714 research outputs found

    Invasions of Alien Plant Species in the South Urals: Current State of the Problem

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    Aim: assessment of the current state of the introduction of alien species into the territory of the Bashkortostan Republic. Objectives: identification of aggressive neophyte invasion centers, mapping their distribution in the region, the description of communities containing such neophytes, assessment of the population, and reproductive characteristics of these species and the development of recommendations about controlling invasive processes. The characteristics of the adventive component of the flora of the Bashkortostan Republic (457 species) are provided in the article. The most aggressive invasive species (Ambrosia trifida, A. psylostachya, Cyclachaena xanthiifolia, Hordeum jubatum, Bidens frondosa, etc.), which take root in sinantropic and natural communities in proportions of between 18% and 99%, are considered. The biomass of invasive plants is up to 6 kg/m2 , while the density is over 1,000 escapes per 1 m2 . Data on the ecology, phytocenotic confinedness and distribution of these species are presented. Ecological harm is connected with the replacement of local plants, the contamination of lands and the allergenicity of the pollen from a number of invasive species. Keywords: South Urals, Bashkortostan Republic, alien species, invasions, controlling number

    Numerical investigation of large elastoplastic strains of three-dimensional bodies

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    A method of stress-strain analysis of elastoplastic bodies with large displacements, rotations, and finite strains is developed. The incremental loading technique is used within the framework of the arbitrary Lagrangian-Eulerian formulation. Constitutive equations are derived which relate the Jaumann derivative of the Cauchy-Euler stress tensor and the strain rate. The spatial discretization is based on the FEM and multilinear three-dimensional isoparametric approximation. An algorithm of stress-strain analysis of elastic, hyperelastic, and perfectly plastic bodies is given. Numerical examples demonstrate the capabilities of the method and its software implementation

    Numerical investigation of large elastoplastic strains of three-dimensional bodies

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    A method of stress-strain analysis of elastoplastic bodies with large displacements, rotations, and finite strains is developed. The incremental loading technique is used within the framework of the arbitrary Lagrangian-Eulerian formulation. Constitutive equations are derived which relate the Jaumann derivative of the Cauchy-Euler stress tensor and the strain rate. The spatial discretization is based on the FEM and multilinear three-dimensional isoparametric approximation. An algorithm of stress-strain analysis of elastic, hyperelastic, and perfectly plastic bodies is given. Numerical examples demonstrate the capabilities of the method and its software implementation. ©2005 Springer Science+Business Media, Inc

    Postbuckling elastoplastic state analysis of three-dimensional bodies taking into account finite strains

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    A technique for analyzing the stress strain state of elastoplastic bodies taking into account large displacements, rotations, finite strains, and buckling is presented. The step-by-step loading method with formulation of the resolvent variation equation in the current configuration is used. The governing equations for elastoplastic bodies that connect the Jaumann derivative of the Cauchy-Euler stress tensor with the velocity strain are applied. The spatial discretization is based on the finite element method (FEM) in the framework of the polylinear three-dimensional isoparameteric approximation. The numerical solutions of the problems are given. © Allerton Press, Inc. 2008

    Measurement of tensor polarization of deuterons from He-3 -\u3e d plus p breakup at internal momenta up to 0.4 GeV/c

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    The tensor polarization (rho 20) of deuterons emitted in the p(He-3, d)X reaction at 0 degrees in the lab. system was measured at the Saturne National Laboratory in Sac lay, using the SPES-4 spectrometer with the HYPOM polarimeter in the area of its focal plane. The momentum of the detected deuterons was kept fixed at 3.77 GeV/c, while the momentum of the He-3 beam was varied from 4.60 to 5.66 GeV/c, thus providing a range of internal momenta k of the deuteron inside the He-3 from 0 up to 0.4 GeV/c. The obtained data are compared with the theoretical predictions

    Tensor analyzing power Ayy in deuteron inclusive breakup at large Pt and spin structure of deuteron at short internucleonic distances

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    The Ayy data for deuteron inclusive breakup off hydrogen and carbon at a deuteron momentum of 9.0 GeV/c and large Pt of emitted protons are presented. The large values of Ayy independent of the target mass reflect the sensitivity of the data to the deuteron spin structure. The data obtained at fixed xx and plotted versus Pt clearly demonstrate the dependence of the deuteron spin structure at short internucleonic distances on two variables. The data are compared with the calculations using Paris, CD-Bonn and Karmanov's deuteron wave functions.Comment: 4 pages, 2 figures, talk given at the SPIN2004 Conf., 10-16 Oct. 2004, Triest, Ital

    The history of the forming and the features of the soil, lithological and geomorphological structure of the Jizzakh steppe as the basais for its natural zoning

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    The paper provides initial materials characterizing the complicated history of formation, natural soils and lithological-geomorphological conditions of the Jizzakh steppe before the beginning of reclamation development. It is shown that on the basis of soil-lithological and geomorphological zoning, the Jizzakh steppe is divided into a number of natural regions belonging to different levels (altitude levels) of the piedmont plain. In total, 22 districts have been identified within the Jizzakh steppe, including the foothill margins. On the piedmont plain itself, the regions are combined into two high-altitude levels: the upper step and the lower step or blanket zone. These two levels differ sharply in terms of drainage conditions and soil salinity. The upper level, covering the upper and middle parts of the alluvial fan, the high interconal Zaamin-Sanzar plain and the Lomakino plateau, is characterized by a weak manifestation of salinity due to relatively good drainage, except for the sloping depressions of the Lomakino plateau. In contrast to the upper level, the lower level, located in the blanket zone of the piedmont plain, is characterized by active natural salinization because of the poor drainage. The saline sediments of the Zaamin cone delta are characterized by the greatest thickness. To a lesser extent, the rocks of the Sanzar cone delta, which are drained by deep gullies, are salinized. The Khavast sloping plain is characterized by a strongly saline upper two-meter layer, with salt and gypsum content decreasing with depth. Thus, it is shown that high salinity and gypsum bearing rocks, as well as high groundwater salinity of the cone delta zone are the source of modern salt accumulation in soils of foothill Golodnostepskaya plain, as well as in soils of the cone delta zone of Djizak steppe

    Tensor Ayy and vector Ay analyzing powers in the H(d,d')X and ^{12}C(d,d')X reactons at initial deuteron momenta of 9 GeV/c in the region of baryonic resonances excitation

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    The angular dependence of the tensor Ayy and vector Ay analyzing powers in the inelastic scattering of deuterons with a momentum of 9.0 GeV/c on hydrogen and carbon have been measured. The range of measurements corresponds to the baryonic resonance excitation with masses 2.2--2.6 GeV/c^2. The Ayy data being in good agreement with the previous results demonstrate an approximate tt scaling up to -1.5 (GeV/c)^2. The large values of A_y show a significant role of the spin-dependent part of the elementary amplitude of the NN->NN* reaction. The results of the experiment are compared with model predictions of the plane-wave impulse approximation.Comment: 7 pages, 7 figures. submitted to Yad.Fi

    Structural phase transitions in the kagome lattice based materials Cs2-xRbxSnCu3F12 (x = 0, 0.5, 1.0, 1.5)

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    The solid solution Cs2-xRbxSnCu3F12 (x = 0, 0.5, 1.0, 1.5) has been investigated crystallographically between 100 and 300 K using synchrotron X-ray powder diffraction and, in the case of x = 0, neutron powder diffraction.Comment: 14 pages, 9 figure
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