The content of organic carbon is one of the key indicators in determining the areas of using waste of mining, processing and combustion of coal. The measurement results obtained by existing measurement methods are often incomparable to each other, which does not allow obtaining a reliable information about the waste composition. The goal of this study is to generalize current methodological approaches and choose the most effective one for determining the content of organic carbon in samples of waste of mining, processing and combustion of coal. Three most appropriate methods were selected proceeding from the analysis of the methods used for determining organic carbon in various natural and technogenic objects. Method No. 1 is based on the calculation of organic carbon content as the difference between total carbon measured by a CHN analyzer and carbonate carbon determined by the gravimetric method. In method No. 2, the determination of organic carbon content is carried out through the determination of the ash, moisture and carbonate carbon content. Method No. 3 includes demineralization of the sample with hydrochloric acid, drying, and calcination of the resulting residue. The samples of waste of mining, processing and combustion of coal with mass fraction of organic carbon from 0 to 60% were used as objects of the research. According to the results of experimental studies and taking into account possible limitations, measurement procedure based on method No. 3 for determining the content of unburned carbon in ash and slag from a thermal power plant was chosen. The applicability of the newly developed measurement procedure was verified for an extended area of objects, which includes, in addition to the samples of coal combustion waste, the samples of waste of their mining and processing. The comparability of the results obtained by other methods was demonstrated, and a preliminary assessment of the metrological characteristics was performed. The measurement procedure can be used in analysis of the reference samples used for construction of the calibration characteristics in the determination of organic carbon by instrumental methods, as well as in the determination of the metrological characteristics of the reference materials of the composition of waste of mining, processing and combustion of coal.

An approach to the determination of the composition of novel biocompatible materials based on cerium-containing calcium phosphates by TXRF is proposed. The ranges of analyte contents in solutions for the correct determination of Ca, P, Ce by the external standard method were determined. A systematic underestimation of the calcium signal at a Ca content in the analyzed composite sample above 30 mg/liter is noted. The Compton scattering spectra for the ceramic sample solution were analyzed to assess the compliance of the sample with the thin layer criterion, the maximum value was 16. 8 keV (96°). According to the graph of the mass attenuation coefficient for a film of a given composition, the attenuation of the calcium line is not related with the absorption effect of the sample. The internal standards (Gd and Cu) were selected and conditions for the determination of micro- and macro-components in solutions and suspensions of samples were determined. It is shown that with a calcium content up to 50 mg/liter in the sample, it is possible to determine correctly Ca, P, and Ce by TXRF method in solutions and suspensions with S_r 0.05 and 0.09, respectively. The convergence of the results obtained is noted by the methods of external and internal standards with appropriate dilutions of solutions and suspensions.

The content of selenium and tellurium used in steels and alloys as alloying additives is strictly regulated by the current state standards. The methods of analysis used in state standards are often lengthy and laborious and do not provide their simultaneous determination. Development of alternative methods for the determination of selenium and tellurium in metallurgical materials using modern analytical equipment is an urgent goal. The method of atomic emission spectrometry with inductively coupled plasma (ICP-AES) is widely used in analysis of metallurgical materials. However, the components of the sample base can significantly affect the results of ICP-AES analysis. We present the results of theoretical and experimental study of the effect of the components of the base of samples of metallurgical materials (iron, nickel, chromium, molybdenum, cobalt, copper, tungsten) on the spectral analytical lines of selenium and tellurium. Thermodynamic modeling was used for theoretical prediction of the processes occurring during atomization of the analyzed solutions in argon plasma. It is shown that matrix non-spectral noise on the selenium line is attributed to chromium (at chromium concentrations above 50 mg/dm³), whereas the matrix non-spectral noise on the tellurium line is not observed. It is also shown experimentally that the spectral lines of selenium and tellurium are not free from spectral overlaps attributed to macrocomponents (iron, nickel, chromium, molybdenum, cobalt, copper and tungsten). To reduce the limits of detection and improve the reliability of ICP-AES determination of selenium and tellurium, it is necessary to separate them from the components of the sample base.

