Single-turn Coils for Magnetic Pulse Welding of High-strength Steel Parts

Magnetic pulse welding provides high quality joining of fuel pin cladding for fast nuclear reactors. The tool coil there operates under the most stressful conditions: 40 T magnetic fields with tens of microseconds duration. This requires minimal coil inductance and affects the capabilities and lifetime of the coils. Two approaches are being practiced to enhance the coil durability: material research and construction optimization. The first approach considers the use of high strength steels or composite materials for the coil working area. The present work is aimed to realize the second approach – the use of multi position coils in order to maximize the number of parts welded in one coil. Experiments and finite element modeling were carried out for two designs of two- and four-position single-turn coils, which were made to process several workpieces in one current pulse. The main parameters measured and calculated were the magnetic field between the coil and the workpiece, and the ratio of its amplitude to the discharge current, Bm/Im. The currents flowing through the coils were about 700 kA, which correspond to the magnetic fields of 40–45 T. The FEM modeling revealed a 17–19% drop of the magnetic induction near the insulated slit, which, however, did not prevent the helium-tight joining of the tubes to the end plugs

Structure of the Optimal Management System for Raw Materials, Fuel and Energy Resources in Blast-furnace Production

The structure of optimization model of optimal management of raw materials, fuel and energy resources in the blast-furnace shop of iron and steel works is represented. The following blocks are taken as system basis: (1) calculation of the set of parameters that characterize the thermal, gas-dynamic, slag and blasting modes for every blast furnaces of the shop during the base period; (2) calculation of linearized model coefficients (constants of transferring via different exposure pathways) individually for every blast furnace as well as properties of iron ore raw materials, fluxing additions, blasting parameters, parameters of fuel-enriched blast influencing the technical-and-economic indices of separate furnaces performance, their thermal, gasdynamic and slag operation modes in the course of blast-furnace melting according to UrFU-MMT blast-furnace production model within the base period; (3) solution of tasks that consider the optimal allocation of raw materials, fuel and energy resources for the project period of blast furnaces operation; (4) analysis of obtained results and providing of recommendations on the optimization of blast furnaces parameters. The developed functional model of optimal distribution of raw materials, fuel and energy resources for the engineering and technology personnel of blast-furnace shop is illustrated; the main functions and interconnections between the separate functional blocks are defined. The functions of created ‘Optimal management of raw materials, fuel and energy resources in the blast-furnace production’ software that is realized in the Microsoft Visual Studio 2017 (С# programming language) programming environment in the form of web application are pointed out. The program product provides the engineering and technology personnel of blast furnace shop of iron andsteel works with the opportunity to solve the tasks of optimal distribution of fuel and energy resources (natural gas and oxygen consumption) within the group of blast furnaces in the different technological situations. Keywords: blast-furnace production, resources distribution optimization, fuel and energy resources, raw material resources, functional modeling, decision support system, software developmen

Assessing the shape of the viscoplastic iron-ore zone in a blast furnace

A mathematical model permits assessment of the position and shape of the viscoplastic iron-ore zone (cohesion zone) in a blast furnace and identification of a rational configuration for this zone on the basis of readily available information regarding the blast furnace in the baseline period. The model also permits the solution of design problems with variation in the furnace parameters. Modeling results are outlined for the baseline and design periods. © 2013 Allerton Press, Inc

New words in human mutagenesis

<p>Abstract</p> <p>Background</p> <p>The substitution rates within different nucleotide contexts are subject to varying levels of bias. The most well known example of such bias is the excess of C to T (C > T) mutations in CpG (CG) dinucleotides. The molecular mechanisms underlying this bias are important factors in human genome evolution and cancer development. The discovery of other nucleotide contexts that have profound effects on substitution rates can improve our understanding of how mutations are acquired, and why mutation hotspots exist.</p> <p>Results</p> <p>We compared rates of inherited mutations in 1-4 bp nucleotide contexts using reconstructed ancestral states of human single nucleotide polymorphisms (SNPs) from intergenic regions. Chimp and orangutan genomic sequences were used as outgroups. We uncovered 3.5 and 3.3-fold excesses of T > C mutations in the second position of ATTG and ATAG words, respectively, and a 3.4-fold excess of A > C mutations in the first position of the ACAA word.</p> <p>Conclusions</p> <p>Although all the observed biases are less pronounced than the 5.1-fold excess of C > T mutations in CG dinucleotides, the three 4 bp mutation contexts mentioned above (and their complementary contexts) are well distinguished from all other mutation contexts. This provides a challenge to discover the underlying mechanisms responsible for the observed excesses of mutations.</p

