Shyman, S. M. Usherenko // Науковий вісник Національного гірничого університету. - 2016. - № 6. - С. 75-83. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2016_6_11 Purpose. Analysis and estimation of physical parameters which create conditions for microparticles penetration into metal microstructure to abnormally big depth. Methodology. Quantum mechanical three-site model has been used for studying the regularities of electron motion in the field of two Coulomb centres and numerical solution for the problem of the effect of external electrical charge on stability of the chemical bond. Solution was found for the equation of heat conductivity for estimating the temperature of microparticles heating under compression and acceleration by explosively driven accelerator. Stokes's law was used for estimating viscosity of hypothetical medium which can be penetrated by microparticle at a great speed and to a great depth. The research was done with the help of X-ray microanalysis, X-ray crystallography, micrographic investigation, mass-spectrometry and electronic spectroscopy. Findings. Solution of the quantum mechanical model testifies that electric charges serve as catalysts responsible for the significant reduction of the energy barrier of chemical reactions. To ensure super deep penetration, it is necessary to achieve acceleration of a great number of microparticles in a special explosively driven accelerator. Heating, intensive stirring and friction result in electrification of the surface of the particles, which is known as triboelectric effect. The hypothesis about physical and chemical mechanism of particles penetration into metals resulting from high-speed impact has been put forward. Originality. The research has established relationship between the sizes of microparticles accelerated by explosion and the density of electric charges on their surfaces, as well as the depth of their penetration into the metal barrier. By experimental research, it was proven that maximum depth of microparticles penetration is directly proportional to the maximum density of surface charges for the particles of the 50 - 80 <$Emu>m size. It is assumed that particles penetration into metals to greater depths is conditioned by the reduction of the barrier material viscosity in the zone of particle-barrier contact due to quantum mechanical effects in the solid-state plasma. Practical value. The value of the work includes creating a new generation of metal composites as well as new prospective technologies of reactive materials utilization. | ||
| 5. |
Sobolev V. V. Computational modeling in research of ignition mechanism of explosives by laser radiation [Електронний ресурс] / V. V. Sobolev, L. M. Shyman, M. M. Nalysko, O. L. Kyrychenko // Науковий вісник Національного гірничого університету. - 2017. - № 6. - С. 53-60. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2017_6_10 Purpose. To give a theoretical description of laser propagation in energy-saturated photosensitive composites as in diffuse scattering media with close packed scatterers. Methodology. Analysis and generalization of theoretical research. The Monte Carlo method of direct statistical modeling has been applied. A computational study of the process of scattering of photons in photosensitive energy-saturated composites has been carried out, the results of the computational study have been analyzed. Findings. The results of computation of the illuminance for diffuse scattering media (DSM) by the Monte Carlo method have been presented. In particular, it has been determined that the initiation of highly sensitive explosives and photosensitive composites can not be explained based on the concepts of a multiple increase in volumetric illumination within a diffuse scattering medium with respect to the surface one, since such an increase is unfeasible. However, the light regime in a diffuse scattering medium is one of the determining factors for the ignition of explosives by laser radiation. Originality. The diffuse reflection factor of DSM mainly depends on the photon survival rate and the refraction index. For each DSM there is a limiting value of the laser beam radius beginning with which the spatial illuminance does not change with the increase in the laser beam radius r. It is shown that with the increase in the bunch concentration in samples of photosensitive explosives (VS), the depth of the material layer with high values of illuminance increases. Moreover, the growth rate is inversely proportional to the beam radius. This regularity is well correlated with observed experimental dependence of VS sensitivity on the bunch concentration. Thus, in case of initiation of substance of VS2 grade with a 1,5 mm diameter laser beam, the sensitivity increased approximately by a factor of 2 with an increase in the bunch concentration from 10 to 20 - 30 %, while for a 4,5 mm diameter beam the sensitivity growth was ~ 13 %. Practical value. The results of theoretical research were used when making laboratory samples of the optical detonator and during the research on actuation of optical detonators depending on the energetic and geometric characteristics of the laser beam. | ||
