Simulation of heat-transfer processes and assessment of the viscoplastic parameters of iron ore in blast furnaces

Stages in the development of an information and simulation system for assessing the position and shape of the viscoplastic iron-ore zone (the cohesion zone) in the blast furnace are outlined. This system also permits diagnostics of the zone's optimal configuration on the basis of available operational information for the furnace in the baseline period. In addition, the system proves useful during the design period, with variation in the smelting parameters. The capabilities of the corresponding software are discussed, and its use in blast-furnace control at OAO Magnitogorskii Metallurgicheskii Kombinat is demonstrated. © 2013 Allerton Press, Inc

Magneto-Acoustic Waves of Small Amplitude in Optically Thin Quasi-Isentropic Plasmas

The evolution of quasi-isentropic magnetohydrodynamic waves of small but finite amplitude in an optically thin plasma is analyzed. The plasma is assumed to be initially homogeneous, in thermal equilibrium and with a straight and homogeneous magnetic field frozen in. Depending on the particular form of the heating/cooling function, the plasma may act as a dissipative or active medium for magnetoacoustic waves, while Alfven waves are not directly affected. An evolutionary equation for fast and slow magnetoacoustic waves in the single wave limit, has been derived and solved, allowing us to analyse the wave modification by competition of weakly nonlinear and quasi-isentropic effects. It was shown that the sign of the quasi-isentropic term determines the scenario of the evolution, either dissipative or active. In the dissipative case, when the plasma is first order isentropically stable the magnetoacoustic waves are damped and the time for shock wave formation is delayed. However, in the active case when the plasma is isentropically overstable, the wave amplitude grows, the strength of the shock increases and the breaking time decreases. The magnitude of the above effects depends upon the angle between the wave vector and the magnetic field. For hot (T > 10^4 K) atomic plasmas with solar abundances either in the interstellar medium or in the solar atmosphere, as well as for the cold (T < 10^3 K) ISM molecular gas, the range of temperature where the plasma is isentropically unstable and the corresponding time and length-scale for wave breaking have been found.Comment: 14 pages, 10 figures. To appear in ApJ January 200

Fine structure of near-band-edge photoluminescence in He+-irradiated GaN grown on SiC

The effect of He ion implantation on the optical properties of epitaxial GaN-on-SiC was studied. We observed that He + irradiation increases the relative intensity of the “blue emission” and resistivity of GaN films and decreases the intensity of the near-band-edge photoluminescence. Because the intensity of the main peak is drastically decreased, the fine structure of the near-band-edge photoluminescence in GaN after He + irradiation was observed. From a comparison of observed sharp lines with photoluminescence peaks of GaNdoped with oxygen, we conclude that oxygen can produce a complex, which is characterized by a strong localization of free carriers and a large lattice distortion. The zero-phonon line of this defect has energy close to the band-gap energy of GaN

Modern methodology and computer technologies for creating software of model systems supporting decision-making in metallurgy (On the example of blast-furnace production)

Experience shows that the creation and successful introduction of modern automated information systems into the practice of metallurgical enterprises largely depends on the technologies used to develop and to select the tools for their software implementation. The article briefly reflects the main technologies and software used to create software for information modeling systems to solve technological problems in metallurgy. The basis is the use of a flexible development methodology – the Agile method, which focuses on the use of iterative develop- ment, the dynamic formation of user requirements, and the provision of their implementation as a result of constant interaction within working groups consisting of specialists of various profiles (users, analysts, programmers, testers). Iteration is a relatively short development time (usually a month), after which the users are provided with the next tested version of the software product with new functional properties. The list of realized functional properties is priority for users and is formed from the general list of requirements before the beginning of each iteration. During each iteration, the following processes are sequentially performed: checking the correctness of the calculation algorithm (if necessary, entering new calculated indicators); functional modeling of the system; improvement of the structure of the subsystem; conceptual modeling of the database, generation of the database model; loading test data into the database; creation of functional diagrams of mathematical library; implementation of client software subsystems; testing and debugging of software; development of reference documentation. Managing individual tasks and monitoring the progress of their implementation in the course of collective software development are carried out on the basis of the Atlassian JIRA system. Code storage and versioning of software are performed in a remote repository on the Atlasian Bitbucket platform. The use of modern technologies, tools and techniques for developing software products makes it possible to create functional, reliable, easy-to-use, followed, integrated systems with minimal risks and at acceptable times. © 2017, National University of Science and Technology MISIS. All rights reserved