ОБОСНОВАНИЕ МЕТОДОВ РАСЧЕТОВ ПАРАМЕТРОВ ГИДРОТРАНСПОРТА ВыСОКОКОНЦЕНТРИРОВАННыХ ГИДРОСМЕСЕЙ

Днепропетровская область – крупный промышленный регион, в котором сосредоточены предприятия металлургической, химической и машинострои-тельной отраслей промышленности, расположенный на пересечении водных путей, железнодорожных и автомобильных магистралей, направленных к ме-сторождениям каменных углей и железной руды. Металлургические заводы, коксохимические комбинаты и тепловые электростанции являются крупней-шими потребителями воды, основного экологического ресурса планеты, а также основными источниками загрязнения водного бассейна региона. Несмотря на использование на таких предприятиях замкнутых циклов водоснабжения, про-блема аккумулирования жидких отходов остается для них актуальной и острой. Особенно актуальным это является для горно-обогатительных комбинатов (ГОК) Кривбасса, большая часть которых заканчивает эксплуатацию хранилищ отходов, построенных в 60-70 годы прошлого столетия. Дальнейшее развитие региона во многом определяется промышленным потенциалом этих предпри-ятий, поскольку они, с одной стороны, являются потребителями угля, железной руды и прочих ресурсов, чем обеспечивают работоспособность отечественных предприятий, а с другой стороны, выпускают продукцию, потребителями кото-рой являются многие предприятия страны

Argumentationsanalyse von Kommentaren in einem Forum der BBC zur Unabhängigkeit des Kosovo

Die vorliegende Arbeit geht hervor aus dem Hauptseminar „Argumentationstheorie“, das im Wintersemester 2008/09 am Institut für Linguistik der Universität zu Köln unter der Leitung von PD Dr. Leila Behrens abgehalten wurde. Ziel dieses Seminars war es, ausgehend von traditionellen Begriffen der Rhetorik, Dialektik und Logik, in die Terminologie sowie in zentrale Modelle der zeitgenössischen Argumentationsforschung einzuführen. Die dabei erworbenen Kenntnisse sollen im Folgenden bei der Analyse von Beiträgen eines Diskussionsforums im Internet angewendet werden. Hierbei handelt es sich um ein sogenanntes „newsforum“ der BBC mit dem Titel „Have Your Say“ (BBC 2008), in dem aktuelle Themen und Nachrichten von Internetnutzern weltweit diskutiert werden können. Im untersuchten Fall behandeln wir die Frage, wie mit der Unabhängigkeitserklärung des Kosovo vom 17. Februar 2008 umzugehen sei: „Should the world recognise an independent Kosovo?“ […]. Zu dieser Fragestellung wurden insgesamt 3195 Beiträge im Forum veröffentlicht, von denen hier 780 ausgewertet werden. Diese folgen chronologisch aufeinander und umfassen den Zeitraum zwischen 7:49 Uhr (mittlere Greenwich-Zeit) und 14:26 Uhr des 17. Februar 2008

Spin dynamics of the planar kagome lattice ferromagnet with four-site ring exchange processes

By means of quantum Monte Carlo simulations, combined with a stochastic analytic continuation, we examine the spin dynamics of the spin-1/2 planar (XY) ferromagnet on the kagome lattice with additional four-site ring exchange terms. Such exchange processes were previously considered to lead into an extended $Z_2$ quantum spin liquid phase beyond a quantum critical point from the XY-ferromagnet. We examine the dynamical spin structure factor in the non-magnetic regime and probe for signatures of spin fractionalization. Furthermore, we contrast our findings and the corresponding energy scales of the excitation gaps in the ring exchange model to those emerging in a related Balents-Fisher-Girvin model with a $Z_2$ quantum spin liquid phase, and monitor the softening of the magnon mode upon approaching the quantum critical point from the XY-ferromagnetic regime.Comment: 5 pages, 5 figure

Nonordinary criticality at the edges of planar spin-1 Heisenberg antiferromagnets

Dangling edge spins of dimerized two-dimensional spin-1 Heisenberg antiferromagnets are shown to exhibit nonordinary quantum critical correlations, akin to the scaling behavior observed in recently explored spin-1/2 systems. Based on large-scale quantum Monte Carlo simulations, we observe remarkable similarities between these two cases, and also examine the crossover to the fundamentally distinct behavior in the one-dimensional limit of strongly coupled edge spins. We complement our numerical analysis by a cluster mean-field theory that encompasses the qualitatively similar behavior for the spin-1 and the spin-1/2 case, and its dependence on the spatial edge spin configuration in a generic way.Comment: 11 pages, 12 figure

Anisotropic XY antiferromagnets in a field

Classical anisotropic XY antiferromagnets in a field on square and simple cubic lattices are studied using mainly Monte Carlo simulations. While in two dimensions the ordered antiferromagnetic and spin--flop phases are observed to be separated by a narrow disordered phase, a line of direct transitions of first order between the two phases and a bicritical point are found in three dimensions. Results are compared to previous findings.Comment: 6 pages, 7 figure

Performance management

Title from coverSIGLEAvailable from British Library Document Supply Centre- DSC:4362. 6165(748) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Finite-size effects in Luther-Emery phases of Holstein and Hubbard models

The one-dimensional Holstein model and its generalizations have been studied extensively to understand the effects of electron-phonon interaction. The half-filled case is of particular interest, as it describes a transition from a metallic phase with a spin gap due to attractive backscattering to a Peierls insulator with charge-density-wave (CDW) order. Our quantum Monte Carlo results support the existence of a metallic phase with dominant power-law charge correlations, as described by the Luther-Emery fixed point. We demonstrate that for Holstein and also for purely fermionic models the spin gap significantly complicates finite-size numerical studies, and explains inconsistent previous results for Luttinger parameters and phase boundaries. On the other hand, no such complications arise in spinless models. The correct low-energy theory of the spinful Holstein model is argued to be that of singlet bipolarons with a repulsive, mutual interaction. This picture naturally explains the existence of a metallic phase, but also implies that gapless Luttinger liquid theory is not applicable.Comment: 17 pages, 18 figures, final versio

Comment on "The role of electron-electron interactions in two-dimensional Dirac fermions"

Tang et al. [Science 361, 570 (2018)] report on the properties of Dirac fermions with both on-site and Coulomb interactions. The substantial decrease up to ~40% of the Fermi velocity of Dirac fermions with on-site interaction is inconsistent with the numerical data near the Gross-Neveu quantum critical point. This results from an inappropriate finite-size extrapolation.Comment: Submitted: October 24, 2018, Accepted: November 4, 201