| 6. |
Sobolev V. V. The macrokinetics parameters of the hydrocarbons combustion in the numerical calculation of accidental explosions in mines [Електронний ресурс] / V. V. Sobolev, Ye. B. Ustimenko, M. M. Nalisko, I. L. Kovalenko // Науковий вісник Національного гірничого університету. - 2018. - № 1. - С. 89-98. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2018_1_14 Purpose. Obtaining effective parameters of the macrokinetics of combustion of hydrocarbons in the deflagration and detonation regime for the numerical calculation of emergency explosions in mine workings. Methodology. Mathematical modeling, numerical experiment, kinetics analysis of explosive combustion reaction, analysis and synthesis. Findings. The paper analyzes the parameters of the kinetic equation against experimental data. Obtaining such data in a physical experiment for explosive chemical reactions meets serious difficulties. This is due to the size of the reaction zone not exceeding fractions of a millimeter, the lack of time resolution of experimental techniques and other factors leading to errors in direct measurements and the emergence of multiple solutions. This possibility contributes to obtaining a simultaneous numerical solution of the equations of gas dynamics and chemical kinetics. In the numerical experiment, a direct relationship between the macrokinetic characteristics of the chemical reaction and the parameters of the discontinuous flow of the reacting gas stream is established: velocity, pressure in the front and behind the front of the detonation and deflagration wave. Based on this, Arrhenius characteristics of the reaction - pre-exponential and effective activation energy for the hydrocarbons under consideration are obtained. Originality. Macrokinetic parameters are established for simulating one-stage ignition and burning of the most probable hydrocarbons of the mine atmosphere in the deflagration and detonation regime. Modeling of explosive combustion of premixed hydrocarbons in stoichiometric concentrations is performed. It is shown that the values of the effective activation energy in explosive combustion reactions are of less importance in contrast to steady-state combustion reactions because of the effect of the gas-dynamical effects of the shock wave on the reaction rate. The Arrhenius characteristics of the reaction - the pre-exponential and the effective activation energy - have been agreed upon, according to the gas dynamic and kinetic parameters of the course of the explosive combustion reaction. Practical value. The obtained parameters of the macrokinetics of the explosive combustion reaction make it possible to apply simple kinetic mechanisms in practical calculations of the processes of deflagration and detonation combustion, and to predict the parameters of emergency explosions in conditions of mine workings with sufficient accuracy. This also makes it possible to solve the problem of accounting for the presence of heavy hydrocarbons in the mine atmosphere as products of coal pyrolysis in underground fires as factors of increasing the risk of emergency explosions. | ||
| 7. |
Sobolev V. V. Electrical charges as catalysts of chemical reactions on a solid surface [Електронний ресурс] / V. V. Sobolev, N. V. Bilan, O. S. Baskevych, L. I. Stefanovich // Науковий вісник Національного гірничого університету. - 2018. - № 4. - С. 50-58. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2018_4_9 Purpose. To determine the change dependency of the potential energy of the chemical bond of a diatomic molecule on the value of the point charge and its distance to the bond using quantum mechanical calculation. Methodology. Numerical simulation of a quantum mechanical system consisting of a point charge and a diatomic molecule interacting with each other. Findings. The quantum-mechanical problem of the effect of an external Coulomb center on the chemical bond of diatomic molecules is solved. Originality. A quantum mechanical model of a physical system consisting of three interacting Coulomb centers (there is a chemical bond between two of them) is developed. The model makes it possible to understand the dynamics of the interaction of a molecule with an ion, the charge of which can be characterized by either integers or fractional numbers. The change in the energy of the chemical bond in the ion field depending on the distance to the bond and the magnitude of the charge is established. Practical value. The developed technique for calculating the energy of a chemical bond as a function of the magnitude of the electric charge was used in the development of the method for growing single crystals of metastable diamond, in calculating the limits of the chemical bond stability in metal azides, in developing the way of additional harmful gases formation during rock blasting and in calculating the stability of nanoscale hydrocarbon chains in coal, and others. The method can be used to decide on the catalyst and control the catalytic reactions. | ||
| 8. |
