The modern technology of iron and steel production and possible ways of their development

В изменяющейся мировой обстановке на рынке сырых материалов для черной металлургии разрабатывается ряд новых технологий по производству чугуна и стали, альтернативных существующим технологиям, которые способны обеспечить экономически устойчивую работу металлургических компаний. В дополнении к этому фокусируется внимание на экономии энергии и снижении выбросов парниковых газов в целях решения важнейших вопросов охраны окружающей среды. Изменение состояния окружающей среды ставит новые проблемы перед металлургической промышленностью, потребляющей значительные энергетические и топливные ресурсы. Отрасль вынуждена сосредоточить свое внимание на сокращении всех видов энергии, что приведет и к снижению выброса парниковых газов. Разработка альтернативных технологических процессов производства чугуна и стали способна обеспечить металлургическим компаниям экономически выгодную и устойчивую работу в производстве стали. Для оценки воздействий деятельности металлургических компаний на окружающую среду Инженерно-консалтинговой компанией ХАТЧ (НАТСH, Сanada) были разработаны новые методики моделирования, позволяющие квалифицированно и качественно оценивать риски в потреблении энергии и выбросах СО2 в металлургической промышленности. Методика для анализа выбросов углеродсодержащих парниковых газов названа G-CAP ™ (Зеленый Дом — Борьба с загрязнением воздуха углекислым газом), а для анализа энергоэффективности — En-MAPTM (Планирование действий при управлении энергией). Оценка существующего положения в большинстве интегрированных заводов показала, что они располагают возможностями по экономии энергии и борьбы с загрязнением атмосферы парниковыми газами, лучшие из этих заводов исчерпали эти возможности даже при высоких ценах на квоты выбросов СО2. В этом контексте важно оценить те важные особенности альтернативных технологий получения чугуна и стали, которые разработаны к настоящему времени. Эта статья содержит сравнительную оценку энергоэффективности и выбросов ПГ для некоторых выбранных альтернативных технологий производства чугуна и стали, которые рассматриваются для их реализации. Для этого применены методики G-CAP ™ и G-CAP ™ , элементы которых были разработаны в компании HATCH с основной целью количественной и квалификационной оценки потенциала экономии энергии и сокращения выбросов СО2 в металлургической промышленностиIn the changing global market scenario for raw materials for the steel industry, a number of novel iron and steelmaking process technologies are being developed to provide the steel companies with economically-sustainable alternatives for iron and steel-making. In addition, the steel industry is also focusing on reduction of energy consumption as well as green-house gas (GHG) emissions to address the crucial subject of climate change. Climate change is presenting new risks to the highly energy and carbon-intensive, iron and steel industry. The industry needs to focus on reduction of energy consumption as GHG emissions to address climate change. Development of alternate iron and steelmaking process technologies can provide steel companies with economically-sustainable alternatives for steel production. For managing climate change risks, novel modelling tools have been developed by Hatch to quantify and qualify potential energy savings and CO2 abatement within the iron and steel industry. The tool developed for abatement of greenhouse gas carbon is called G-CAPTM (Green-House Gas Carbon Abatement Process) while that developed for improving energy efficiency is called En-MAPTM (Energy Management Action Planning). Evaluation of existing operations have shown that most integrated plants have GHG and energy abatement opportunities; on the other hand, the best-in-class plants may not have a lot of low-risk abatement opportunities left, even at high CO2 price. In this context, it is important to assess these critical issues for the alternate iron and steelmaking technologies that have been developed. This paper presents a comparative evaluation of energy-efficiency and GHG emissions for some selected iron- and steelmaking technologies that are being considered for implementation. In this work, Hatch’s G-CAP™ and En-MAP™ tools that were developed with the main objective of quantifying and qualifying the potential energy savings and CO2 abatement within the iron and steel industry, were employed in the evaluation conducted

Majority Rule Dynamics in Finite Dimensions

We investigate the long-time behavior of a majority rule opinion dynamics model in finite spatial dimensions. Each site of the system is endowed with a two-state spin variable that evolves by majority rule. In a single update event, a group of spins with a fixed (odd) size is specified and all members of the group adopt the local majority state. Repeated application of this update step leads to a coarsening mosaic of spin domains and ultimate consensus in a finite system. The approach to consensus is governed by two disparate time scales, with the longer time scale arising from realizations in which spins organize into coherent single-opinion bands. The consequences of this geometrical organization on the long-time kinetics are explored.Comment: 8 pages, 2-column revtex format, 11 figures. Version 2: minor changes in response to referee comments and typos corrected; final version for PR

Translation of non-capped mRNAs in a eukaryotic cell-free system: acceleration of initiation rate in the course of polysome formation

