Home – Home – Jornals – Journal of Mining Sciences 2016 number 2

A model of single filamentation of a high-power ultrashort light pulse has been developed on the basis of evolutionary dependences of phase and amplitude parameters of the light field derived from numerical solution of the nonlinear Schrödinger equation for air. A key role of aberrations and diffraction effects during formation of stable dynamic light structures near the propagation axis is shown. It is found that the angular divergence of post-filamentation light channel decreases with increasing radius of the laser beam at a fixed pulse peak power and reaches saturation at the radius greater than 1 mm.

Based on the numerical solution of the parabolic wave equation for the complex spectral amplitude of the wave field by using the splitting into physical factors method the fluctuations of energy density of the broadband pulsed optical radiation for various modes of Laguerre-Gaussian beam under different turbulent conditions on the propagation path were studied. It has been shown that with the increase of optical turbulence the relative variance of energy density fluctuations of pulsed radiation of femtosecond duration becomes much lower than that of continuous-wave radiation and, in contrast, may become smaller than unity. Provided the pulse duration is short the energy density fluctuations tend to decrease as the order of Laguerre-Gaussian beam mode rises. The level of residual spatial correlation of strong energy density fluctuations of pulsed radiation exceeds the level of continuous-wave intensity correlation in all examined Laguerre-Gaussian beam modes and the typical two-scale structure of spatial correlation for strong fluctuations of continuous-wave radiation in the case of pulsed radiation is less expressed.

Normalized temporal autocorrelation function of fluctuations of the scattered radiation of a focused laser beam (0.63 μm) in the surface atmosphere in precipitation (rain, drizzle), fog, and haze on a path with a length of 130 m is measured. It is found that the time correlation of the fluctuations of the scattered radiation of a focused laser beam in the rain, drizzle, fog, and haze decreases with increasing wind speed component noramal to the path at close atmospheric conditions (at close values of optical depth and particle size). The correlation time in drizzle is more than in the rain. The correlation time in haze is more than in the rain and drizzle. The correlation time in the fog is an order of magnitude or even more longer than in the rain.

Transformation of C₂H₄, CO₂ and C₂H₆ absorption spectra under condition of nanoconfinement in SiO₂/Al₂O₃ aerogel is presented for the first time. It is shown that integral intensity of confined C₂H₄ within 5700-6250 cm^-1, CO₂ within 4760-5160 cm^-1 and C₂H₆ within 2830-3030 cm^-1 are respectively by 13.3, 15, and 18 times higher than in free gas.

The description of published data on properties of spectral line parameters for deutero-substituted isotopologues of hydrogen sulfide molecule (HDS, HD³⁴S, D₂S и D₂³⁴S) is given. The majority of the properties characterize the results of vacuum wavenumber quality analysis. Two applications used for data quality analysis in information system W@DIS are described. The results of computed data quality analysis of vacuum wavenumbers are completed by the expert assessment of quality of the same set of data. The data sources containing parameters of vibration-rotational transitions and energy levels deutero-substituted isotopologues of hydrogen sulphide molecule acquired from publications are stored in databases of information system W@DIS and provided the formal description of their properties. The properties and their values are represented in ontological knowledge base and accessed in W@DIS (http://wadis.saga.iao.ru/) via Internet.

Three algorithms of the Monte Carlo method for calculation of impulse transfer function in channels of laser sensing and communication are considered: the local estimation algorithm, the double local estimation algorithm, and the suggested modified double local estimation algorithm. Results of testing of the algorithms and their comparison are considered. For a homogeneous medium, the complexities of the algorithms are compared, demonstrating under what conditions the suggested algorithm is advantageous as compared to the double local estimation algorithm. The contributions of double, triple, and higher-order scattering are numerically estimated. High contribution of multiple scattering proves the expediency of application of the Monte Carlo method for solving problems of this type.