Many technological processes occurred upon the extraction and primary processing of coal (dust suppression, grouting, hydraulic fracturing, wet enrichment, etc.) depend on the wettability of the coal surface, determined by the physicochemical properties of the interacting media. The filtration properties of a fractured-porous coal massif significantly depend on the wettability of the surface. We present the results of studying the wettability of the coal surface with water and its filtration through a layer of coal powder. It is shown that the increased humidity of coal contributes to an increase in the wetting and filtration properties of the coal layer in relation to water due to the creation of a hydrate shell at the contact surface. It is revealed that the method of coal sample preparation significantly affects the functional composition and hydrophilicity of the outer surface of coal particles. Grinding coal in the presence of oxygen in air contributes to the formation of polar oxygen groups (hydroxyl, carboxyl) on the surface of coal particles, which leads to an increase in the hydrophilicity and filtration properties of coal. The results obtained can be used to predict the wettability of coals with process fluids, to improve technologies for mining, enrichment and processing of coals.

Thin-film coatings for optical elements are widely used in various industries. Antireflection coatings are used in display screens, photodetectors, fiber optic light guides, mirror coatings are used for telescopes, medical equipment, etc. One of the main goals in the production of thin-film coatings is to determine the refractive index and the choice of materials applied to optical products. We present the results of determining the refractive indices of materials used for the manufacture of multilayer mirrors with the desired spectral characteristics. In general, light reflection occurs at the interface between two materials, for example, glass and air. Dielectric films were obtained by high-frequency ion-beam sputtering of the target. It is shown that the refractive index of the SiO₂ film must be repeatedly corrected to minimize systematic errors. The results obtained can be used in the production of high-precision optical systems for various industries, especially medicine, space instrumentation, aviation and others.

The use of glass in microwave devices requires study of the dielectric properties of the material. We present the results of studying temperature and frequency dependences of the dielectric properties of quartz glass in the microwave region. The frequency dependence of the dielectric permittivity and dielectric loss tangent were determined using high-precision devices based on resonant cavity at a fixed frequency within a range of 8 – 26 GHz under a normal temperature. The temperature dependence was obtained using resonant cavity made of platinum coated quartz glass with a low thermal-expansion coefficient and insignificant change of intrinsic parameters under heating up to 1200°C. Experimental temperature and frequency dependences of the dielectric permittivity and dielectric loss tangent were obtained using classical conduction mechanisms taking into account the structural peculiarities of quartz glass. The effect of ionic conductivity was also evaluated in quartz glass in the microwave region. The revealed changes in the temperature dependence of the permittivity do not exceed the measurement error. The results obtained can be used for practical application of quartz glass in radio-engineering devices.

Individual deformation diagrams of all materials on metal, non-metal, or composite base under static and cyclic load link stresses and strains. These diagrams are obtained in standard tensile, compression, torsion or bending tests of laboratory samples with the registration of forces and deformations of their working parts upon loading. The diagram for a single static deformation in the stress-strain coordinates in this case covers both the region of elastic deformations and the region of elastic-plastic deformation, when deformations are localized in the neck of the loaded sample up to the moment of its destruction at a critical stress level. It is shown that linear, fractional-linear and power approximation of the obtained deformation curve are widely used in the description of the obtained deformation diagrams. Direct experiments, the theory of dislocations and the statistical theory of strength confirm the priority of power approximation of considered diagrams. At the same time for all construction materials the generalized deformation diagram in relative coordinates is described by a single power equation with the individual hardening parameter which is determined experimentally or theoretically using the dependences linking data on the module of elasticity, yield stresses, strength, and ultimate plasticity of the material. Diagrams of a cyclic elastoplastic deformation in the form of loops of plastic hysteresis are recorded by analogy with static tension diagrams with «stress – strain» axes of in conditional and true relative values. The generalized deformation diagrams for a single static and cyclic loading form a scientific basis for construction of the generalized fatigue curve on the basis of deformation fracture criterion for a wide range of cycles to failure. An effective solution to the problems of strength and service life for the most complex engineering objects such as nuclear reactors, aircraft, rocket and space systems can be achieved through introduction of generalized deformation and fracture diagrams into consideration and corresponding calculations. Their significance will especially increase in the design and implementation of new unique science-intensive facilities.