Sobolev V. V. Physical conditions of the ‘light’ core formation and thermonuclear heat source deep inside the earth [Електронний ресурс] / V. V. Sobolev, N. V. Bilan // Науковий вісник Національного гірничого університету. - 2018. - № 5. - С. 13-23. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2018_5_4 Purpose. Experimental research into the physical model of the Earth's core formation in the center of gas-dust spiral vortex and numerical assessment of the physical conditions associated with the development of thermonuclear reactions in the Earth's core. Methodology. Analysis of the main points of conventional conceptions, their principal merits and drawbacks which delineate their potential possibilities. Experimental studies implementing shock-wave treatment of porous materials in cylindrical containers. Numerical assessment of the physical conditions that initiate thermonuclear reactions in the Earth's core. Findings. It is extremely important to choose the model of the Earth formation with originally "light" core for several reasons. First, it provides a physically grounded mechanism of the thermonuclear heat source formation; second, the process of the Earth transition to equilibrium state inevitably creates conditions for mechanical, physical and chemical activity of elements in geospheres. Numerical assessment was performed to estimate the main conditions which are necessary for thermonuclear heating of the Earth's central bulk - to determine the deuterium nuclei concentration and the respective temperatures. Originality. The authors suggested a model describing formation of the initially "light" core of the Earth. Experiments allowed studying some physical peculiarities of spiral vortices initiation and development. Regularities of change in plasma parameters, core temperature and thermonuclear energy release have been established in reference to the Earth's age. Practical value. The obtained results will be useful for studying such important planetary geological phenomena as matter differentiation and formation of spheres inside the planet, as well as heat flow distribution in its bulk. | ||
| 9. | 
Sobolev V. A. Practical approach to environmentally safevital activity in modern conditions [Електронний ресурс] / V. A. Sobolev // Вчені записки Таврійського національного університету імені В. І. Вернадського. Серія : Технічні науки. - 2017. - Т. 28(67), № 2. - С. 55-63. - Режим доступу: http://nbuv.gov.ua/UJRN/sntuts_2017_28_2_14 | ||
| 10. |
Sobolev V. V. Physical and chemical transformations in gas coal samples influenced by the weak magnetic field [Електронний ресурс] / V. V. Sobolev, D. V. Rudakov, O. N. Molchanov, L. I. Stefanovych, A. K. Kirillov // Науковий вісник Національного гірничого університету. - 2019. - № 6. - С. 52-58. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2019_6_10 Purpose. To study changes in the gas coal sample microstructure, the trends of changing iron concentration and thermal effects of chemical reactions stimulated by the pulsating magnetic field of low intensity. Methodology. This study used the experimental research methodology, mathematical treatment of the results and analytical methods including X-ray fluorescence spectroscopy, differential thermal and thermogravitational analysis, X-ray diffraction analysis and coal microparticles distribution by fractions, and others. Findings. Treatment of gas coal samples with weak magnetic and electric fields showed that destructive processes in coal can be initiated both by electric and magnetic fields of weak density. The phase transitions and thermal effects in coal under changing temperature, coal mass changes during heating were defined; temperatures of exothermic and endothermic processes and the enthalpy of new substance formation were evaluated. The microparticle size distribution depending on the treatment method was analyzed. Originality. It was shown that the iron concentration in recovered gas coal increases with decreasing the grain microparticle size to a limit value corresponding to the iron ash concentration. As a result of the influence of a low intensity pulsating magnetic field strength on the pre-mechanically activated carbon microstructure, the microparticle size increases and, in general, their size range significantly expands. The minimum amount of absorbed heat is required for the chemical compound formation in mechanically activated coal, and the maximum amount is needed for mechanical activation followed by magnetic field treatment that, in the latter case, can be related to additional implementation of spin-selective chemical reactions directly on the coal microparticle surfaces. Practical value. The obtained experimental results emphasize the fact that weak magnetic fields actively participate in coalification. The results of experimental research can be used in the development of magnetic methods for coal outburst suppression. | ||
| 11. |