We have proposed a method for solving the inverse problem of multifrequency lidar sensing of the atmospheric aerosol, which enables to retrieve the spatial distribution of volume concentrations of aerosol components, aerosol particle size distribution integrated along the sensing path, and the complex refractive index of the particles, without any additional data for calibration of the lidar and for supplementary definition of the inverse problem. The method is based on the assumption that the average sizes, the variance of sizes and the complex refractive index of the particles of each aerosol components do not change along the sensing path, and the number of lidar spectral channels is greater than the number of aerosol components. In this case the system of equations for the spectral-temporal readings of lidar signal becomes overdetermined, and its numerical solution allows determining not only the microphysical parameters of aerosol but also lidar calibration constants at operating wavelengths. Examples of processing of elastic and Raman scattering lidar signals of model aerodispersive medium at wavelengths λ₀ = 0.355, 0.532, 1.064 μm and λ_R = 0.387, 0.607 μm, respectively, were presented. It is shown that microphysical parameters of fine components (with particles size less than 1-2 μm) are retrieved from the signals with an error less than 10%. The error of microphysical parameters of coarse particles retrieval is strongly dependent on the significance of their contribution to the total transmission of the medium. The difference between aerosol extinction and backscatter coefficients calculated on the base of retrieved microphysical aerosol parameters and their actual values are within a few percents.

Monitoring of the state of vegetation of oil producing areas of Western Siberia for the period 2010-2015 using thematic products MODIS are carried out. The approach is suggested to assessment of the impact of various factors on the environment areas of oil and gas on the base of remote sensing data by NDVI. Testing of the approach undertaken for the technologically-disturbed areas of four oil fields in Tomsk region - Krapivinsky, Ladyzhensky, Luginetskoye, and Urmanskoye. Additionally, as the background area, the area of ​​the State nature reserve of regional importance “Oglatsky” is studied.

Twelve air temperature and humidity measurement series were carried out with the use of AKV-2 mobile station in Tomsk and its suburbs in different seasons and under different weather conditions. The urban heat island effect is shown to be observed in Tomsk in all seasons; the mean temperature increment is 2 °C in winter and 1 °C in summer. The fields of absolute humidity differ significantly for warm and cold seasons in Tomsk. It is shown that the humidity in Tomsk is mainly of anthropogenic origin in winter and of natural origin in summer.

The relative contribution of different factors into formation of the urban heat island in Tomsk is estimated. It is shown that the key factors are anthropogenic heat emissions (80-90% in winter and 40-50% in summer) and absorption of short-wavelength radiation by the urban underlying surface (5-15% in winter and 40-50% in summer), while the absorption of long-wavelength radiation by the underlying surface, absorption by moisture and admixtures, and heat loss on the evaporation contribute insignificantly. It is shown that the turbulent heat flow prevents a linear increase in the intensity of the urban heat island with an increase in the sum of radiation fluxes that ensure the energy income into the heat island region. Due to an increase in the turbulent heat flow in Tomsk, 40-50% of the absorbed energy is carried over in summer and 20-30% in winter. An equation is suggested that allows calculation of the heat island intensity in different seasons, time, and under different atmospheric conditions from weather parameters measured at a stationary site.

A narrowband VUV radiation (near a wavelength of 147 nm) corresponding to optical transitions of the heteronuclear dimer ArXe from plasma formed during the excitation of the Ar-Xe mixture at a pressure of 400 mbar with high-voltage nanosecond discharge initiated by runaway electrons was registered. Amplifying properties of the discharge plasma with respect to this radiation were found.

Particular properties of formation of the optical field in the composite spherical microcapsules of different size consisting of a polymer absorbing shell and a non-absorbing liquid core are presented. The numerical simulation shows that changes in the thickness of the shell, grown on the core fixed radius, and the coefficient of its own radiation absorption determine the nature of spatial distribution and amplitude characteristics of the absorbed power. Variations in these parameters allow changing position and peak values of the areas of the effective absorption volume of the particle and, consequently, create conditions favourable for opening the shells in the appropriate spatial areas. This is important for the solution of practical tasks associated with the problem of release of the contents of the microcapsules.

The calculations results of LED light intensity necessary for reliable visual detection of runway lights in field conditions are presented. The following groups of LED lights are considered: approach threshold lights, lights of the last 600 m of a runway, and runway end lights. Detection threshold were chosen. The effectiveness of LED lights is analyzed in different weather conditions during the night, at twilight, and in the day time, and questions of speed adjustment of LED radiation intensities in accordance with ICAO standards are considered.