Real-time monitoring of the translation of non-capped luciferase mRNA in a wheat germ cell-free system has been performed by continuous in situ measurement of the luminescence increase in the translation mixture. The phenomenon of acceleration of translation has been revealed. It has been shown that the acceleration is accompanied by the loading of translating polysomes with additional ribosomes, and thus is caused mainly by a rise in the initiation rate, rather than the stimulation of elongation or the involvement of additional mRNA molecules in translation. The acceleration requires a sufficient concentration of mRNA and depends on the sequence of the 5′ untranslated region (UTR). It can be abolished by the addition of excess cap analog (m7GpppGm). As the acceleration does not depend on the preliminary translation of other mRNAs in the same extract, the conclusion has been made that the effect is not due to activation of the ribosome population or other components of the system during translation, but rather it is the consequence of intra-polysomal events. The acceleration observed is discussed in terms of the model of two overlapping initiation pathways in eukaryotic polysomes: translation of non-capped mRNAs starts with eIF4F-independent initiation at 5′ UTR, and after the formation of sufficiently loaded polysomes, they rearrange in such a way that a mechanism of re-initiation of terminating ribosomes switches on. The eIF4F-mediated circularization of polysomes may be considered as a possible event that leads to the re-initiation switch and the resultant acceleration effect

Comparison of voter and Glauber ordering dynamics on networks

We study numerically the ordering process of two very simple dynamical models for a two-state variable on several topologies with increasing levels of heterogeneity in the degree distribution. We find that the zero-temperature Glauber dynamics for the Ising model may get trapped in sets of partially ordered metastable states even for finite system size, and this becomes more probable as the size increases. Voter dynamics instead always converges to full order on finite networks, even if this does not occur via coherent growth of domains. The time needed for order to be reached diverges with the system size. In both cases the ordering process is rather insensitive to the variation of the degreee distribution from sharply peaked to scale-free.Comment: 12 pages, 12 figure

Stochastic kinetics of ribosomes: single motor properties and collective behavior

Synthesis of protein molecules in a cell are carried out by ribosomes. A ribosome can be regarded as a molecular motor which utilizes the input chemical energy to move on a messenger RNA (mRNA) track that also serves as a template for the polymerization of the corresponding protein. The forward movement, however, is characterized by an alternating sequence of translocation and pause. Using a quantitative model, which captures the mechanochemical cycle of an individual ribosome, we derive an {\it exact} analytical expression for the distribution of its dwell times at the successive positions on the mRNA track. Inverse of the average dwell time satisfies a ``Michaelis-Menten-like'' equation and is consistent with the general formula for the average velocity of a molecular motor with an unbranched mechano-chemical cycle. Extending this formula appropriately, we also derive the exact force-velocity relation for a ribosome. Often many ribosomes simultaneously move on the same mRNA track, while each synthesizes a copy of the same protein. We extend the model of a single ribosome by incorporating steric exclusion of different individuals on the same track. We draw the phase diagram of this model of ribosome traffic in 3-dimensional spaces spanned by experimentally controllable parameters. We suggest new experimental tests of our theoretical predictions.Comment: Final published versio

Majority versus minority dynamics: Phase transition in an interacting two-state spin system

We introduce a simple model of opinion dynamics in which binary-state agents evolve due to the influence of agents in a local neighborhood. In a single update step, a fixed-size group is defined and all agents in the group adopt the state of the local majority with probability p or that of the local minority with probability 1-p. For group size G=3, there is a phase transition at p_c=2/3 in all spatial dimensions. For p>p_c, the global majority quickly predominates, while for p<p_c, the system is driven to a mixed state in which the densities of agents in each state are equal. For p=p_c, the average magnetization (the difference in the density of agents in the two states) is conserved and the system obeys classical voter model dynamics. In one dimension and within a Kirkwood decoupling scheme, the final magnetization in a finite-length system has a non-trivial dependence on the initial magnetization for all p.ne.p_c, in agreement with numerical results. At p_c, the exact 2-spin correlation functions decay algebraically toward the value 1 and the system coarsens as in the classical voter model.Comment: 11 pages, 3 figures, revtex4 2-column format; minor revisions for publication in PR

Phase separation of the Potts model in que square lattice

When the two dimensional q-color Potts model in the square lattice is quenched at zero temperature with Glauber dynamics, the energy decreases in time following an Allen-Cahn power law, and the system converges to a phase with energy higher than the ground state energy after an arbitrary large time when q>4. At low but finite temperature, it cesses to obey the power-law regime and orders after a very long time, which increases with q, and before which it performs a domain growth process which tends to be slower as q increases. We briefly present and comment numerical results on the ordering at nonzero temperature.Comment: 3 pages, 1 figure, proceedings of the "International Workshop on Complex sytems", June 2006 in Santander (Spain

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