Sobolev V. V. Evaluation of blast wave parameters within the near-explosion zone in the process of rock breaking with borehole charges [Електронний ресурс] / V. V. Sobolev, V. V. Kulivar, O. L. Kyrychenko, А. V. Kurliak, О. O. Balakin // Науковий вісник Національного гірничого університету. - 2020. - № 2. - С. 47-52. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2020_2_10 Purpose. To analyse the experimental results, to describe physical mechanism of blasted rock disintegration and develop methodology to calculate blast-wave parameters within the near-explosion zone, and to study possible role of thermoelastic stresses in rock fragmentation to ultradisperse fractions in the near-explosion zone. Methodology. The experiments involved a method to measure dynamic compressibility of bituminous coals based on the determination of both velocity of blast waves and mass velocity of particles beyond the front. A reflection method is used to construct isentropes of the explosive detonation products and their impact adiabat. Findings. Experimental studies are carried out to analyse compressibility parameters of bituminous coals - blast wave velocity and mass velocity of particles beyond the blast wave front. Impact adiabats for emulsion explosive ЕРА Р-3 and bituminous coals are constructed. A set of theoretical studies is performed. Originality. Methodology to evaluate blast-wave parameters within the zone near the borehole or blasthole charge explosion is proposed. Physical mechanism for rock breaking to ultradisperse particles is proposed. It has been specified that thermoelastic stresses may be one of the possible causes, if not the main one, of the rock breaking within the near-explosion zone. A mechanism stipulated by the transition of microstructure of the rock crystalline components to the instable state is considered as the alternative (or additional) factor. The cause is in the oversaturation of the rock microstructure with the linear and point defects. Exceeded value of critical concentration of those defects results in the excessive reserves of internal energy with the following spontaneous breaking of chemical bonds. Impact adiabats of coking coals of three grades as well as isentrope and impact adiabat of the detonation products of emulsion explosive ЕРА Р-3 are constructed. In terms of the "pressure - mass velocity of particles" coordinates, curves of adiabats of the bituminous coals differ by not more than 4 %. Practical value. Analysis of the scientific results may be the required condition to develop additional safety measures in the sphere of environmental protection during blasting operations in terms of open-pit and underground mining. | ||
| 12. |
Sobolev V. V. Influence of mechanical and thermal treatments on microstructural transformations in cast irons and properties of synthesized diamond crystals [Електронний ресурс] / V. V. Sobolev, S. I. Gubenko, D. V. Rudakov, O. L. Kyrychenko, O. O. Balakin // Науковий вісник Національного гірничого університету. - 2020. - № 4. - С. 53-62. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2020_4_10 Purpose. To analyze how the structural transformations in the cast iron metal matrix near graphite inclusions influence the features of synthesis of metastable diamond crystal on diamond polycrystals (substrate) synthesized by shock-waves. Methodology. In experiments, we used the laser-induced detonation of explosive charges to create a flat shock-wave front and employed chemical, microstructural, spectral and X-ray phase analyzes. In particular, the features of chemical element distribution in cast iron phases, dislocation density in a solid solution, crystal lattice parameters, and others were studied. Findings. It has been shown that solid-phase auto-epitaxy is a physically justified, experimentally proved and stably reproducible phenomenon. The accelerated transfer of carbon atoms to the surfaces of metastable diamond growing crystals in the kinetic mode is facilitated by a number of factors that cannot be quantified by numerically evaluated parameters. These include, first of all, the microstructure of the growing medium (cast iron matrix), carbon source, temperature and deformation fields that ensure transformation of polymorphic graphite to diamond with emerging gradient stress fields at the stages of forging, exposure to shock waves and thermal cycling. Defect redistribution in the crystal structure of the metal matrix and graphite inclusions plays a certain role at the mesoscale. It has been found that saturation with microstructural defects brings higher physicochemical activity to the system in the whole. Originality. For the first time in world practice, diamond single crystals have been synthesized that contain the inclusions of polycrystalline diamond particles of shock-wave origin inside the single crystal shell; this may indicate a general discreteness of natural diamond formation. Practical value. The growth of single metastable crystal on polycrystalline diamond of shock wave synthesis is the most favorable in case of using austenitic gray cast iron with foliate graphite inclusions. The experimentally proved diamond growth in a solid medium under pressure and temperature within the range of graphite stability can be used to develop new low-energy technologies for the synthesis of metastable diamond single crystals. | ||
| 13. | 
Baskevych O. S. Modeling the influence of shock waves on the stability of chemical links during super-deep penetration of microparticles [Електронний ресурс] / O. S. Baskevych, V. V. Sobolev, B. P. Sereda // Математичне моделювання. - 2020. - № 1. - С. 116-124. - Режим доступу: http://nbuv.gov.ua/UJRN/Mm_2020_1_17 | ||