The article focuses on efficient analysis and test methods to determine nano- and micro- physico-mechanical properties of rocks and crystals. A modification of the classical elastic problems of contact mechanics implemented using the mathematical apparatus of fractional integro-differentiation is proposed. The authors build new models and algorithms aimed to advance the studies into properties and states of geomaterials based on the atomic-force microscopy techniques, and describe testing of the new approaches in calculation of the elastic modulus for hydrocarbons with nano-additives.

The analytical review covers the key factors that influence permeability of a coalbed under mining-induced alteration of stress state. The authors put forward an analytical relation between coal permeability, stresses and adsorbed gas to define parameters of gas leakage zone parameters and laws of mass-transfer. The analytically derived relation is compared with the known model of coal structure and with the experimental results. The proposed model of coalbed permeability allows mechanism of leakage and localization of seepage zones in coal provided that the model parameters are properly selected or found experimentally.

The article offers in situ test methods for cohesion and internal friction angle in rocks and at joints. Technologies and instrumentation for shearing of rock wedges in an open pit mine and for laser scanning and digital imaging of local falls and breaks of inaccessible rock blocks in pitwalls have been developed and approved for constructing of a limit equilibrium equation and for calculation of strength properties of rocks and joints. Rock wedges for the tests are prepared using various design drill rigs, the rock wedges are sheared using a 40-t jack placed in a special metal housing with an electric hydraulic pump. Exploration of inaccessible local falls in pitwalls uses electronic tachometers and 3D mine scanner. The tests and approval of the described exploration techniques have been carried out in open pits in Kazakhstan and Kirgizia.

The scope of the article encompasses features of natural and induced seismicity and the change in frequency plots when natural seismicity becomes natural-and-induced seismicity in mining areas and when induced seismicity becomes natural-and-induced seismicity in mines. It is shown how induced seismicity is connected with the subsidence of overlying strata in mines-seismic process propagates together with the subsidence but seismic activity lowers in the time of maximum subsidence and intensifies when subsidence ceases or decelerates. The authors lay emphasis on estimates of seismic activity in mines and give details of an integrated index F procedure tested in mines and adjusted within the 10 year-long period of application.

The solution to a hydraulic fracture problem for the model of Khristianovich-Geertsma-de Klerk is obtained on the basis of the modified formulation of the problem, which, in contrast with the conventional approach, employs the particle velocity rather than the flux. This served to complement the system of ordinary differential equations, resulting after spatial discretization, with the speed equation. The complete system is solved by the Runge-Kutta method for arbitrary initial conditions.The decaying influence of the initial conditions on key characteristics of a fracture (opening and length) at the end of a treatment is established and numerically analyzed.

Based on the strength and crack resistance tests of dolerite and gabbro-diorite samples subjected to bending as a function of loading rate, it is shown that the kinetic constants of strength in Zhurkov model have the same values in the localized and nonlocalized failure modes. The tests on destruction of an organic glass sample with an edge crack yield the similar results.

The article gives the results of mathematical calculations of change in the parameters of electromagnetic signals in stratified and damaged dielectric solid model structures exposed to pulsed acoustic treatment. It is shown that the acousto-electric transformations in such structures result in transition of energy of acoustic pulses to energy of electromagnetic responses in double electric layers. The amplitude-frequency parameters of electromagnetic signals are directly connected with the characteristics of the determinate acoustic effects and with the charge state of the stratified and damaged structures.

Perovskite-like compounds with the general formula La_{1 - x} Bi _x Mn_{1 - y} M _y O_{3 + } (M = Fe, Ni, Cu; x = 0.1-0.3; у = 0.0-0.2,  х =  у = 0.1) were obtained by solid-phase synthesis and characterized by means of XPA, TG and dilatometry. For solid solutions with rhombohedral structure, the existence of two regions in the linear dependence of unit cell volume on temperature was explained by thermal expansion of samples.

