An Electrodynamic Pulsed Valve for Molecular Beams

The pulsed valve with an electromagnetic drive, based on a permanent magnet and a movable coil, is intended to obtain pulsed molecular beams. It is controlled by small currents of a few amperes and, thus, does not produce considerable electrodynamic disturbances. An electric control circuit of the valve provides for reduced mechanical stress on the movable coil. The frequency of the valve actuation is controlled in a range of 5–50 Hz; the gas pulse duration is regulated within the limits of 0.2–4 ms (FWHM). This device is suggested for application in the spectroscopy of complex molecules in molecular beams.     

GaAs in GaSb: Strained nanostructures for mid-infrared optoelectronics

Molecular beam epitaxy was used for the first time to grow novel GaAs/GaSb heterostructures with ultrathin (0.8–3 monolayers) GaAs layers embedded in GaSb. These structures were studied by X-ray diffraction, transmission electron microscopy, and photoluminescence. By contrast to known structures with self-assembled quantum dots, GaAs layers in GaAs/GaSb structures are subject to elastic tensile stresses due to 7% lattice mismatch. The structures exhibit intense photoluminescence in the 2 μm region at low temperatures. Quantum-dimensional islands are formed in the structure at a nominal GaAs layer thickness exceeding 1.5 monolayers. The band alignment of the structures is of type II. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 36, No. 7, 2002, pp. 869–873. Original Russian Text Copyright ? 2002 by Solov’ev, Toropov, Meltser, Terent’ev, Kyutt, Sitnikova, Semenov, Ivanov, Motlan, Goldys, Kop’ev.     

A Vector Problem of Optimal Control in a Hilbert Space

The solvability of general vector problems of singular optimal control of linear distributed systems is investigated. The necessary conditions of efficiency of solutions are established and proved. The concept of approximative efficiency is considered and, based on the vector analysis of the Ekeland principle, the conditions of approximative efficiency are proved in the form of variational inequalities.__________Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 117–130, March–April 2005.     

Phase Composition of Copper Sulfide Films Produced from Copper Salt–Thiourea Complexes

Copper sulfide films were deposited by spray pyrolysis using aqueous solutions of copper salt–thiourea complexes. The phase composition of the deposits was shown to depend on the nature of the precursor complex, which is governed by the anion of the copper salt and, accordingly, the redox reactions in the starting solution.     

Involutive divisions and monomial orderings: Part II

This paper is a sequel to the studies on classification properties of involutive divisions reported in [1]. An example is given in which the minimal involutive basis of a particular monomial ideal for the “Janet antipode” <-division is neither an involutive Janet basis nor a minimal basis for a Janet-like division for any of n! orderings of variables. This example disproves the hypothesis that the minimal involutive basis for continuous and constructive divisions always coincides with the Janet basis for some ordering of variables.     

Liquidating a hard-to-reach high-level waste repository at the Kurchatov Institute

Details of organizing the work to liquidate a hard-to-reach repository for high-level waste at a special site at the Institute are described. The bulk of the waste in the pit was encased in a high-strength concrete slab and, together with low- and medium-level waste, contained a large number of metal cans of high-level waste. Special arrangements for radiation protection set up around the pit and the techniques used to break up the concrete casing and extract the waste are described. Video cameras and a gamma visualizer were used to find high-level waste and fragments in the demolished concrete casing and to guide remotely controlled robotic equipment to them. Changes in the radiation environment in the work area were monitored operationally with a gamma locator; data from this detector were fed in real time to and analyzed and processed by a personal computer for use in carrying out the work. Translated from Atomnaya énergiya, Vol. 105, No. 3, pp. 164–169, September, 2008.