102 research outputs found

    Application of synchrotron radiation to study the surface atomic structure of 2D materials

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    In this paper, the current state of X-ray photoelectron diffraction and holography methods are considered. A brief overview of surface research methods is given. The photoelectron diffraction method is attractive for use because of its sensitivity to the chemical environment, as well as its large depth of analysis (units of nanometers). The paper presents the application of methods for studying the atomic structure of bismuth chalcogenides Bi2X3 (X: Se,Te). The results of the holography were verified by theoretical modeling of diffraction patterns using the EDAC algorithm. © 2020 American Institute of Physics Inc. All rights reserved.The reported study was funded by RFBR, project number 19-29-12061 and was carried out within the state assignment of Ministry of Science and Higher Education of the Russian Federation (theme “Spin” No. АААА-А18-118020290104-2). L.V.Yashina acknowledges the support of her experimental work by RSF, grant 19-42-06303. We thank HZB for the allocation of synchrotron radiation beamtime

    Galactic Rotation Parameters from Data on Open Star Clusters

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    Currently available data on the field of velocities Vr, Vl, Vb for open star clusters are used to perform a kinematic analysis of various samples that differ by heliocentric distance, age, and membership in individual structures (the Orion, Carina--Sagittarius, and Perseus arms). Based on 375 clusters located within 5 kpc of the Sun with ages up to 1 Gyr, we have determined the Galactic rotation parameters Wo =-26.0+-0.3 km/s/kpc, W'o = 4.18+-0.17 km/s/kpc^2, W''o=-0.45+-0.06 km/s/kpc^3, the system contraction parameter K = -2.4+-0.1 km/s/kpc, and the parameters of the kinematic center Ro =7.4+-0.3 kpc and lo = 0+-1 degrees. The Galactocentric distance Ro in the model used has been found to depend significantly on the sample age. Thus, for example, it is 9.5+-0.7 kpc and 5.6+-0.3 kpc for the samples of young (50 Myr) clusters, respectively. Our study of the kinematics of young open star clusters in various spiral arms has shown that the kinematic parameters are similar to the parameters obtained from the entire sample for the Carina-Sagittarius and Perseus arms and differ significantly from them for the Orion arm. The contraction effect is shown to be typical of star clusters with various ages. It is most pronounced for clusters with a mean age of 100 Myr, with the contraction velocity being Kr = -4.3+-1.0 km/s.Comment: 14 pages, 4 figures, 2 table

    Asymmetrical current generator operating modes in battery charging

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    This paper presents the investigation of the different operating modes of the asymmetrical quasi-sinusoidal output current inductive-switch generator. The purpose of investigation is to find the most effective operation mode where an acceptable output current quality is combined with relatively small dynamic losses in switches. Depending on the algorithm of the generator switches, there are four operating modes. The calculations describing the generator operating principle were obtained for each operating mode

    IMPLEMENTATION OF THE EDAC ALGORITHM FOR CALCULATING PHOTOELECTRON DIFFRACTION IN MATLAB

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    This paper discusses the implementation of the EDAC algorithm in the MATLAB devel-opment environment. This allows you to use the features of MatLab, as well as further sharing in the open source format.Работа выполнена при поддержке РФФИ № 19-29-12061 и проводилось в рамках государственного задания Министерства науки и высшего образования РФ (тема «Спин» № AAAA-A18-118020290104-2). Л.В. Яшина благодарит РНФ за поддержку ее экспериментальной работы, грант 19-42-06303

    Kinematic Peculiarities of Gould Belt Stars

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    We analyzed the space velocities of Gould Belt stars younger than 125 Myr located at heliocentric distances <650 pc. We determined the rotation and expansion parameters of the Gould Belt by assuming the existence of a single kinematic center whose direction was found to be the following: l=128l_\circ=128^\circ and R=150R_\circ=150 pc. The linear velocities reach their maximum at a distance of 300\approx300 pc from the center and are -6 km s1^{-1} for the rotation (whose direction coincides with the Galactic rotation) and +4 km s1^{-1} for the expansion. The stellar rotation model used here is shown to give a more faithful description of the observed velocity field than the linear model based on the Oort constants AGA_G and BGB_G. We present evidence that the young clusters β\beta Pic, Tuc/HorA, and TWA belong to the Gould Belt structure.Comment: 17 pages, 5 figure
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