Results of the synthesis of multilevel nanometre-sized cermets with interpenetrative structure based on -Bi₂O₃/Ag, for selective medium-temperature oxygen membranes needed for novel clean coal-based power engineering are presented. In particular, the size of crystallites of the components was decreased to 10-20 nm; the composition of the ceramics was improved by adding Pr; silver is doped heterogeneously by fluorite, with the conservation of compatibility and with increased fraction of silver in cermet with interpenetrative structure; nanocermets are modified with Pd. In spite of the significant improvement of the composite characteristics in comparison with known cermet 60Bi_0.75Er_0.25O_1.5/40Ag, the problem of making a real material for membranes has not been solved. Membrane degradation in all positions at T ~ 600 °C comes to the forefront. Along with optimization of the composition and method to obtain membrane material, it is proposed to decrease the working temperature to T ~ 500 °C.

Aluminium oxide systems were studied using a set of X-ray diffraction methods: Rietveld method, modelling of diffraction patterns of one-dimensionally disordered materials, modelling of fine dispersed substances, method of the radial distribution of electron density. Modelling of diffraction patterns of aluminium hydroxide and the curves of the radial distribution of electron density of oxides and hydroxides was carried out. Using the data of previous modelling, the real structure of aluminium hydroxides with different physicochemical properties and oxides obtained from them was studied. The results may be used in the analysis of any real object containing aluminium oxide systems, first of all nanometre-sized ones.

Nanopowders of α-Al₂O₃ were synthesized through crystallization of aluminium hydroxide gel with nanoparticles introduced into it as seedings. Depending on the gel crystallization conditions, the powder consists either of weakly aggregated spherical particles or of polygons with irregular shapes. It was established that particle shape is determined by the composition of the gas phase during crystallization, in particular by water vapour pressure. The temperature at which the gel is completely crystallized into the α-phase depends on the content of micro-impurities in the solution from which the gel is formed. Under optimal synthesis conditions, α-Al₂O₃ nanopowders with particle size about 100 nm are reproducibly obtained. The powders exhibit good moldability and sintering ability to form almost pore-free ceramics at 1300 ^oC.

Comparative analysis of two methods EXAFS and PDF to study the phase composition and local structure (interatomic distances and coordination numbers) of materials including nanomaterials was carried out. The shortcomings and advantages of the methods are considered.

Effect of mechanical activation (MA) of hexagonal boron nitride ( h BN) powder with different intensities in attritor and in a planetary ball mill (PBM) on the structure and phase composition of materials based on this compound was studied. Mechanical activation of h BN powder was carried out in order to decrease the parameters of synthesis of cubic boron nitride ( c BN) due to the formation of nanostructure in h BN. The stoichiometry of h BN is observed to decrease during MA due to partial decomposition. Mechanical treatment of h BN powders in PBM proceeds more intensively and leads to the formation of particles with crystallite size 5-10 times smaller than the size of crystallites formed during treatment in attritor. The specific surface increases by a factor of 3-6. After agglomeration of powders after MA at a pressure above 7 GPa, the phase composition of the resulting material is independent of the intensity of MA and is characterized by the presence of the cubic phase of BN alone.

Results of chemisorption measurements and experiments on hydrogen thermodesorption carried out with Pt/γ-Al₂O₃ samples with Pt nanoclusters (size <1 nm) are presented. The reasons of the reversible changes of adsorption properties were studied. The results are compared with the data for platinum nanoparticles (with the size mainly 2-3 nm) deposited on the “inert” oxide (SiO₂). The high sensitivity of chemisorption methods and temperature-programmable desorption to the changes in the state of supported metal clusters during thermal treatment of the samples in reducing and neutral media was demonstrated. It was shown that hydrogen adsorption on ultrafine systems is activated, and the adsorption capacity of samples determined from oxygen-hydrogen titration may decrease during multiple titration procedures. A strong effect of Н₂О on hydrogen thermodesorption from Pt/γ-Al₂O₃ samples reduced at high temperature was observed. The obtained results are interpreted taking into account the structural changes of nanoclusters in the low-temperature region and the formation of oxygen vacancies at the metal - support interface under the action of H₂ at high temperature.

