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.     

Processor control in computerized data-acquisition systems

A method is proposed for detecting single and double processor errors during arithmetic and logicaloperations with reduced time consumption.     

Quantitative Characteristics of Binding of Metal Ions by Polyamide Fibres

Based on the data on chemical binding of the salts of ten metals from aqueous solutions by polycaproamide fibres, the metal cations were divided into four groups as a function of the concentration of the salt solutions and their chemisorption power. Copper cations are most prone to chemisorption by PCA fibres and their chemisorption index is one order of magnitude higher than the index for cations of the other metals.     

Complex surface modification of carbide tool by Nb + Hf + Ti alloying followed by hardfacing (Ti + Al)N

The surface of the WC/Co carbide tool was modified by an electron beam with the magnetron sputtering of Nb + Hf + Ti alloy to obtain a gradient interlayer before hardfacing with (Ti + Al)N. The results of investigations of the composite using a scanning electron microscope equipped with a device for X-ray energy dispersion spectroscopy are given. The results of the comparative mechanical tests show reduced wear rate.     

Migration of α-tocopherol from LDPE films to corn oil and its effect on the oxidative stability

The migration of α-tocopherol (α-T) from low density polyethylene (LDPE) films, added with 20 (film A) and 40 mg g^?1 (film B) to corn oil for 12 weeks at 5, 20 and 30 °C was determined. A LDPE film added with no α-T was used as control (film C). Diffusion coefficient (D) values for the film A system were 1.4 × 10^?11, 7.1 × 10^?11 and 30.3 × 10^?11 cm² s^?1 at 5, 20 and 30 °C, respectively. Meanwhile, D values for the film B system were 1.3 × 10^?11, 9.6 × 10^?11 and 51.1 × 10^?11 cm² s^?1 at the same temperatures. The activation energy (E_a) for the diffusion of α-T was 126.5 (film A) and 105.9 kJ mol^?1 (film B). The effect of the migration of α-T on the oxidative stability of corn oil was evaluated by monitoring hexanal content by solid phase micro-extraction (SPME) and gas chromatography. The hexanal content in the oil showed that both films added with α-T resulted suitable to maintain the oxidative stability of the oil for about 16 weeks at 30 °C, compared to 12 weeks for the oil in contact with the film C.     

Study of Metal Strained State During Workpiece Reduction in a Three-Roll Screw-Rolling Mill

Metallurgist - Results are given for a study of metal deformation state with screw rolling in a three-roll mill by means of computer modeling. Quantitative characteristics are obtained for the...