Economic efficiency in the operation of aircraft local air lines (LA) can be improved by increasing the awareness of the loading and aircraft structure integrity, with the subsequent adjustment of the maintenance program in accordance with the actual operating conditions. The allowance for specific features of loading load-bearing elements at transport aircraft during particular operations provides a significant extending in the safe life (in some cases, by several times). However, at the moment, load monitoring systems in the aviation industry have not yet been implemented universally. The implementation of the well-known approaches developed for monitoring and analyzing loads requires significant changes in the programs and procedures for maintaining airworthiness, including the need to install additional sophisticated measuring equipment. We propose an alternative approach to existing methods of load monitoring without using additional measuring equipment. The main stage is formation of the relationship between the flight parameters recorded by the standard on-board recorder and the loading parameters, which are determined by computational and experimental methods as a result of processing strain gauge data. A sufficient bulk of the strain data is usually obtained during the flight tests at the certification stage. Testing of this technique is considered with reference to the example of the loads in the elements of high lift devices of aircraft flaps. The average error in the estimates of the forces in the connecting rods of the inner flaps does not exceed 6%. The results obtained make it possible to determine with the acceptable accuracy the individual accumulated damageability of an aircraft structure and to assess the residual safe life. The presented approach is a part of the methodological framework necessary for the development and implementation of modern means of analyzing the integrity of the structure, implemented on the basis of on-board monitoring systems of local airlines aircraft.

The possibility of using profilometry for determining the duration of the incubation period of polymeric materials upon their testing for cavitation wear is considered. Six polymeric materials were tested for cavitation wear: plexiglass, fluoroplastic, low-pressure polyethylene, caprolon, Thordon SXL polymer, and epoxy compound. All the polymers were tested in fresh water kept at 20 ± 3°C, using an ultrasonic magnetostrictive vibrator, the vibration frequency and amplitude of the device horn butt were 22 kHz and 28 μm, respectively. The distance between horn butt and the butt-end surface of the cylindrical polymer sample was set at 0.50 mm. The samples were periodically weighed during testing, the roughness of their worn surface was evaluated, and sample mass loss and arithmetical mean deviation of the assessed profile of its surface were plotted as a function of the test duration. Like the cavitation wear of metals, the cavitation wear of polymers is also characterized by the presence of an incubation period, during which the separation of the wear particles from the sample surface does not take place yet. It is shown, that determination of the incubation period from the dependence of the mass loss vs test duration distinguishes is rather laborious, and, moreover, is accompanied by large errors due to water absorption. The use of profilometry was proposed to shorten the time and increase the accuracy of the determination of the incubation period of the cavitation wear of polymers. The arithmetical mean deviation of the profile of the surface under study is measures periodically during testing for cavitation wear. The duration of the incubation period is determined using the dependence of the arithmetic mean deviation of the wear surface profile on the duration of the cavitation impact by the abscissa of the point, in which the monotony and(or) smoothness of the dependence (plot) is violated.

The use of regression analysis in dynamic problems of system estimation requires a high-speed algorithm of model parameter determination. Moreover, the original data may have stochastic heterogeneity which entails the necessity of the estimates of model parameters be resistant to various data anomalies. However, stable estimation methods, including the least absolute deviations method, are significantly inferior to the parametric ones. The goal of the study is to describe a computationally efficient algorithm for implementing the method of least absolute deviations for dynamic estimation of regression models and to study its capabilities for solving practical problems. This algorithm is based on descending along nodal lines. In this case, instead of the values of the objective function, its derivative in the direction of descent is considered. The computational complexity of the algorithm is also reduced due to the use of the solution of the problem at the previous step as a starting point and efficient updating of observations in the current data sample. The external performance of the proposed dynamic version of the algorithm of gradient descent along nodal lines has been compared with the static version and with the least squares method. It is shown that the dynamic version of the algorithm of gradient descent along the nodal lines make it possible to bring the speed close to that of the least squares method for common practical situations and to use the proposed version in dynamic estimation problems for a wide class of systems.