| 14. | 
Ishchuk V. M. Solid solutions with coexisting ferroelectric and antiferroelectric phases for creation of new materials [Електронний ресурс] / V. M. Ishchuk, V. L. Sobolev // Фізика низьких температур. - 2020. - Т. 46, Вип. 8. - С. 959-962. - Режим доступу: http://nbuv.gov.ua/UJRN/PhNT_2020_46_8_15 Контрольований процес розпаду твердих розчинів поблизу міжфазних меж, що розділяють домени співіснуючих антиферо- та фероелектричних фаз, відкриває нові області застосування для цих матеріалів. Тверді розчини на основі цирконата-титаната свинцю розглянуто як приклад речовин, придатних для створення матеріалів із від'ємним показником заломлення. Виготовлені композити є діелектричною антифероелектричною матрицею зі структурою провідних міжфазних меж, що розділяють домени феро- та антифероелектричної фаз. Електропровідність міжфазних меж виникає внаслідок локального розпаду твердих розчинів поблизу цих меж. За допомогою зовнішніх впливів можливо контролювати процес розпаду і, таким чином, провідність міжфазних меж. | ||
| 15. |
Baskevich O. Modeling of conditions of phase transformations in micro-areas of metal materials with extreme penetration of microparticles [Електронний ресурс] / O. Baskevich, V. Sobolev, B. Sereda, D. Sereda // Математичне моделювання. - 2021. - № 2. - С. 91-102. - Режим доступу: http://nbuv.gov.ua/UJRN/Mm_2021_2_13 | ||
| 16. |
Sobolev V. V. On the mechanism of ionization of atoms at compression of a substance by front of the converging shock wave [Електронний ресурс] / V. V. Sobolev, S. M. Hapieiev, O. V. Skobenko, V. V. Kulivar, A. V. Kurliak // Naukovyi visnyk Natsionalnoho Hirnychoho Universytetu. - 2022. - № 3. - С. 57-66. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2022_3_11 Purpose. To study changes in the microstructure of metals after exposure to high-energy plasma jets formed by the cumulation of gas-dynamic flows in a conical target. To estimate the expected state of matter in a strong shock wave compression, taking into account the change in volumetric energy density at the moment of transformation of a solid body plasma into nuclear matter. Methodology. The technique of laser initiation of a profiled front of detonation waves in explosive charges and the corresponding profile of shock waves in materials, methods and techniques for measuring the dynamic parameters of shock-compressed substances are used. Findings. An experimental study on the physicochemical state of a substance that has been processed with extremely high pressures and temperatures during compression by converging shock waves in conical targets has been carried out. Scientific results of physical and mathematical modelling of converging shock waves are analysed. Originality. For the first time, the formation of symmetric plasma jets during gas compression in conical targets has been experimentally observed. For the first time, metallo-physical studies on the microstructure of cast iron and steel have been carried out. These studies were made after the action of high-energy dense plasma jets with a temperature of (2,5 - 2,8) x 10<^>6 | ||
| 17. |
Sobolev V. V. Formation of converging cylindrical detonation front [Електронний ресурс] / V. V. Sobolev, O. V. Skobenko, I. I. Usyk, V. V. Kulivar, A. V. Kurliak // Naukovyi visnyk Natsionalnoho Hirnychoho Universytetu. - 2021. - № 6. - С. 49-56. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2021_6_10 Purpose. To develop a laser method for initiating a converging cylindrical front of a detonation wave and a method for calculating the kinematic parameters of the cylindrical shell walls, accelerated by the pressure of the detonation products of an external explosive charge. Methodology. An experimental technology for the manufacture of a photosensitive explosive composite and an experimental technique for igniting the surface of its layer with an extended laser beam without the use of a fiber-optic cable are used. The results of simulation modeling - the Monte Carlo method - were used to study the effect of illumination on the process of ignition of explosives by laser pulsed radiation. For the selected type of photosensitive explosive composite, its explosive and optical characteristics, the distance from the surface of the explosive charge to the lens scattering the laser beam, and taking into account the total area of the expanded beam, the regularities of the distribution of the radiation energy density over the vertical and horizontal sections of the laser beam were studied. Findings. The analysis of the scientific and technical level of methods of shock-wave processing of materials in the region of ultrahigh pressures from the point of view of the fundamental value of the cumulation of energy in the waves of a converging cylindrical detonation and shock front is carried out. Physicomathematical modeling was carried out and the regularities of pressure increase in the wave front were established in the process of approaching the shell walls to the axis. The scientific results of modeling converging cylindrical shells under the influence of the pressure of the explosion products