75 research outputs found

    Comparative Analysis of Surface Plants of the Ground Sealing Composition in the Implementation of Construction Works

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    Processes of layer-by-layer consolidation of soil at construction of the bulk engineering constructions built by method of continuous consolidation are considered. Ways of realization of these processes on the basis of two technological schemes - elliptic and shuttle are shown. The assessment of key parameters is made during the operation of units on the classical elliptic scheme of continuous consolidation of soil and on the elliptic scheme with use of a ring method of a turn of the unit when in the course of construction of a road bed automobile and the railroads the movement of the condensing unit is made from roadsides to an axis. It is shown that working platform* more effective andleast critical to topographical and geometrical parameters, the shuttle scheme of consolidation at which the condensing cars make the back and forth motions accompanied with lateral shift on an adjacent working strip after achievement of the demanded density on the previous strip is. The analsis of the major factors proving application of this or that technological scheme of soil consolidation is made. Operating conditions of units depending on type of the used condensing unit and the accepted production technology of works on elliptic and shuttle schemes which realization allows to reach the greatest production effect are studie

    Vortex Polarity Switching in Magnets with Surface Anisotropy

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    Vortex core reversal in magnetic particle is essentially influenced by a surface anisotropy. Under the action of a perpendicular static magnetic field the vortex core undergoes a shape deformationof pillow- or barrel-shaped type, depending on the type of the surface anisotropy. This deformation plays a key point in the switching mechanism: We predict that the vortex polarity switching is accompanied (i) by a linear singularity in case of Heisenberg magnet with bulk anisotropy only and (ii) by a point singularities in case of surface anisotropy or exchange anisotropy. We study in details the switching process using spin-lattice simulations and propose a simple analytical description using a wired core model, which provides an adequate description of the Bloch point statics, its dynamics and the Bloch point mediated switching process. Our analytical predictions are confirmed by spin-lattice simulations for Heisenberg magnet and micromagnetic simulations for nanomagnet with account of a dipolar interaction.Comment: 17 pages, 15 figure

    The motion of the 2D hydrodynamic Chaplygin sleigh in the presence of circulation

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    We consider the motion of a planar rigid body in a potential flow with circulation and subject to a certain nonholonomic constraint. This model is related to the design of underwater vehicles. The equations of motion admit a reduction to a 2-dimensional nonlinear system, which is integrated explicitly. We show that the reduced system comprises both asymptotic and periodic dynamics separated by a critical value of the energy, and give a complete classification of types of the motion. Then we describe the whole variety of the trajectories of the body on the plane.Comment: 25 pages, 7 figures. This article uses some introductory material from arXiv:1109.321

    The Study of Bacterial Leaching of Synthetic Valleriite-Containing Materials

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    Проведены поисковые эксперименты по бактериальному кондиционированию синтетического валлериита в аэробных и анаэробных условиях. В ходе аэробного процесса происходит окислительное выщелачивание валлериита с образованием соединений железа (+3) и меди (+2). В анаэробных условиях поверхность валлериита, по данным рентгенофотоэлектронной спектроскопии, частично окисляется, особенно за счет сульфидной серы, связанной с железом (+3), но медь остается в степени окисления +1 в составе валлериита и частично сульфидов меди. Установленные закономерности окисления валлериита необходимо учитывать при разработке технологий обогащения и химико-металлургической переработке валлериитсодержащих рудUnder aerobic and anaerobic conditions, a series of preliminary experiments on bacterial leaching of synthetic valleriites were performed. Under aerobic conditions, an oxidative leaching of iron (+3) and copper (+2) species was found. Under anaerobic conditions, surface of valleeriite was revealed by XPS analysis to oxidize, at least, partially, especially, due to sulfide sulfur. However, copper has kept its oxidative state (+1) in both initial material and, to some extent, in newly formed copper (+1) sulfide. The characteristics established in the present work are necessary to take into account when developing beneficiation technologies and hydrometallurgical processing of valleriite-bearing ore

