Prediction of flow about an oscillating airfoil in a wind tunnel with timeaccurateinlet and outlet conditions

Non‐local inlet and outlet transparent boundary conditions (TBCs) are incorporated into the FLOWer code and tested for transonic flow problems about an oscillatingai rfoil in a non‐adapted wind tunnel. We show that TBCs require much smaller sizes of the computational domain for solvingt he problem comparingt he FLOWer type characteristic based boundary conditions (CBCFs). Moreover, solutions obtained with TBCs and CBCFs for the oscillatingai rfoil can strongly di.er from each other in the case of the “resonance” reduced frequencies.     

Reaction of Metcar Ti8C12 with Halogen-Containing Addends

Ab initio electron density functional method in the discrete-variational scheme was used to perform self-consistent calculations of the electronic structure of Ti₈C₁₂Cl₂ and Ti₈C₁₂(CHCl₃), i.e., the adducts of reaction between the Ti₈C₁₂ metallocarbohedrene and halogen-containing addends (Cl₂ and CHCl₃ molecules). The electronic states, charge distributions, and chemical bonds of the obtained adducts were analyzed. The results were compared with calculations of the Ti₈C₁₂Cl complex that can be treated as a model of the destruction stage of the addends. General conditions for the interaction of halogenated addends with metcars in the molecular and crystalline states are discussed based on the data obtained.     

Electron spectrum of arsenic inclusions in gallium arsenide

Energy-band spectra are calculated for various modifications of coarse arsenic inclusions in gallium arsenide. Tomsk State Pedagogical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 93–97, July, 1998.     

Electronic properties of single-walled V2O5 nanotubes

Atomistic models of quasi-one-dimensional vanadium pentoxide nanostructures—single-walled nanotubes formed by rolling (010) layers of V₂O₅ are constructed and their electronic properties and bond indices are studied using the tight-binding band method. We show that all zigzag (n,0)- and armchair (n,n)-like nanotubes are uniformly semiconducting, and the band gap trends to vanish as the tube diameters decrease. The V-O covalent bonds were found to be the strongest interactions in V₂O₅ tubes, whereas V-V bonds proved to be much weaker.     

Statistics of the fragments forming with the destruction of solids by explosion

The article sets forth one of the possible approaches to the construction of a size distribution function of the fragments. The Rozin-Rammler law for the distribution is obtained from general theoretical probability consideration. The theoretically obtained distribution function was verified in a large number of experiments. The experimental data are in good agreement with the theoretical deductions.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 2, pp. 87–100, March–April, 1971.     

Some characteristic features of formation of composite material based on KDP single crystal with incorporated Al2O3·nH2O nanoparticles

Composite material based on KDP (KH₂PO₄) crystal matrix with incorporated aluminum oxyhydroxide Al₂O₃·nH₂O nanoparticles is obtained and peculiarities of the formation of KDP:Al₂O₃·nH₂O composite structure are studied by selective etching, optical and scanning electron microscopy. Influence of the nanoparticles on the formation of defect subsystem is analyzed. The obtained material is shown to have a zonal structure with a period independent of the concentration of nanoparticles. By means of FTIR‐spectroscopy, interaction of nanoparticles with KH₂PO₄ solution is studied. A model of the capture of nanoparticles by the {100} KDP crystal face is proposed.     

Mirror nesting of the Fermi contour and zero line of the superconducting order parameter

The superconducting order parameter that emerges owing to pairing of charge carriers with a large total momentum of the pair during screened Coulomb repulsion in a degenerate quasi-two-dimensional electronic system is determined as a function of the momentum of relative motion of the pair. In view of the kinematic constraint associated with Fermi filling, the ordered state exists in a limited domain of the momentum space, the shape and size of this domain being determined by the total momentum of the pair. The order parameter is not a constant-sign function of the momentum and reverses its sign on a certain line in a kinematically allowed domain. Superconducting instability arises for an arbitrarily small value of the repulsive interaction for certain momenta of the pair, for which the mirror nesting condition is satisfied; this results in the formation of a pair Fermi contour, i.e., the line of coincidence of segments of the Fermi contour with the isoline of the kinetic energy of relative motion of the pair. The temperature dependence of the superconducting order parameter is studied. Owing to the proximity effect in the momentum space, superconducting ordering is extended to the kinematically forbidden domain.     

Emission of terahertz radiation from selectively doped AlGaN/GaN heterostructures under the heating of two-dimensional electrons by an electric field

The emission of terahertz radiation from a AlGaN/GaN heterostructure under the heating of two-dimensional electrons in a lateral electric field is studied. The field dependence of the temperature of hot electrons is determined from an analysis of experimental volt-ampere characteristics. A theoretical model of the thermal radiation of hot two-dimensional electrons is considered, and the calculation results are compared with an experiment on terahertz radiation emission.