Generalized Catalan numbers in problems of processing of random discrete images

The notion of the Catalan numerical sequence is extended. Problems leading to generalized Catalan numbers are formulated and solved.     

Piezoelectric effect in GaAs nanowires

The anomalous piezoelectric effect in GaAs nanowires was detected (the piezoelectric module d ₃₃ ≈ 26 pC/N). This result can be explained by the dominant content of the phase with the wurtzite-type crystal structure in GaAs nanowires and an increased pressing force on the contact layer.     

Acoustic emission in hafnium under tensile deformation

The paper addresses the dependence of acoustic emission produced in rolled hafnium GFé-1 under tensile deformation on the material’s structural state. A correlation has been established between the material structure, the level of mechanical properties and the values of acoustic parameters. Acoustic emission in non-recrystallized hafnium under tensile deformation is recorded only at the stages that precede fracture. Upon recrystallization annealing at temperatures of 1123 and 1373 K acoustic emission occurs at all the stages of tensile deformation. The highest level of acoustic emission activity in hafnium is observed during the transition from elastic to elastic-plastic strain.     

Peculiarities of volt-ampere characteristics of a tungsten cathode in a high-current arc

A model making it possible to calculate the emission currents in a cathode and its volt-ampere characteristic (VAC) taking the phenomena in the near-cathode plasma layer into account is proposed. The effect of plasma electrons and ions, thermal field-emission processes, and radiation from the plasma and evaporation of the cathode material are taken into account. The fields of the electrical potential and temperature in the cathode body, with the Joule heat release taken into account, are calculated. The numerical simulation yielded the conditions causing the volt-ampere characteristic ambiguity in the near-cathode layer in the absence of a liquid cathode spot. The obtained characteristics make it possible to estimate the lifetime and efficiency of a plasmotron with a tungsten cathode and argon serving as an actuating medium used in a number of plasma technologies.     

Synthesis of vanadium dioxide films by a modified sol-gel process

Vanadium dioxide films have been grown on silicon substrates and on SiO₂ layers on silicon by a modified sol-gel process using methyl cellosolve as a solvent. We have failed to obtain vanadium dioxide layers on Pt/TiO _x /SiO₂/Si substrates. For all of the substrates studied, we have examined the effect of synthesis conditions (initial solution concentration, deposition procedure, and oxidation and reduction anneals) on the phase composition, thickness, and surface morphology of the films.     

Kinetic processes in the plasma formed in combustion of hydrocarbon fuels

An analysis of the basic kinetic processes responsible for the formation of ions, electrons, charged and neutral carbon clusters and particles of nanometer size in the combustion of hydrocarbon fuels has been made. It has been shown that the formation of a polydisperse ensemble of positively and negatively charged particles is mainly caused by the ion adhesion to primary particles and secondarily formed particles and also by particle coagulation. Account must be taken not only of the Coulomb interaction but also of the van der Waals and polarization interaction between particles. The distinstice features of the deposition of polar molecules on charged particles have been considered.     

Secondary diffraction of diffracted Gaussian beam of laser radiation

The diffraction of a narrow Gaussian beam of laser radiation on mutually perpendicular edges of crossed, superimposed sharp wedge-shaped blades (safety razors) has been studied. The diffraction pattern observed on a flat screen behind the blades comprises a very bright central spot, which exhibits the structure of a “light network” with rectangular cells, and four groups of narrow bright bands that expand from the central spot toward the periphery and form a rectangular cross. The spatial frequency of light-field modulation on the screen can be controlled by varying the distance from the blades to screen.     

Infrared focal plane assemblies based on HgCdTe/Si(310) heterostructure

It is demonstrated for the first time that high-performance scanning infrared (IR) focal plane assemblies of the 288 × 4 format for long-wavelength (8–12 μm) IR spectral range can be created based on a Cd _x Hg_{1 − x} Te/Si(310) heterostructure.     

Effect of complexing agents (DTPA and oxalic acid) on the extraction behavior of technetium in the TBP-N2H5NO3-HNO3 system

The effect of complexing agents DTPA and H₂C₂O₄ on the extraction-chemical behavior of Tc, as applied to extractive splitting of U and Pu in the Purex process, was studied. The kinetic relationships of catalytic decomposition of N₂H₅NO₃ under the action of Tc in the presence of these agents were determined. Variation of the ratio of the oxidized and reduced Tc species in the course of this process at various HNO₃ concentrations was examined. In the final step of the reaction of N₂H₅NO₃ with Tc in a nitric acid solution, when the reductant content is stabilized, the oxidation of reduced Tc also stops or continues at a considerably lower rate than before stabilization. The presence of DTPA decreases the rate of Tc(IV) oxidation owing to its binding in a complex and decreases the fraction of Tc(VII) in the system by the end of the reaction, with no decrease in the rate of N₂H₅NO₃ decomposition noted under these conditions. The presence of H₂C₂O₄ in solutions decelerates the Tc reduction and the N₂H₅NO₃ decomposition; the oxidation of the reduced Tc either is insignificant or is not observed at all, depending on the conditions and H₂C₂O₄ content.