19,594 research outputs found

    A Force-Balanced Control Volume Finite Element Method for Multi-Phase Porous Media Flow Modelling

    Get PDF
    Dr D. Pavlidis would like to acknowledge the support from the following research grants: Innovate UK ‘Octopus’, EPSRC ‘Reactor Core-Structure Re-location Modelling for Severe Nuclear Accidents’) and Horizon 2020 ‘In-Vessel Melt Retention’. Funding for Dr P. Salinas from ExxonMobil is gratefully acknowledged. Dr Z. Xie is supported by EPSRC ‘Multi-Scale Exploration of Multi-phase Physics in Flows’. Part funding for Prof Jackson under the TOTAL Chairs programme at Imperial College is also acknowledged. The authors would also like to acknowledge Mr Y. Debbabi for supplying analytic solutions.Peer reviewedPublisher PD

    The complex Sine-Gordon equation as a symmetry flow of the AKNS Hierarchy

    Full text link
    It is shown how the complex sine-Gordon equation arises as a symmetry flow of the AKNS hierarchy. The AKNS hierarchy is extended by the ``negative'' symmetry flows forming the Borel loop algebra. The complex sine-Gordon and the vector Nonlinear Schrodinger equations appear as lowest negative and second positive flows within the extended hierarchy. This is fully analogous to the well-known connection between the sine-Gordon and mKdV equations within the extended mKdV hierarchy. A general formalism for a Toda-like symmetry occupying the ``negative'' sector of sl(N) constrained KP hierarchy and giving rise to the negative Borel sl(N) loop algebra is indicated.Comment: 8 pages, LaTeX, typos corrected, references update

    Hanbury Brown Twiss effect for ultracold quantum gases

    Full text link
    We have studied 2-body correlations of atoms in an expanding cloud above and below the Bose-Einstein condensation threshold. The observed correlation function for a thermal cloud shows a bunching behavior, while the correlation is flat for a coherent sample. These quantum correlations are the atomic analogue of the Hanbury Brown Twiss effect. We observe the effect in three dimensions and study its dependence on cloud size.Comment: Figure 1 availabl

    Ionization rates in a Bose-Einstein condensate of metastable Helium

    Full text link
    We have studied ionizing collisions in a BEC of He*. Measurements of the ion production rate combined with measurements of the density and number of atoms for the same sample allow us to estimate both the 2 and 3-body contributions to this rate. A comparison with the decay of the number of condensed atoms in our magnetic trap, in the presence of an rf-shield, indicates that ionizing collisions are largely or wholly responsible for the loss. Quantum depletion makes a substantial correction to the 3-body rate constant.Comment: 4 pages, 3 figure

    Nonrelativistic Limit of the Scalar Chern-Simons Theory and the Aharonov-Bohm Scattering

    Get PDF
    We study the nonrelativistic limit of the quantum theory of a Chern-Simons field minimally coupled to a scalar field with quartic self-interaction. The renormalization of the relativistic model, in the Coulomb gauge, is discussed. We employ a procedure to calculate scattering amplitudes for low momenta that generates their p/m|p|/m expansion and separates the contributions coming from high and low energy intermediary states. The two body scattering amplitude is calculated up to order p2/m2p^2/m^2. It is shown that the existence of a critical value of the self-interaction parameter for which the 2-particle scattering amplitude reduces to the Aharonov-Bohm one is a strictly nonrelativistic feature. The subdominant terms correspond to relativistic corrections to the Aharonov-Bohm scattering. A nonrelativistic reduction scheme and an effective nonrelativistic Lagrangian to account for the relativistic corrections are proposed.Comment: 22 pages, 8 figures, revtex, to be published in Int. J. Mod. Phys.

    Interação nitrogênio, fósforo, potássio na cultura da mandioca no Norte de Mato Grosso.

    Get PDF
    Na Região Norte do Estado de Mato Grosso, foram testadas doses de adubação fosfatada (0, 40, 80 e 120 kg de P2O5/ha) em interação com nitrogênio (o e 40 kg de N/ha) e potássio (0 e 40 kg de K2O/ha) para a cultura da mandioca, em dois ciclos de cultivo, de novembro/81 a marco/83, com a cultivar "Cuiabana", e de outubro/82 a fevereiro/84, com a cultivar "Juriti". Determinou-se a produção de folhas, hastes, cepa, raiz, número de plantas e porcentagem de amido. Não foram observados diferenças significativas entre tratamento para nenhuma das variáveis nos dois ciclos.bitstream/item/81260/1/interacao-nitrogenio-Laercio-Duarte-Boletim-Pesquisa-9-1992.pdfMemória
    corecore