A modular bipolar power supply for high-power ion-plasma installations

The circuitry solutions, design, and main parameters of a modular pulse bipolar power-supply unit for high-power ion-plasma facilities are described. The modular principle of designing power supplies provided their application in various processes. The results of tests of the developed device as the power supply of a magnetron sputtering system with a power of 60 kW and a high-voltage power supply of the substrate bias voltage with a power of up to 40 kW are presented. The efficiency of applying bipolar pulses for preventing arcing at the magnetron cathode is experimentally demonstrated.     

Effect of fuel burnup on the effectiveness of ultrasonic detection of leaky fuel elements in VVER-1000 fuel assemblies

The effect of fuel burnup in VVER-1000 fuel elements on the utilization effectiveness of ultrasonic detection of leaky fuel elements is examined. It is determined that the limitations of this method are due to the interaction of fuel-element cladding with the fuel pellets. Threshold for fuel burnup in VVER-1000 fuel elements with E-110 alloy cladding, determining the application limits of ultrasonic detection of leaky fuel elements in fuel assemblies, is determined.     

Production and Emulsifying Effect of Polyglycerol and Fatty Acid Esters with Varying Degrees of Esterification

Esters with acyl groups can be formed by the esterification of polyglycerol. The purpose of the present study was to produce fatty acid esters [hexanoic (caproic), octanoic (caprylic), decanoic (capric), dodecanoic (lauric), tetradecanoic (myristic), hexadecanoic (palmitic), octadecanoic (stearic)] and polyglycerol (average number‐of degrees of polymerization of 5) with varying degrees of esterification and to examine their emulsifying properties. A number of fundamental catalysts of polyglycerol acylation reactions by methyl esters of carboxylic acid were studied, and sodium methoxide was found to be the best choice. The temperature rate of transesterification increased from 180 to 220 °C with the fatty acid chain alkyl residue. Synthesized mono‐, di‐, tri‐, tetra‐, and heptaesters of various fatty acids and polyglycerol provided the highest hydroxyl values from 15 to 815 mg KOH g^?1 and saponification values from 82 to 321 mg KOH g^?1. The emulsifying properties were assessed for all polyglycerol and fatty acid esters, with results showing maximum emulsifying effect for tri‐ and tetraesters of capric, lauric, and caprylic acids. Regardless of the hydrophilic–lipophilic balance value (HLB) of polyglycerol esters and carboxylic acid, a 4:1 ratio of sunflower oil to water formed a water‐in‐oil type emulsion. When mixing oil and water in a 1:1 ratio, mono‐ and diesters of polyglycerol formed an oil‐in‐water type emulsion, heptaesters formed a water‐in‐oil type emulsion, and tri‐ and tetraesters formed both of types of emulsions, depending on the length of the acid hydrocarbon radicals.     

Interpolyelectrolyte complexes of maleic acid copolymers and chitosan for stabilization and functionalization of magnetite nano‐ and microparticles

A facile method of preparation of stabilized and functionalized nano‐ and microparticles of magnetite by successive application of oppositely charged polymers with a regular structure of macromolecular chains (chitosan and maleic acid copolymers) onto Fe₃O₄ core are developed. This approach makes it possible to create two types of magnetite interpolyelectrolyte shells, containing carboxylic or amino groups in outer layer of shell. Composition and magnetic properties of composite particles depend on nature of the copolymer of maleic acid, reaction conditions and size of obtained particles. The carboxylic groups of copolymer in outer layer of interpolyelectrolyte shell were converted into reactive anhydride groups by heating. Thermal treatment also leads to covalent crosslinking of shell and improves stability of composites both in acidic and alkaline media. Horseradish peroxidase was successfully immobilized onto covalently crosslinked and activated microparticles of Fe₃O₄ in aqueous medium without of condensing agents. The proposed reproducible and low‐cost technique does not use toxic reagents or solvents at all stages, including preparation of Fe₃O₄, formation, activation and crosslinking, of magnetite shell, modification of activated surface of composite particles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39663.     

First-level Dulkyn gravitational wave detector

The functional-block diagram of the Dulkyn gravitational wave detector is described.     

Simplified scoring methods for HMM-based speech recognition

Most of the contemporary speech recognition systems exploit complex algorithms based on Hidden Markov Models (HMMs) to achieve high accuracy. However, in some cases rich computational resources are not available, and even isolated words recognition becomes challenging task. In this paper, we present two ways to simplify scoring in HMM-based speech recognition in order to reduce its computational complexity. We focus on core HMM procedure—forward algorithm, which is used to find the probability of generating observation sequence by given HMM, applying methods of dynamic programming. All proposed approaches were tested on Russian words recognition and the results were compared with those demonstrated by conventional forward algorithm.     

The electronic educational resource “Dynamics of Systems for Controlling Thermal Processes”

We present the results from the development of a cycle of tutorial laboratory works for remote education under the general title “Dynamics of Systems for Controlling Thermal Process” for students specializing in the discipline of automation of technological processes and production facilities worked out on the basis of the Matlab software package and the Simulink environment for development of simulation models.     

An ultrasonic method for the detection of leaking fuel elements in nuclear reactors

An ultrasonic method for the detection of leaking fuel elements in the structure of the fuel assembly of BBЭP-1000 water-water power reactors is considered. The method is intended for the detection of water passing through a cladding flaw into a fuel element. The calculation and experimental study data for the acoustic channel of the method and the results of testing on radiated fuel assemblies from the Kalinin and Balakovo Nuclear Power Plants are given. The high sensitivity of the developed method is shown experimentally. The boundaries of its applicability are determined.     

Production of isobutylene from acetone over micro–mesoporous catalysts

The production of isobutylene from acetone over micro–mesoporous catalysts with different mesopore contents, which have been prepared using hydrothermal recrystallization of mordenite (MOR) zeolite modified with cesium acetate by incipient wetness impregnation, has been studied. It has been shown that cesium is inserted into the cation positions during the modification, at the same time the number of Brønsted acid sites in the samples decreased. It has been found that an increase in the content of mesopores in the catalyst leads to an increase in the initial rates of acetone conversion and isobutylene formation as a result of removing diffusion limitations. Brønsted acid sites have been shown to be preferable for the selective production of isobutylene from acetone. Micro–mesoporous materials operate more stably as compared to microporous materials.     

Processing of spent molybdenum-bearing catalysts from petrochemical synthesis

Technologies for processing spent molybdenum-bearing catalysts from petrochemical production are reviewed. The degree of molybdenum-trioxide extraction from the spent catalysts is presented for different technologies. Pyrometallurgical and hydrometallurgical methods, when used individually, do not ensure the required molybdenum-trioxide extraction. The pros and cons of direct alloying of steel with spent catalysts through the slag phase are outlined. The processing of hydrometallurgically treated catalysts to obtain slag mixtures for steel refining is described. An optimal multistage processing method for the catalysts is considered. By that means, waste-free processing of the spent catalysts is possible. On that basis, calcium molybdate may be used instead of ferroalloys for steel treatment in the ladle–furnace unit.