Modeling a Stress Condition of Ore Massif in the Process of Bauxite Deposits Development in the Mines of "Sevuralboksitruda"

The publication examines the problems of concentrator of elevated tension formation in pillars and ore massif. The article presents the results of modeling the stress state of interchamber pillars and ore deposits, using specialized geomechanical software PRESS 3D URAL. In the process of numerical experiments, it was found that the increase of natural flexibility in pillars leads to a decrease of normal stresses in comparison with the variant of a stiff scheme. If interchamber pillar involves different varieties of ores, there is a redistribution of stress on the site with more stiff ores. The article shows that the stress state control of interchamber pillars and ore massif in conditions of OJSC "Sevuralboxitruda" can be achieved by drilling relief holes

Simulation of Transcendental Deformation Mode of Interchamber Pillars and Ore Deposit in the Course of Development of Bauxite Resources at Great Depth on the Example of Mine "Sevuralboksitruda"

The publication describes the problem of transcendental deformation mode of interchamber pillar and ore deposit associated with the formation of hazardous zones in the rock mass in process of development of rockburst-hazardous rock masses at the great depth. Geomechanical software PRESS 3D URAL is used to assess the impact of the range of geological and technological factors on the mode of interchamber pillars deformation and ore deposit. The software allows to solve spatial problems in the elastic-plastic formulation. The results of step-by-step modeling of different mining and technical situations with a test of the bearing capacity of interchamber pillars showed that some of them can't withstand the mountain pressure and go to the transcendental mode of deformation with subsequent destruction. Identification of the destroyed pillars allows to adjust the boundary conditions of loading the ore mass. At the same time the neglect of transcendental mode of deformation of interchamber pillars can lead to an undervaluation of the stress level in the ore mass by 1.5 or more times. This can lead to an error in predicting the parameters of zones dangerous due to rock bumps

Freezing-out of heavy isotopes of Kr

The separation of isotopes of natural Krypton at the gas-liquid and liquid-solid phase interfaces was studied under nonequilibrium conditions using a cryogenic cell and mass spectrometry. The formation of condensate upon cooling Kr from the ambient temperature begins at an equilibrium temperature, which corresponds to the partial pressure of the dominant isotope 84Kr, and is accompanied by depletion of the gas phase 84Kr with a separation coefficient of ~0.92; but the isotopic composition returns to the original under conditions close to equilibrium. The formation of a solid phase near the freezing point is accompanied by depletion of the gas phase by heavy isotopes. The separation coefficients 86Kr and 84Kr are ~2 and ~12, respectively, when ~3.2% of the atoms pass into the solid phase. The solid phase with its fraction below 8.8%, 5.8% and 5.7% does not contain 80Kr, 82Kr and 83Kr with separation coefficients above ~90, ~110 and ~70, respectively, to compensate for the enrichment of the gas and liquid phases. Pressure-selective condensation can be used to separate components with close boiling points when distillation and temperature-selective condensation methods are ineffective, and freezing-out of heavy isotopes can be used to enrich elements with practically important isotopes.Comment: 11 pages; 3 Figures; 3 Tables; 26 Reference

Orientational Order-Disorder Effects in Molecular Crystals as Evidenced by Low-Frequency Raman Spectra

The studies of reorientational motions of molecules in crystals of organic compounds by low-frequency Raman spectroscopy are briefly reported. Some examples illustrate the efficiency of the investigation of order-disorder phenomena in organic crystals by the temperature dependence of low-frequency vibrational spectra combined with simultaneous calculations of the molecular dynamics by the atom-atom potentials (AAP) method. The conditions have been determined which are necessary in order to affect the low-frequency Raman spectra by anisotropy of molecular reorientations in crystals

Possibility of local pair existence in optimally doped SmFeAsO(1-x) in pseudogap regime

We report the analysis of pseudogap Delta* derived from resistivity experiments in FeAs-based superconductor SmFeAsO(0.85), having a critical temperature T_c = 55 K. Rather specific dependence Delta*(T) with two representative temperatures followed by a minimum at about 120 K was observed. Below T_s = 147 K, corresponding to the structural transition in SmFeAsO, Delta*(T) decreases linearly down to the temperature T_AFM = 133 K. This last peculiarity can likely be attributed to the antiferromagnetic (AFM) ordering of Fe spins. It is believed that the found behavior can be explained in terms of Machida, Nokura, and Matsubara (MNM) theory developed for the AFM superconductors.Comment: 5 pages, 2 figure

On a functional differential equation

© 2017, Pleiades Publishing, Ltd.Conditions for the existence and uniqueness of a solution to a problem for a functional differential equation are presented. A special case of this equation is a functional differential equation derived previously by the authors for the distribution density of the brightness of light in interstellar space in the case of several clouds uniformly distributed in the equatorial plane of the Galaxy and having different optical densities