Stability of imperfect conical shells with helical reinforcement

The article explains a method of numerical calculation of the stability of imperfect conical shells with helical reinforcement under uniform external pressure. It also investigates the effect of the amplitude of local initial imperfections on the critical loads.Translated from Problemy Prochnosti, No. 12, pp. 67–69, December, 1991.     

Shock wave reflection from the axis of symmetry in a nonuniform flow with the formation of a circulatory flow zone

Two supersonic axisymmetric flows, in which the incidence of a shock wave on the axis of symmetry leads to the formation of return (circulatory) flow zones, are numerically modeled. The former of these flows is of the wake type with a ram pressure deficit in the vicinity of the axis of symmetry. The numerical results obtained are in qualitative and quantitative agreement with the available experimental data. The latter flow is generated by a hypersonic spherically-symmetric source placed on the axis of a cylindrical channel. An analysis of the obtained solutions, together with their comparison with the data in the literature, suggests that the formation of the above-mentioned circulatory flow zones is physical, rather than computational, in nature. There is also reason to believe that the phenomenon under consideration is hydrodynamic, rather than dissipative, in nature.     

Composition and surface energy characteristics of new petroleum resins

We investigated the composition and surface energy properties—the surface free energy, acid–base and dispersive components, acid and base parameters (according to the van Oss–Chaudhury–Good method) and acidity parameter (according to the Berger method) for several types of aromatic petroleum resins (PR). We could see that the Berger, nonlinear systems, and spatial methods provide slightly different information about the acid–base properties of PRs. For acid–base properties, relevant proton content was determined for each sample by nuclear magnetic resonance spectroscopy. Correlations between the composition and surface characteristics of the studied aromatic PR have been revealed. According to the data obtained from the acid–base approach and nuclear magnetic resonance spectroscopy, we can predict the possible combinations of PR–polymer with the best interface interaction, which can lead to high mechanical properties. POLYM. ENG. SCI., 57:1028–1032, 2017. © 2016 Society of Plastics Engineers     

Investigation and development of the atlas of chromaticity for formation of raster elements and basic link fragments in synthesizing color halftone images

A direction of improvement of a method for formation of color images on offset plates is proposed. The method and tools developed for synthesizing color images are experimentally tested. Translated from Kibernetika i Sistemnyi Analiz, No. 3, pp. 99–109, May–June, 2000.     

Development of the FUMILI minimization package

The suggested FUMILI package development has the following advantages: a more convenient and friendly user interface; no limit on the number of parameters and experimental points; speed advantage when the number of parameters is high enough; there are options to ignore wrong experimental points and correct experimental errors. The preliminary scan is envisaged for complicated tasks.     

Processing of perovskite concentrate by ammonium hydrodifluoride

The results of studies of the hydrodifluoride leaching of the perovskite concentrate have been presented. It has been shown that processing the perovskite concentrate using fluoride technology enables one to transform niobium and tantalum into a solution, along with fluoroammonium salts of titanium, iron, and silicon, and to isolate rare-earth elements in the form of complex fluoroammonium salts mixed with CaF₂ within a few stages.