Intra-mold modification of 110G13L steel was carried out using various dispersed modifying agents containing boron, tungsten, titanium carbides, ferrotitanium, and carbon as the active phase. To improve wettability, modifying agents were treated preliminarily with copper powder in AGO-3 planetary centrifugal mill. It was discovered that the microstructure of the formed steel samples is composed of austenite and carbides released inside the grains and along their boundaries. A significant increase in the point of maximal load by 14.5, 18.0 and 9.0 % was demonstrated by the steel samples treated with the modifying agents containing boron carbide (concentration of the active phase: 0.056 %), a mixture of tungsten and titanium carbides (0.033 %) and titanium carbide (0.083 %), respectively. In addition, the use of a mixture of tungsten and titanium carbides allowed us to increase relative elongation by 40 %. The use of the modifying agents containing boron carbide and a mixture of tungsten and titanium carbides promotes uniform distribution of carbides and a substantial decrease in grain size; the grain size (according to the State Standard GOST 5639) corresponds to two points (the actual grain diameter is 0.387-0.694 and 0.338-0.581 mm, respectively). The grain size in the reference sample is more than three points (the actual grain diameter is 2.325-3.168 mm). The grain size in other modified steel samples corresponds to three points and more.

Structural-chemical changes in high-silica zeolite-containing rocks from the Kholinskoye and Shivyrtuy deposits (Russia) under the action of mechanical activation in a laboratory vibrogrinder were studied by means of differential scanning calorimetry, thermogravimetry, densimetry, air permeability measurement, atomic emission spectroscopy with inductively coupled plasma, infrared spectroscopy, X-ray phase analysis. The kinetic parameters of dehydration of initial and mechanically activated natural zeolites were calculated (apparent activation energy, pre-exponential factor), as well as their thermodynamic potentials (enthalpy of formation, entropy and Gibbs energy), and disordering degree. The degree of carbonization of the samples under study was estimated with the help of the analysis of infrared spectra and thermogravigrams. It was demonstrated that the change of the reactivity of natural zeolites as a result of mechanochemical treatment is determined by the phase composition off initial samples.

Nickel boride Ni₃B is a promising material for making self-regulated heating elements. In the present work, the synthesis of nickel boride Ni₃B and its compaction were carried out for the first time by means of electric spark agglomeration. Two approaches were considered for obtaining sintered materials based on Ni₃B: 1) reactive electric spark agglomeration of the mixture of 3Ni + B subjected to preliminary mechanical treatment; 2) obtaining Ni₃B by means of thermal explosion in mechanically treated powder mixture, followed by compaction of the resulting product with the help of electric spark agglomeration. It was established that the material based on Ni₃B, obtained by reactive agglomeration, is characterized by lower content of admixture phase Ni₂B and higher relative density and microhardness in comparison with the material obtained by sintering the product of thermal explosion at the same temperature. Specific electric conductance of agglomerated materials based on Ni₃B is about 10^-3 Ohm x cm.

The samples of MoS₂ with added small amounts of polar liquids were synthesized for the first time by means of soli-phase mechanical activation of commercial molybdenite. Physicochemical characteristics of the catalysts are discussed that have been measured by means of sedimentation analysis, XSA, XPES, TEM, thermal analysis. The high activity of the catalyst with small added amount of methanol was discovered in the model reaction of dibenzothiophene hydrogenolysis. It is demonstrated that the level of detect content does not determine the hydrodesulphurising ability of monocatalysts in the model reaction. Interconnection between the physicochemical characteristics of the catalysts and their activity in the model reaction was studied. Conclusions concerning the reaction routes were made on the basis of analysis of the composition of hydrodesulphurising agents by means of gas chromatography-mass spectrometry.

The interaction of solid bismuth oxohydroxonitrates having the composition [Bi₆O₄(OH)₄](NO₃)₆ x 4H₂O (I), [Bi₆O₅(OH₃)](NO₃)₅ x 3H₂O (II) and [Bi₆O₄(OH)₄](NO₃)₆ x H₂O (III) with the aqueous solutions of citric acid was studied by means of X-ray phase analysis, electron microscopy and atomic emission spectroscopy. The conditions for the formation of bismuth citrate having the composition BiC₆H₅O₇ were determined.

Mechanochemical synthesis of anhydrous sodium thiosulphate Na₂S₂O₃ was carried out for the first time by means of mechanical activation of the stoichiometric powder mixture of sodium sulphate (Na₂SO₃) and sulphur (S) in the ball planetary mill “Aktivator-2SL”. By means of iodometric titration, X-ray phase analysis and thermal analysis, it was established that under relatively mild conditions of mechanical activation for about 1 h the degree of transformation in the solid-phase reaction Na₂SO₃ + S = Na₂S₂O₃ reaches 95 %.

