Identification of Objects During the Structural and System Monitoring of the Situation

Journal of Computer and Systems Sciences International - Using the criterion of the minimum average risk, the statistically optimal algorithm for identifying objects by the same type of parameters...     

The ortho-to-para conversion in solid hydrogen,catalyzed by hydrogen atoms

The combined techniques of ESR and NMR were used to investigate the process of ortho-para conversion in solid molecular hydrogen, containing small amounts ( 500 ppm) of hydrogen atoms as impurity. Although the impurity atoms catalyze the effective conversion of the neighboring ortho-H₂, the total catalyzed conversion rate at temperatures from 2.2 K to 4.4 K is much less than expected from the rate of the H atoms recombination. A possible explanation is given in terms of the diffusion of H atoms, which is confined to some defects in the crystal.     

Defect Structure of Alkaline-Earth,Cadmium, and Lead Titanates

X-ray powder diffraction, scanning electron microscopy, and x-ray microanalysis data indicate that Ba, Ca, Sr, Cd, and Pb titanates contain defect structures associated with crystallographic shear. Spatially periodic shear gives rise to modulated displacements of the Ti and O atoms across the shear plane, resulting in long-period structures. The parameters of such structures depend on the nature of the sample (single crystal, ceramic, or powder), its microstructure, and the crystal chemistry of the titanate.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 5, 2005, pp. 573–584.Original Russian Text Copyright © 2005 by Reznichenko, Shilkina, S. Titov, Razumovskaya, V. Titov, Shevtsov.     

Resource potential for wind-hydrogen power in Ukraine

The paper provides an assessment of the current wind energy potential in Ukraine, and discusses developmental prospects for wind-hydrogen power generation in the country. Hydrogen utilization is a highly promising option for Ukraine's energy system, environment, and business. In Ukraine, an optimal way towards clean zero-carbon energy production is through the development of the wind-hydrogen sector. In order to make it possible, the energy potential of industrial hydrogen production and use has to be studied thoroughly.Ukraine possesses huge resources for wind energy supply. At the beginning of 2020, the total installed capacity of Ukrainian wind farms was 1.17 GW. Wind power generation in Ukraine has significant advantages in comparison to the use of traditional sources such as thermal and nuclear energy.In this work, an assessment of the wind resource potential in Ukraine is made via the geographical approach suggested by the authors, and according to the «Methodical guidelines for the assessment of average annual power generation by a wind turbine based on the long-term wind speed observation data». The paper analyses the long-term dynamics of average annual wind speed at 40 Ukrainian weather stations that provide valid data. The parameter for the vertical wind profile model is calculated based on the data reanalysis for 10 m and 50 m altitudes. The capacity factor (CF) for modern wind turbine generators is determined. The CF spatial distribution for an average 3 MW wind turbine and the power generation potential for the wind power plants across the territory of Ukraine are mapped.Based on the wind energy potential assessment, the equivalent possible production of water electrolysis-derived green hydrogen is estimated. The potential average annual production of green hydrogen across the territory of Ukraine is mapped.It is concluded that Ukraine can potentially establish wind power plants with a total capacity of 688 GW on its territory. The average annual electricity production of this system is supposed to reach up to 2174 bln kWh. Thus, it can provide an average annual production of 483 billion Nm³ (43 million tons) of green hydrogen by electrolysis. The social efficiency of investments in wind-hydrogen electricity is presented.     

Stability of the structure of compact zirconium nitride ceramics to irradiation with high-energy xenon ions

X-ray diffraction and transmission electron microscopy (TEM) data demonstrate that irradiation with high-energy ⁺²⁴Xe¹³⁶ ions causes no changes in the grain microstructure of compact zirconium nitride ceramics. According to Raman spectroscopy and high-resolution TEM data, the irradiated ceramics may have local distortions of the zirconium nitride lattice within regions on the order of the lattice parameter in size.     

Competing topological phases in few-layer graphene

We investigate the effect of spin-orbit coupling on the band structure of graphene-based two-dimensional Dirac fermion gases in the quantum Hall regime. Taking monolayer graphene as our first candidate, we show that a quantum phase transition between two distinct topological states—the quantum Hall and the quantum spin Hall phases—can be driven by simply tuning the Fermi level with a gate voltage. This transition is characterized by the existence of a chiral spin-polarized edge state propagating along the interface separating the two topological phases. We then apply our analysis to the more difficult case of bilayer graphene. Unlike in monolayer graphene, spin-orbit coupling by itself has indeed been predicted to be unsuccessful in driving bilayer graphene into a topological phase, due to the existence of an even number of pairs of spin-polarized edge states. While we show that this remains the case in the quantum Hall regime, we point out that by additionally breaking the layer inversion symmetry, a non-trivial quantum spin Hall phase can re-emerge in bilayer graphene at low energy. We consider two different symmetry-breaking mechanisms: inducing spin-orbit coupling only in the upper layer, and applying a perpendicular electric field. In both cases, the presence at low energy of an odd number of pairs of edge states can be driven by an exchange field. The related situation in trilayer graphene is also discussed.