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

Cyclotron resonance of extremely conductive 2D holes in high Ge content strained heterostructures

Cyclotron resonance has been observed in steady and pulsed magnetic fields from high conductivity holes in Ge quantum wells. The resonance positions, splittings and linewidths are compared to calculations of the hole Landau levels

Optimal allocation of fuel and energy resources in the complex blast-furnace plants

The paper presents the model of optimal allocation of power resources in a blast furnace taking into account the change of smelting parameters. The optimization model allows to predict parameters of injected fuel on separate (at individual, in certain) blast furnaces in various technological situations. At problem formulation and task solution, the model considers the static characteristics describing the influence of changes of melting conditions on overall economic indicators of furnaces, the mathematical description external and internal limitations on operation of some blast furnaces and blast-furnace plant generally. Informational-modelling system optimization of allocation of natural gas in a blast-furnace plant was developed on the presented model. This model includes: input and adjustment of data; calculation module; optimization; output and the assaying of results. The results of comparative assaying of allocation of natural gas on the basis of operation data of the blast-furnace plant of OJSC “Magnitogorsk Iron and Steel Works ” are achieved. Analysis of the results shows that the optimization model of joint distribution of natural gas and oxygen allows to use effectively the available fuel and energy resources, taking account the technological limitations in the work of individual furnaces as well as a plant in general

Algorithms and software for optimal management of raw materials, fuel and energy resources in blast furnace production

The structure of optimization model of optimal management of raw materials, fuel and energy resources in the blast-furnace shop of iron and steel works is represented. The following blocks are taken as system basis: 1) calculation of the set of parameters that characterize the thermal, gas-dynamic, slag and blasting modes for every blast furnaces of the shop during the base period; 2) calculation of linearized model coefficients (constants of transferring via different exposure pathways) individually for every blast furnace as well as properties of iron ore raw materials, fluxing additions, blasting parameters, parameters of fuel-enriched blast influencing the technical-and-economic indices of separate furnaces performance, their thermal, gas-dynamic and slag operation modes in the course of blast-furnace melting according to UrFU-MMK blast-furnace production model within the base period; 3) solution of tasks that consider the optimal allocation of raw materials, fuel and energy resources for the project period of blast furnaces operation; 4) analysis of obtained results and providing of recommendations on the optimization of blast furnaces parameters. The developed functional model of optimal distribution of raw materials, fuel and energy resources for the engineering and technology personnel of blast-furnace shop is illustrated; the main functions and interconnections between the separate functional blocks are defined. The functions of created "Optimal management of raw materials, fuel and energy resources in the blast-furnace production"software that is realized in the Microsoft Visual Studio 2017 (C# programming language) programming environment in the form of web application are pointed out. The program product provides the engineering and technology personnel of blast furnace shop of iron and steel works with the opportunity to solve the tasks of optimal distribution of fuel and energy resources (natural gas and oxygen consumption) within the group of blast furnaces in the different technological situations. © Published under licence by IOP Publishing Ltd

Temperature-driven single-valley Dirac fermions in HgTe quantum wells

We report on temperature-dependent magnetospectroscopy of two HgTe/CdHgTe quantum wells below and above the critical well thickness $d_c$. Our results, obtained in magnetic fields up to 16 T and temperature range from 2 K to 150 K, clearly indicate a change of the band-gap energy with temperature. The quantum well wider than $d_c$ evidences a temperature-driven transition from topological insulator to semiconductor phases. At the critical temperature of 90 K, the merging of inter- and intra-band transitions in weak magnetic fields clearly specifies the formation of gapless state, revealing the appearance of single-valley massless Dirac fermions with velocity of $5.6\times10^5$ m$\times$s$^{-1}$. For both quantum wells, the energies extracted from experimental data are in good agreement with calculations on the basis of the 8-band Kane Hamiltonian with temperature-dependent parameters.Comment: 5 pages, 3 figures and Supplemental Materials (4 pages