Logical-mathematical Evaluation Model of Blast-furnace Melting Operation

The logical-mathematical evaluation model of blast-furnace melting operation is represented. The model provides an opportunity to evaluate the normal operation mode of blast furnace and further deviations from this mode such as overdeveloped gas flows (peripheral and central), violation of thermal melting conditions (hot and cold course of melt), violation of smooth descent of burned materials in the furnace (tight furnace operation, higher and lower suspension of burden). The functional capabilities of developed software are represented. Keywords: blast-furnace production, information logical system, software development, blast-furnace melting operation diagnostic

Ultrafast electronic response of Ag(111) and Cu(111) surfaces: From early excitonic transients to saturated image potential

Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).We investigate the evolution of attosecond to femtosecond screening and emergent potentials that govern the dynamics and energetics of electrons and holes excited in the various stages of multiphoton photoemission processes and control the photoelectron yield in recently reported experiments [X. Cui, C. Wang, A. Argondizzo, S. Garrett-Roe, B. Gumhalter, and H. Petek, Nat. Phys. 10, 505 (2014)1745-247310.1038/nphys2981]. The study is focused on the dynamical screening of holes created in preexistent quasi-two-dimensional Shockley state bands on Ag(111) and Cu(111) surfaces and of electrons excited to the intermediate and emerging screened states. Using the formalism of self-consistent electronic response, we analyze first the effects of screening on the dynamics of photoexcited electrons and holes and then of the Coulomb correlated photoexcited pair. Special attention is paid to the correlated primary electron-hole states, which commence as transient surface excitons and develop in the course of screening into uncorrelated electrons and holes propagating in the image potential and surface state bands, respectively. The obtained results enable to establish a consistent picture of transient electron dynamics at Ag(111) and Cu(111) surfaces that are becoming accessible by the time-, energy-, and momentum-resolved pump-probe multiphoton photoelectron spectroscopies.V.M.S. acknowledges partial support from the Basque Departamento de Educacion, UPV/EHU (Grant No. IT-756-13) and the Spanish Ministry od Economy and Competitiveness MINECO (Grant No. FIS2013-48286-C2-1-P). N.D. acknowledges the support of the Unity Through Knowledge Fund (UKF B1). H.P. was supported by the Division of Chemical Sciences, Geosciences and Biosciences, Office of Basic Energy Sciences of the U.S. Department of Energy through Grant DE-FG02-09ER 16056.Peer Reviewe

New variants of variable neighbourhood search for 0-1 mixed integer programming and clustering

Many real-world optimisation problems are discrete in nature. Although recent rapid developments in computer technologies are steadily increasing the speed of computations, the size of an instance of a hard discrete optimisation problem solvable in prescribed time does not increase linearly with the computer speed. This calls for the development of new solution methodologies for solving larger instances in shorter time. Furthermore, large instances of discrete optimisation problems are normally impossible to solve to optimality within a reasonable computational time/space and can only be tackled with a heuristic approach. In this thesis the development of so called matheuristics, the heuristics which are based on the mathematical formulation of the problem, is studied and employed within the variable neighbourhood search framework. Some new variants of the variable neighbourhood searchmetaheuristic itself are suggested, which naturally emerge from exploiting the information from the mathematical programming formulation of the problem. However, those variants may also be applied to problems described by the combinatorial formulation. A unifying perspective on modern advances in local search-based metaheuristics, a so called hyper-reactive approach, is also proposed. Two NP-hard discrete optimisation problems are considered: 0-1 mixed integer programming and clustering with application to colour image quantisation. Several new heuristics for 0-1 mixed integer programming problem are developed, based on the principle of variable neighbourhood search. One set of proposed heuristics consists of improvement heuristics, which attempt to find high-quality near-optimal solutions starting from a given feasible solution. Another set consists of constructive heuristics, which attempt to find initial feasible solutions for 0-1 mixed integer programs. Finally, some variable neighbourhood search based clustering techniques are applied for solving the colour image quantisation problem. All new methods presented are compared to other algorithms recommended in literature and a comprehensive performance analysis is provided. Computational results show that the methods proposed either outperform the existing state-of-the-art methods for the problems observed, or provide comparable results. The theory and algorithms presented in this thesis indicate that hybridisation of the CPLEX MIP solver and the VNS metaheuristic can be very effective for solving large instances of the 0-1 mixed integer programming problem. More generally, the results presented in this thesis suggest that hybridisation of exact (commercial) integer programming solvers and some metaheuristic methods is of high interest and such combinations deserve further practical and theoretical investigation. Results also show that VNS can be successfully applied to solving a colour image quantisation problem.EThOS - Electronic Theses Online ServiceMathematical Institute, Serbian Academy of Sciences and ArtsGBUnited Kingdo

The mechanism of caesium intercalation of graphene

Properties of many layered materials, including copper- and iron-based superconductors, topological insulators, graphite and epitaxial graphene can be manipulated by inclusion of different atomic and molecular species between the layers via a process known as intercalation. For example, intercalation in graphite can lead to superconductivity and is crucial in the working cycle of modern batteries and supercapacitors. Intercalation involves complex diffusion processes along and across the layers, but the microscopic mechanisms and dynamics of these processes are not well understood. Here we report on a novel mechanism for intercalation and entrapment of alkali-atoms under epitaxial graphene. We find that the intercalation is adjusted by the van der Waals interaction, with the dynamics governed by defects anchored to graphene wrinkles. Our findings are relevant for the future design and application of graphene-based nano-structures. Similar mechanisms can also play a role for intercalation of layered materials.Comment: 8 pages, 7 figures in published form, supplementary information availabl

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

Antioksidativna aktivnost etanolnih ekstrakata Solanum Retroflexum

In this paper the antioxidant activity of ethanolic extracts from Solanum retroflexum Dun fruits were investigated. The extracts were obtained by classical technique and by Soxhlet extraction. In order to investigate the possibilities of future utilization of Solanum retroflexum fruits, the antioxidant activity, by FRAP and DPPH method was determined. Results showed the extract obtained by 75% ethanol and classic extraction during 45 minutes at 60°C, had the highest antioxidant activity, both for DPPH and FRAP method (EC50 was 60,67 μg/mL and 1,55 μmol Fe2+/mg, respectively). There was good correlation of results for antioxidant activity obtained by both methods and for all analyzed extracts.Rad se bavi ispitivanjem antioksidativne aktivnosti etanolnih ekstrakata ploda biljke Solanum retroflexum Dun. Ekstrakti su dobijeni tehnikama klasične i Soxhlet extrakcije. Potencijalna antioksidativna aktivnost je ispitana FRAP i DPPH metodama. Rezultati su pokazali da ekstrakt dobijen klasičnom ekstrakcijom sa 75% rastvorom etanola na 60°C i za vreme 45 minuta, ima najveću antioksidativnu aktivnost (EC50 = 60,67 μg/ml, 1,55 μmol Fe2+/mg), kao i da postoji dobra korelacija rezultata dobijenih obema metodama u slučaju svih analiziranih ekstrakata