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Theoretical and experimental data on the concentrations of methane in different phase states in the porous structure of coals from the Donets Basin are reported. On the saturation of coal samples with methane, the natural conditions of the occurrence of methane in coal beds were simulated for the equilibrium coal–gas system. The amounts of methane dissolved in a solid matrix and adsorbed on the pore surfaces of coal matter were measured by broad-band NMR spectroscopy. The values obtained did not exceed 20% of the total methane absorbed by the sample in an equilibrium state at a pressure of 10 MPa. Sorbed methane was the predominant phase state only upon the opening of a high-pressure chamber after the emission of methane from filtration channels.

The state and operation quality of sets of submersible electrical equipment (SEE) at oil wells as a complex engineering system depends on the fault-free and reliable operation of downhole equipment components. Oil production SEE, especially submersible electric motors (SEM) are subjected to various external factors and impacts and they are used in various operating modes. To obtain the data on the state of SEE, we used statistics for the failures during operation. This valid method for the analysis of the conditions of the engineering facilities in the industry is, in most cases, the only suitable one for the mathematic functional and quantitative description of reliability, including the SEE cycles to failure parameter. We collected and analyzed the data on technological failures at oil production facilities and established a database for relevant statistics on the use of SEE (for 2014-2019). We present the results of the statistical analysis for the correct representation of the current conditions of the SEE (including SEM). We used them to produce a systematized assessment of the current state of SEM using smart analysis and probabilistic statistical modeling. We identified and ranked the factors resulting in technological failures, formulated a set of technical and organizational actions to minimize them, and improve the reliability and operation readiness of the SEE.

We formulated a paradox in the theory of turbulent premixed flame in the flamelet regime: discrepancy between the Damkohler (1940) and Shelkin (1943) estimate of the turbulence flame speed \(U_{t} \sim {u}^{\prime }\) in the case of strong turbulence (\({u}^{\prime }>>S_{L} \)) and numerous experiments that show a strong dependence of Ut on the speed of the instantaneous flame SL. We name this discrepancy the Damkohler-Shelkin paradox. The first aim of the research is to validate and clarify this estimate, which is based on intuitive considerations, as the paradox must be a statement that seems contradictory to observations but is actually true. We analysed the turbulent flame in the context of the original hyperbolic combustion equation that directly describes the leading edge of the flame, which is a locus of the Zel’dovich “leading points” controlling the speed of the turbulent flame. Analysis of the corresponding characteristic equations results in the expression for speed on the steady-state turbulent flame \(U_{t} ={u}^{\prime }\sqrt {1+(S_{L} /{u}^{\prime })^{2}} \), which is the case when \({u}^{\prime }>>S_{L} \) becomes \(U_{t} \cong {u}^{\prime }\). This result confirms and improves the Damkohler-Shelkin estimate \(U_{t} \sim {u}^{\prime }\). The second aim is to resolve the Damkohler-Shelkin paradox. We explain the discrepancy with observations by the fact that turbulent flames are transient due to insufficient residence time in the real burners to reach statistical equilibrium of wrinkle structures of the random flame surface. We consider the transient flame in the intermediate asymptotic stage when the small-scales wrinkles are in statistical equilibrium, while at the same time the large-scale wrinkles are far from equilibrium. The expressions for the flame speed and width, which we deduce using the dimensional analysis and general properties of the ransom surface, \(U_{t} \sim ({u}^{\prime }S_{L})^{1/2}\) and \(\delta _{t} \sim ({u}^{\prime }Lt)^{1/2}\), show that this transient flame is in fact a turbulent mixing layer travelling with constant speed Ut depending on SL, the intermediate steady propagation (ISP) flame. Qualitative estimations of the times required for the small-scale and large-scale wrinkles to reach statistical equilibrium show that the turbulent Bunsen- and V-flames correspond to the intermediated asymptotic stage, and the turbulent flames with a complete equilibrium structure of the wrinkled flamelet surface are not attainable under laboratory conditions. We present the results of numerical simulations of the impingent flames, which count in favour of the belief that these flames are also transient.

Methods of calculating the nuclear reactor reactivity from the measured time-dependence of the neutron flux are discussed. It is noted that the corresponding problems for the direct and inverse equations of point kinetics in the approximation of a prompt-jump change of neutron flux are not equivalent, which is expressed in that the reactivity values in these problems do not coincide with one another. The reasons for the nonequivalence and ways of its elimination are investigated. New equations of inverse point kinetics without this deficiency are proposed. It is shown that the proposed equations give the correct reactivity immediately after the onset of a perturbation in the reactor and not asymptotically as in the case of the conventional equations.

Abstract The possibility of lasing on the Sr II ion transition 6 2 S 1 2 → 5 2 P 3 2 at λ = 4305 A in a plasma generated by a shower of fragments formed as a result of nuclear reactions has been considered. Calculations show that a relatively large gain can be obtained at a neutron flux j n > 10 16 n/cm 2 s, when using the 3 He isotope for the pumping.

The degradation of nanodimensional platinum catalysts in concentrated phosphoric acid and the related changes in the kinetics of cathodic oxygen reduction have been studied in the course of accelerated corrosion tests. The results of structural and electrochemical investigations showed that the stability of such electrocatalytical systems substantially depends on the type of supporting carbon and the metal phase composition.

We consider the problems of developing a decision making system intended to improve the efficiency of servicing processes for electrotechnical equipment according to its current technical condition. We emphasize the development of adaptive short-term forecasting as one of the key elements in this system.

The paper examines theoretical relationships for the compaction of an ultradisperse material in the channel of a die with consideration of possible variation in the coefficient of lateral pressure, as applies to drawing with allowance for mobility of the channel wall. Translated from Khimicheskoe i Neftegazovoe Mashinostroenie, No. 9, pp. 3–6, September, 2010.

Apart from subjecting metal to nondestructive testing and determining its actual state, which are the traditional methods used for managing the service life of NPP equipment during its operation, other approaches closely linked with rendering engineering support to NPP operation have emerged in recent decades, which, however, have been covered in publications to a lesser extent. Service life management matters occupy the central place in the structure of engineering support measures. Application of the concept of repairing NPP equipment based on assessing its technical state and the risk of its failure makes it possible to achieve significantly smaller costs for maintenance and repairs and produce a larger amount of electricity due to shorter planned outages. Decreasing the occurrence probability of a process-related abnormality through its prediction is a further development of techniques for monitoring the technical state of equipment and systems. The proposed and implemented procedure for predicting the occurrence of process-related deviations from normal NPP operation opens the possibility to record in the online mode the trends in changes of process parameters that are likely to lead to malfunctions in equipment operation and to reduce the probability of power unit unloading when an abnormal technical state of equipment occurs and develops by recording changes in the state at an early stage and taking timely corrective measures. The article presents the structure of interconnections between the objectives and conditions of adjustment and commissioning tests, in which the management of equipment service life (saving and optimizing the service life) occupies the central place. Special attention is paid to differences in resource saving and optimization measures.