    Investigation of the splitting of quark and gluon jets

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    The splitting processes in identified quark and gluon jets are investigated using longitudinal and transverse observables. The jets are selected from symmetric three-jet events measured in Z decays with the Delphi detector in 1991-1994. Gluon jets are identified using heavy quark anti-tagging. Scaling violations in identified gluon jets are observed for the first time. The scale energy dependence of the gluon fragmentation function is found to be about two times larger than for the corresponding quark jets, consistent with the QCD expectation TeX . The primary splitting of gluons and quarks into subjets agrees with fragmentation models and, for specific regions of the jet resolution TeX , with NLLA calculations. The maximum of the ratio of the primary subjet splittings in quark and gluon jets is TeX . Due to non-perturbative effects, the data are below the expectation at small TeX . The transition from the perturbative to the non-perturbative domain appears at smaller TeX for quark jets than for gluon jets. Combined with the observed behaviour of the higher rank splittings, this explains the relatively small multiplicity ratio between gluon and quark jets

    Measurement of the Quark and Gluon Fragmentation Functions in Z0Z^0 Hadronic Decays

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    The fragmentation functions and multiplicities in bbb\overline{b} and light quark events are compared. The measured transverse and longitudinal components of the fragmentation function allow the gluon fragmentation function to be evaluated

    First Measurement of the Strange Quark Asymmetry at the Z0Z^{0} Peak

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    Measurement of inclusive π0\pi^{0} production in hadronic Z0Z^{0} decays

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    An analysis is presented of inclusive \pi^0 production in Z^0 decays measured with the DELPHI detector. At low energies, \pi^0 decays are reconstructed by \linebreak using pairs of converted photons and combinations of converted photons and photons reconstructed in the barrel electromagnetic calorimeter (HPC). At high energies (up to x_p = 2 \cdot p_{\pi}/\sqrt{s} = 0.75) the excellent granularity of the HPC is exploited to search for two-photon substructures in single showers. The inclusive differential cross section is measured as a function of energy for {q\overline q} and {b \bar b} events. The number of \pi^0's per hadronic Z^0 event is N(\pi^0)/ Z_{had}^0 = 9.2 \pm 0.2 \mbox{(stat)} \pm 1.0 \mbox{(syst)} and for {b \bar b}~events the number of \pi^0's is {\mathrm N(\pi^0)/ b \overline b} = 10.1 \pm 0.4 \mbox{(stat)} \pm 1.1 \mbox{(syst)} . The ratio of the number of \pi^0's in b \overline b events to hadronic Z^0 events is less affected by the systematic errors and is found to be 1.09 \pm 0.05 \pm 0.01. The measured \pi^0 cross sections are compared with the predictions of different parton shower models. For hadronic events, the peak position in the \mathrm \xi_p = \ln(1/x_p) distribution is \xi_p^{\star} = 3.90^{+0.24}_{-0.14}. The average number of \pi^0's from the decay of primary \mathrm B hadrons is found to be {\mathrm N} (B \rightarrow \pi^0 \, X)/\mbox{B hadron} = 2.78 \pm 0.15 \mbox{(stat)} \pm 0.60 \mbox{(syst)}

    Measurement of the Bd0^{0}_{d} oscillation frequency using kaons, leptons and jet charge

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    A measurement of the mass difference, \Delta m_d, between the two physical \mbox{B}^0_d states has been obtained from the analysis of the impact parameter distribution of a lepton emitted at large transverse momentum (p_t) relative to the jet axis and from the analysis of the flight distance distribution of secondary vertices tagged by either a high p_t lepton or an identified kaon. In the opposite hemisphere of the event, the charge of the initial quark has been evaluated using a high p_t lepton, a charged kaon or the mean jet charge. With 1.7 million hadronic Z^0 decays recorded by DELPHI between 1991 and 1993, \Delta m_d is found to be: \Delta m_d = 0.531^{+0.050}_{-0.046} ~(stat.) \pm 0.078 ~(syst.) ~ {\mathrm{ps}}^{-1} \,

    Measurements of the leptonic branching fractions of the τ\tau

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    Data collected with the DELPHI detector from 1993 to 1995 combined with previous DELPHI results for data from 1991 and 1992 yield the branching fractions B({\tau \rightarrow \mbox{\rm e} \nu \bar{\nu}}) = (17.877 \pm 0.109_{stat} \pm 0.110_{sys} )\% and B(τμννˉ)=(17.325±0.095stat±0.077sys)%B({\tau \rightarrow \mu \nu \bar{\nu}}) = (17.325 \pm 0.095_{stat} \pm 0.077_{sys} )\%
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