have been analyzed. A method for laser initiation of a converging cylindrical front of a detonation wave has been developed, and a method for calculating the kinematic parameters of the converging walls of a cylindrical shell has been proposed. Originality. A technique has been developed for determining the energy characteristics of an expanded laser beam, calculating the laser radiation energy required to initiate detonation simultaneously on the entire lateral cylindrical surface of a photosensitive explosive composite. The idea of technical implementation of the cumulation of converging cylindrical detonation and shock waves was developed further. A technique has been developed for the numerical determination of the change in the internal average compression rate of the shell during the movement of its walls towards the axis for various ratios of its external radius to the wall thickness and taking into account the increase in pressure in the converging detonation front. Practical value. For the first time, a method for laser initiation of a converging cylindrical front of a detonation wave was developed and a device was tested that forms a converging cylindrical front of a detonation wave and a corresponding shock front in the material under study by the impact of a metal shell converging to the axis. The core of the device is a laser explosive initiation system that uses light-sensitive explosive composites to initiate an explosive charge. | ||
| 18. |
Burchak O. V. Impact of weak electromagnetic fields on the properties of coal substance [Електронний ресурс] / O. V. Burchak, V. V. Sobolev, K. A. Bezruchko, O. S. Kovrov, A. V. Kurliak, K. Jach // Naukovyi visnyk Natsionalnoho Hirnychoho Universytetu. - 2022. - № 5. - С. 46-53. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2022_5_9 Purpose. To establish the regularities of the influence of magnetic fields on the peculiarities of changing the chemical and structural characteristics of the coal substance according to the size of microparticles enriched with vitrinite. To formulate a new system of views on the mechanisms of structural and functional transformations of coal substance under the influence of weak external fields. Methodology. The authors used an electric furnace heating up to 320 K that creates a pulsation magnetic field with a strength of up to 4,000 A/m to process dispersed samples of hard coal with a weak magnetic field. The methods of infrared spectroscopy and electron paramagnetic resonance were used in the research. Findings. Experimental works were carried out to estimate the impact of weak fields on the state and properties of coal substance. It is shown that weak energy fields, and the electromagnetic one in particular, are able to reduce the energy barriers of reactions in coal substance due to spin-spin interaction, which leads to the activation of processes at the atomic-molecular level and interfacial interaction. Originality. It is experimentally established that for coal micro-particles with sizes from 0,16 to 0,1 <$E mu>m, enriched with vitrinite, the coupling coefficient decreases after exposure to an external magnetic field, and for micro-particles with sizes less than 0,63 <$E mu>m, this indicator increases. Such changes are caused by the redistribution of hydrogen between aromatic and aliphatic components during free-radical reactions. Changes in the spectrum on vitrinite (0,16 - 0,10 mm), are more significant than on inertinite (0,063 - << 0,05 mm). At the same time, the external action of the electromagnetic field has caused the opposite consequences. It is shown that magnetically stimulated chemical reactions occurring in the coal substance are aimed at the recombination of free radicals with active surface states of the organic mass of coal into stable gas molecules. The results of laboratory studies using the methods of electron magnetic resonance and infrared spectroscopy and infrared spectroscopy allow assuming that the changes in structural characteristics recorded during experiments with low-energy impacts can be considered as intermediators for the matter transformation or changes in the state of coal in preparation for structural and functional transformations. For example, to the sorption interaction or destructive processes with methane generation. Practical values. The magnetic field effect can be used to develop new research methods for the study on elementary processes by electron spin resonance; control spin-dependent phase transitions. The use of magnetic resonance methods allows the usage of magnetically field effects in the form of basic tools for the research on structural defects. The results obtained will be a scientific ground for the development of methods for estimating the parameters of electromagnetic processes in coal to develop new technologies for the extraction and processing of hydrocarbon energy carriers. | ||
| 19. |
Sobolev V. V. Magnetic stimulation of chemical reactions in coal [Електронний ресурс] / V. V. Sobolev, N. V. Holub, O. A. Tereshkova // Naukovyi visnyk Natsionalnoho Hirnychoho Universytetu. - 2023. - № 4. - С. 48-55. | ||
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