421 research outputs found

    Large Scale Structures a Gradient Lines: the case of the Trkal Flow

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    A specific asymptotic expansion at large Reynolds numbers (R)for the long wavelength perturbation of a non stationary anisotropic helical solution of the force less Navier-Stokes equations (Trkal solutions) is effectively constructed of the Beltrami type terms through multi scaling analysis. The asymptotic procedure is proved to be valid for one specific value of the scaling parameter,namely for the square root of the Reynolds number (R).As a result large scale structures arise as gradient lines of the energy determined by the initial conditions for two anisotropic Beltrami flows of the same helicity.The same intitial conditions determine the boundaries of the vortex-velocity tubes, containing both streamlines and vortex linesComment: 27 pages, 2 figure

    Topological current of point defects and its bifurcation

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    From the topological properties of a three dimensional vector order parameter, the topological current of point defects is obtained. One shows that the charge of point defects is determined by Hopf indices and Brouwer degrees. The evolution of point defects is also studied. One concludes that there exist crucial cases of branch processes in the evolution of point defects when the Jacobian D(ϕx)=0D(\frac \phi x)=0.Comment: revtex,14 pages,no figur

    Kallemoeie - 50 jaar geschiedenis

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    Studying one of the problems of wave filtration

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    Motions of particles through a permeable barrier are studied from the standpoint of Schrodinger wave dynamics. We consider time evolution of a substance concentration spot in the vicinity of one or two potential barriers. To solve the problem we developed a computer technology for integration of the non-stationary Schrödinger equation. The technology is based on symbol mapping and the matrix exponential method which was applied earlier to solve the classical heat equation. The developed theory is relevant to development of nanotechnology, in particular, to studies on permeability of nanoporous membranes

    Penetration of particles through multi-barrier systems

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    The paper gives a theoretical justification for the effect of increasing permeability of ultra-thin membranes by altering their internal material structure, namely through the process of creating one or two energy voids within the permeable layer. An effective computing technology for solving the stationary Schrödinger equation is also described

    Influence of solar activity on hydrological processes

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    International audienceThe relationship between solar activity and the water volumes of lakes is searched here by means of correlational and spectral analysis methods. The level of two lakes, Pátzcuaro in México and Tchudskoye in Russia, together with solar activity indexes are used for the analysis. It is found that the source of the oscillation mechanism of the level of those lakes is the solar activity cycle through its influence on the magnetosphere and the terrestrial atmosphere. The present study allows for the development of long-period prognostic of water volumes of big lakes

    Numerical simulation of oil pool boundary evolution

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    The study of spatial distribution of hydrocarbon resources and forecasting their geographical location is of great importance for the most complete recovery of hydrocarbons from deposits. The present study gives new mathematical results in the theory of stratified fluid flow in a porous medium. This paper analyzes the evolution of oil pool boundary basing on vortex numerical model for movement of the boundary separating fluids of different densities. It presents the investigation of how the location of light fluid regarding the heavier fluid influences on the changes in the boundary between two media in case of various shifting of the well

    Direct mass measurements of 19B, 22C, 29F, 31Ne, 34Na and other light exotic nuclei

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    We report on direct time-of-flight based mass measurements of 16 light neutron-rich nuclei. These include the first determination of the masses of the Borromean drip-line nuclei 19^{19}B, 22^{22}C and 29^{29}F as well as that of 34^{34}Na. In addition, the most precise determinations to date for 23^{23}N and 31^{31}Ne are reported. Coupled with recent interaction cross-section measurements, the present results support the occurrence of a two-neutron halo in 22^{22}C, with a dominant ν2s1/22\nu2s_{1/2}^2 configuration, and a single-neutron halo in 31^{31}Ne with the valence neutron occupying predominantly the 2p3/2p_{3/2} orbital. Despite a very low two-neutron separation energy the development of a halo in 19^{19}B is hindered by the 1d5/22d_{5/2}^2 character of the valence neutrons.Comment: 5 page
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