For steel and copper as example, the processes of structure formation are considered, taking place under the conditions of intense plastic deformation which is initiated by different kinds of dynamic loading in the zone of contact between the metals of different kinds. It is shown that intense plastic deformation promotes an increase in mutual solubility metals in each other and the formation of atomically ordered phases. In the case of ultrahigh pressure, the formation of atomically ordered phases was not detected. This is connected with the fact that the free atomic volume in the liquid phase, formed in the cumulative jet, exceeds the free volume during solid-phase interaction. A set of the models of structure formation under the gradient conditions can be united within the framework of the scheme “shear-turn”.

Effect of the nature of decomposition of the particles of cobalt azide deposited in the pores of carbon matrix on the phase composition and particle size characteristics of the products is considered. Porous carbon material of Sibunit type, of TU-145 grade (pore diameter 10-15 nm) was used as the matrix. The studies were carried out by means of X-ray diffraction, X-ray fluorescence analysis, complexometry, and thermogravimetry. It was established that mainly the Co₃O₄ phase is formed as a result of the slow decomposition of cobalt azide nanoparticles, while the product of explosive decomposition contains the metal phase and CoO.

Dependencies of the critical energy density of the initiation of explosive decomposition of PETN-Co nanocomposite on nanoparticle radius and the duration of the pulse of the first harmonics of neodymium laser were calculated using the microfocal model of thermal explosion. For each pulse duration, the minimal values of the critical energy density for the initiation and the corresponding radii of nanoparticles were determined. The calculation was carried out in two versions: 1) with the coefficient of absorption efficiency equal to 1, which is independent of nanoparticle radius; 2) taking into account the dependence of absorption efficiency coefficient on the radius of cobalt nanoparticle in a transparent matrix with the refractive index equal to 1.54 (PETN), calculated within the framework of Mie theory. For pulse duration shorter than 100 ns, calculation results differ substantially: neglect of the regularities of absorption by cobalt nanoparticles leads to a decrease in the minimal energy density by a factor of more than 17 for pulse duration 0.1 ns, while taking into account the dependence of the coefficient of absorption efficiency on particle radius, the energy threshold in this range decreases only by a factor of 3. The account of the dependence of laser pulse absorption efficiency coefficient on nanoparticle radius allows solving the paradox of small particles.

Products of the interaction of diphenolic compounds (diph) hydroquinone, resorcinol, pyrocatechin with silicon oxide with the formation of chains of the general formula diph-(Si(OH)₂-diph) _n were studied by means of computer modeling. For each compound, inertia radius and other spatial characteristics were calculated; the fractal dimensionality was determined within the row of compounds. It was concluded on the basis of the results that for the compounds of hydroquinone and resorcinol series the shape of the polymer chain is a rod, while for the pyrocatechin series its shape is a stochastic clew.

Supramolecular structure of arabinogalactan and its complexes with betulin diacetate was studied. Using the methods of small-angle X-ray scattering and laser ablation, the presence of arabinogalactan associates in solution was demonstrated. The formation of these associates may proceed due to the interaction either with water molecules or with betulin diacetate molecules.

Effect of mechanical activation of brown and oxidized coal in the presence of alkaline reagent and abrasive material in different concentrations was demonstrated. Solid-phase mechanochemical reactions of humic acids with the salts of heavy metals were carried out. The features of structural transformations of humic acids during mechanical activation were revealed.

Effect of the conditions of mechanochemical activation on the efficiency of enzymatic hydrolysis of carbohydrates incorporated into highly lignified plant raw material - reed stem biomass was studied. Complicated supramolecular structure and high lignin content in the structure have a negative effect on enzymatic hydrolysis. The model conditions of fragile grinding and plastic deformation of the material under different temperature of mechanical activation are considered. The samples obtained by mechanical activation of lignocellulose material are characterized by increased reactivity in enzymatic hydrolysis due to an increase in the surface area and disordering of the crystalline regions in cellulose. Optimal conditions for mechanical activation of plant raw material for obtaining highly reactive products were established.