The research of dynamics of mechanical system with variable parameters

Free vibrations of the single-mass system with variable parameters that characterize inertia, friction, rigidity are considered. For an exact analytical solution the method of constant coefficients under derivatives with a new variable is propose

Investigation of longitudinal oscillations warp in the process of changing parameters system

The paper studies the longitudinal vibrations of warp (rope) in the process of change “warp-trawl” system parameters. The analytical solution of this task is giving. In particular, the dependences are determined longitudinal force component in vaybere. Also studied in rough seas impact on the dynamics of the system “warp-trawl”

On homogeneous statistical distributions exoplanets for their dynamic parameters

Correct distributions of extrasolar systems for their orbital parameters (semi-major axes, period, eccentricity) and physical characteristics (mass, spectral type of parent star) are received. Orbital resonances in extrasolar systems are considered. It is shown, that the account of more thin effects, including with use of wavelet methods, in obviously incorrectly reduced distributions it is not justified, to what the homogeneous statistical distributions for dynamic parameters of exoplanets, received in the present work, testify.Comment: 9 pages, 15 figures; International Conference "100 years since Tunguska phenomenon: Past, present and future", (June 26-28, 2008. Russia, Moscow), Lomonosov readings 2009 (Moscow State University

A comparative study of density functional and density functional tight binding calculations of defects in graphene

The density functional tight binding approach (DFTB) is well adapted for the study of point and line defects in graphene based systems. After briefly reviewing the use of DFTB in this area, we present a comparative study of defect structures, energies and dynamics between DFTB results obtained using the dftb+ code, and density functional results using the localised Gaussian orbital code, AIMPRO. DFTB accurately reproduces structures and energies for a range of point defect structures such as vacancies and Stone-Wales defects in graphene, as well as various unfunctionalised and hydroxylated graphene sheet edges. Migration barriers for the vacancy and Stone-Wales defect formation barriers are accurately reproduced using a nudged elastic band approach. Finally we explore the potential for dynamic defect simulations using DFTB, taking as an example electron irradiation damage in graphene

Graphene edge structures: Folding, scrolling, tubing, rippling and twisting

Conventional three-dimensional crystal lattices are terminated by surfaces, which can demonstrate complex rebonding and rehybridisation, localised strain and dislocation formation. Two dimensional crystal lattices, of which graphene is the archetype, are terminated by lines. The additional available dimension at such interfaces opens up a range of new topological interface possibilities. We show that graphene sheet edges can adopt a range of topological distortions depending on their nature. Rehybridisation, local bond reordering, chemical functionalisation with bulky, charged, or multi-functional groups can lead to edge buckling to relieve strain, folding, rolling and even tube formation. We discuss the topological possibilities at a 2D graphene edge, and under what circumstances we expect different edge topologies to occur. Density functional calculations are used to explore in more depth different graphene edge types.Comment: Additional figure in published versio

History of formation and development of liability for damage caused by sources of extreme danger in Vietnam: Issues of legal influence

This article analyzes the influence of Western legal ideology and socialist law on the formation and development of liability for damage caused by sources of extreme danger in the law of Vietnam. The authors have examined all the important legal documents that are associated with the issue of liability for damage caused by sources of extreme danger. The research materials are also based on the works of Western and Eastern authors writing about Vietnam during this historical period. To achieve this goal, the authors used the following methods: comparative legal, analysis, synthesis and historical method. The conclusions of the study showed that: under the influence of French legal ideology during the period of French colonization, liability for harm caused by sources of increased danger first appeared in the law of Vietnam. For the first time in Vietnamese civil law, the term "source of extreme danger" is used with the adoption of the Circular of the Supreme People's Court No. 173-TANDTS dated March 23, 1972. From 1986 to the present, this liability has been created and developed under the influence of old Soviet law and current Russian law. &nbsp

STRUCTURE AND MAGNETIC PROPERTIES OF Mn–Zn-FERRITES

Synthesis conditions, structure and magnetic properties of Mn-Zn-ferrites prepared by spray pyrolysis of solutions of manganese, zinc and iron nitrates have been considered. The applied technique provides low-temperature (650 °C) obtaining highly dispersed (7-8 nm) powder of Mn0.5Zn0.5Fe2O4 ferrite with a narrow size distribution. Synthesis of Mn0.5Zn0.5Fe2O4 at low temperature avoids MnII → MnIII oxidation reaction that influences the ferrite properties. IR data collected from the ferrite samples obtained both in air and in N2 ambient indicate their high structural and concentration homogeneity. Magnetic measurements confirm single-phase structure of the Mn0.5Zn0.5Fe2O4 powders and give no evidence of the presence of individual iron oxide phases. Curie temperature (375-380 K) is consistent with the theoretically calculated value for Mn1-xZnxFe2O4 (x = 0.5) (Tc = 365÷385 K). Parameters of Moessbauer spectra of the ferrites are typical of FeIII state in oxide solid solutions with a considerable ionicity contribution in Fe-O bonds (δ = 0.33÷0.34 mm/s). FeII state was not revealed by Moessbauer spectroscopy that indicates the absence of FeIII → FeII reduction accompanying the MnII → MnIII oxidation process