The theory of the instability of a planar interface in a process of the phrase transformation

The theory of the instability of a planar interface during an isothermal phase transformation is developed. It is shown that for large times only perturbations with large wave length are essential. The amplitude of the deviation from a planar interface grows with time as an exponent, the argument of which is proportional to $\text{t}{}^{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}$ instead of the usual simple exponential law.     

Development of an electrical discharge in strongly overstressed gaps with a low air pressure

The time of switching, step length and delay time of a discharge were investigated in this present project, under the following experimental conditions: plain brass electrodes, two- to 20-fold overvoltage and air pressure 30 mm Hg. In addition, the relative intensity of bremsstrahlung from the anode was measured and the-quanta energy was determined by the radiation attenuation method in aluminum plates. It is suggested that such short delay times obtained can be explained first of all by the accelerated motion of electrons and secondly by the bremsstrahlung from the anode.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 61–65, January, 1973.     

Study of the Characteristics of Elementary Processes in a Chain Hydrogen Burning Reaction in Oxygen

The characteristics of possible chain explosive hydrogen burning reactions in an oxidizing medium are calculated on the potential energy surface. Specifically, reactions H₂ + O₂ → H₂O + O, H₂ + O₂ → HO₂ + H, and H₂ + O₂ → OH + OH are considered. Special attention is devoted to the production of a pair of fast highly reactive OH radicals. Because of the high activation threshold, this reaction is often excluded from the known kinetic scheme of hydrogen burning. However, a spread in estimates of kinetic characteristics and a disagreement between theoretical predictions with experimental results suggest that the kinetic scheme should be refined.     

Improvement of Image Spatial Resolution in Optoacoustic Tomography with the Use of a Confocal Array

The spatial resolution and size of the sensitivity area of tomographic systems are estimated by calculating sensitivity maps and spatial resolution maps in the image plane of complex arrays. The relation between the size of areas of high sensitivity and high spatial resolution for real-time oriented tomographic systems with confocal arrays is studied. It is shown that arrays with toroidal geometry significantly improve the diagnostic capabilities of optoacoustic and laser-ultrasound structural analysis of biological objects, rocks, and composite materials.     

Structural analysis of xCsCl(1 − x)Ga2S3 glasses

Sulphide glasses doped with rare-earth ions have been demonstrated to be suitable for photonic applications such as optical amplifiers, up-converters and fiber lasers. The substitution of metal halides into the glass network has been shown to result glasses with desirable properties in terms of quantum efficiency and fiber manufacture [J.R. Hector, J. Wang, D. Brady, M. Kluth, D.W. Hewak, W.S. Brocklesby, D.N. Payne, Journal of Non-Crystalline Solids 239 (1998) 176]. To assist in the understanding of this improvement a structural analysis of glasses with a composition xCsCl(1 ? x)Ga₂S₃ has been undertaken in order to examine the nature of the gallium environment. Information collected by high energy X-ray diffraction and neutron diffraction have been analyzed to permit the identification of the structural units as Ga centered tetrahedra. The interconnection between the tetrahedra was found to be predominantly corner sharing.     

Determination of the hydrogen diffusion coefficient in transformer oil

The hydrogen diffusion coefficient in transformer oil is determined by optically monitoring the dynamics of the hydrogen bubble dissolution in pure degassed oil. The diffusion coefficient is found to be roughly two orders of magnitude smaller than those determined earlier. This result is of great importance for chromatographic analysis of gases dissolved in transformer oil, since it gives grounds to suspect that hydrogen is not so volatile as implicitly believed in a number of works. Accordingly, the reliability of diagnostic data for high-voltage oil-filled equipment improves.