Bulk large-area GaN layers

Mirror-smooth, transparent bulk GaN layers with an area of 2×3 cm² and a thickness of up to 1 mm were grown by hydrochloride vapor-phase epitaxy. Cracking of the material was eliminated by using a two-stage growth process; separation from a substrate was provided by a low-temperature buffer layer of preset thickness. For the best samples, FWHM of the X-ray rocking curve was ω_θ=3.5′ and the dislocation density amounted to 10⁷–10⁸ cm⁻².     

Tests of membrane-sorption decontamination of the reservoir cascade of the Techa river

Results are reported from a comprehensive test, under real conditions, of technology for removal of ⁹⁰Sr from the waters of the Techa reservoir cascade. This technology includes stages of preliminary decontamination, ion exchange softening with desorption and carbonate precipitation of hardening salts and ⁹⁰Sr from the desorbates, sorption cleanup on natural zeolites, and concentration of the strontium-containing carbonate precipitates. After the precipitates are removed, the solutions are reused in the desorption stage. The quality of the decontaminated water meets all the requirements for discharge into open drainage network in terms of all indicators. (The specific activity of ⁹⁰Sr is 3–5 Bq/liter in the filtrates.) The ⁹⁰Sr is concentrated by a factor of about 900 as solid radioactive waste in the form of a sediment with a moisture content of 50% and by about 1700 as air-dried solids. As a preliminary estimate, the operating cost of decontaminating 1 m³ of water in the V-11 reservoir is 200 rubles. Translated from Atomnaya énergiya, Vol. 105, No. 5, pp. 278–285, November, 2008.     

Conditions for the existence of backward surface magnetostatic waves in a ferrite-insulator-metal structure

A theoretical analysis is made of the dispersion of surface magnetostatic waves (SMSWs) at different frequencies propagating in ferrite-insulator-metal (FIM) structures magnetized by a uniform magnetic field. It is established that depending on the ratio between the thicknesses of the ferrite and insulating layers in FIM structures, backward SMSWs exist in different frequency ranges and have different wave numbers and directions of propagation. The conditions for which backward SMSWs may be observed directly in FIM structures are determined. Pis’ma Zh. Tekh. Fiz. 24, 1–7 (July 12, 1998)     

Structural peculiarities of 4H-SiC irradiated by Bi ions

X-ray diffraction, photoluminescence, micro-cathodoluminescence, and scanning and transmission electron spectroscopy were used to study the 710 MeV Bi ion irradiation effect in the fluence range of 1.4 × 10⁹−5 × 10¹⁰ cm⁻² on the structural and optical characteristics of pure high-resistivity n-type 4H-SiC epitaxial layers grown by chemical vapor deposition. It was established that the distribution of structural damage along the ion trajectory follows the computed profile of radiation defects formed in elastic collisions. The high-density ionization effect on the material characteristics has not been found under the irradiation conditions used. Optical methods revealed a wide spectrum of radiation-induced defects, with some of them contributing to the recombination process. The damaged 4H-SiC crystal lattice party recovers after annealing at 500°C. The text was submitted by the authors in English.     

Investigation of stress-strain states of a rubber-cord shell

The technique of determining the mechanical properties of materials of a rubber-cord shell that serves as an elastic element of a coupling clutch is described. The stress-strain state of the shell is investigated. It is shown that the most deformed shell regions, in which cracks arise under cyclic load, are located near the contours of pinching flanges. The composite cord is the most stressed element of the clutch and accepts more than two thirds of the load.     

Thermohydraulic characteristics and steam and gas distribution in an inclined thermosiphon

The results of experiments with thermosiphons inclined by 1.5–21° with respect to the horizon are given. Generalizing equations for determining some thermohydraulic characteristics of thermosiphons are proposed.     

Thermohydraulic processes in a heat pipe with a central circulation insert at low pressure

Results are given of an experimental investigation of thermohydraulic processes occurring in a compact natural-circulation loop (heat pipe with a central circulation insert) at a low pressure of steam-water mixture, including low vacuum p _top = 22–176 kPa. Consideration is given to axial heat transfer in nonboiling water under conditions of bubbling mode of loop operation; to superheating of water, which rises up the adiabatic region, relative to the saturation temperature; and to true void fraction and hydrodynamic stability of natural circulation.     

Characteristics of radiation generated during the conversion of backward bulk magnetostatic waves into electromagnetic waves

The directivity diagram of electromagnetic waves, generated during the propagation of backward bulk magnetostatic waves (BMSWs) in a ferrite plate tangentially magnetized by a decreasing field has been calculated using a model of the accelerated motion of magnetic charges. It is shown that the directivity diagram consists of two lobes, which are symmetric with respect to the ferrite plate surface and tilted back relative to the direction of backward BMSW propagation.     

An experimental substantiation of the emergency cooldown system project for the KLT-40S reactor installation of a floating nuclear cogeneration station

Results from thermal-hydraulic tests of a full-scale module of the emergency cooldown system for a KLT-40S reactor installation are presented. The validity of the solutions adopted in its design is shown. Recommendations for calculating the heat transfer coefficients during steam flow condensation and condensate cooling are given.     

Two-Dimensional filtration

An algorithm for solving a filtration problem is described. A method for the linearization of the problem in small elements and the subsequent joining of solutions without violating the flow character and the law defining the process is shown. Examples of jet streams are presented.