94,001 research outputs found

    The tensor structure on the representation category of the Wp\mathcal{W}_p triplet algebra

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    We study the braided monoidal structure that the fusion product induces on the abelian category Wp\mathcal{W}_p-mod, the category of representations of the triplet WW-algebra Wp\mathcal{W}_p. The Wp\mathcal{W}_p-algebras are a family of vertex operator algebras that form the simplest known examples of symmetry algebras of logarithmic conformal field theories. We formalise the methods for computing fusion products, developed by Nahm, Gaberdiel and Kausch, that are widely used in the physics literature and illustrate a systematic approach to calculating fusion products in non-semi-simple representation categories. We apply these methods to the braided monoidal structure of Wp\mathcal{W}_p-mod, previously constructed by Huang, Lepowsky and Zhang, to prove that this braided monoidal structure is rigid. The rigidity of Wp\mathcal{W}_p-mod allows us to prove explicit formulae for the fusion product on the set of all simple and all projective Wp\mathcal{W}_p-modules, which were first conjectured by Fuchs, Hwang, Semikhatov and Tipunin; and Gaberdiel and Runkel.Comment: 58 pages; edit: added references and revisions according to referee reports. Version to appear on J. Phys.

    The effects of protected beams and their connections on the fire resistance of composite buildings

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    According to full-scale fire tests, it is noticed that tensile membrane action within the concrete floor slabs plays an important role in affecting the fire resistance of composite buildings. It is well known that the development of tensile membrane actions relies on the vertical support along the edges of the slab panel. However, there is at present a lack of research into the influence of vertical supports on the tensile membrane actions of the floor slabs. In this paper, the performances of a generic three dimensional 45m x 45m composite floor subjected to ISO834 Fire and Natural Fire are investigated. Different vertical support conditions and three steel meshes are applied in order to assess the impact of vertical supports on tensile membrane action of floor slabs. Unlike other existing large scale modelling which assumes the connections behave as pinned or rigid for simplicity, two robust 2-node connection element models developed by the authors are used to model the behaviour of end-plate and partial end-plate connections of composite structures under fire conditions. The impact of connections on the 3D behaviour of composite floor is taken into consideration. The load-transfer mechanisms of composite floor when connections fail due to axial tension, vertical shear and bending are investigated. Based on the results obtained, some design recommendations are proposed to enhance the fire resistance of composite buildings

    Open-closed field algebras

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    We introduce the notions of open-closed field algebra and open-closed field algebra over a vertex operator algebra V. In the case that V satisfies certain finiteness and reductivity conditions, we show that an open-closed field algebra over V canonically gives an algebra over a \C-extension of the Swiss-cheese partial operad. We also give a tensor categorical formulation and categorical constructions of open-closed field algebras over V.Comment: 55 pages, largely revised, an old subsection is deleted, a few references are adde

    N K and Delta K states in the chiral SU(3) quark model

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    The isospin I=0 and I=1 kaon-nucleon SS, PP, DD, FF wave phase shifts are studied in the chiral SU(3) quark model by solving the resonating group method (RGM) equation. The calculated phase shifts for different partial waves are in agreement with the experimental data. Furthermore, the structures of the ΔK\Delta K states with L=0, I=1 and I=2 are investigated. We find that the interaction between Δ\Delta and KK in the case of L=0, I=1 is attractive, which is not like the situation of the NKNK system, where the SS-wave interactions between NN and KK for both I=0 and I=1 are repulsive. Our numerical results also show that when the model parameters are taken to be the same as in our previous NNNN and YNYN scattering calculations, the ΔK\Delta K state with L=0 and I=1 is a weakly bound state with about 2 MeV binding energy, while the one with I=2 is unbound in the present one-channel calculation.Comment: 14 pages, 6 figures. PRC70,064004(2004

    Understanding Internal Capital Markets and Corporate Policies

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    This study looks inside a large retail-banking group to understand how corporate politics affect internal capital allocation. The group consists of a headquarters organization and about 150 member banks which own the headquarters. Our data is from the firm’s managerial accounting system and covers all cash flows, internal capital transfers, and investments at the local member bank level. We first show that a member bank’s investment (net loan growth) is generally not fully independent from its own cash flow (net deposit growth). Then we show that such constraints are not apparent at more influential member banks, where influence is measured by the divergence of voting rights from ownership rights. The more influential banks are allocated more funds from the headquarters, but also show more restraints in investments when experiencing large deposit inflows. Influence matters more among member banks requiring more information exchanges with the headquarters as a result of more volatile funding requests. Influence also matters more for small business loans, which contain more soft information, than for standardized residential mortgage loans. These results suggest that corporate politics can be used to address allocation inefficiencies resulting from information asymmetries between the headquarters and divisions (member banks in our case).internal capital markets;capital markets;retail banking;corporate politics

    Microstructure control during twin roll casting of an AZ31 magnesium alloy

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    The existing twin roll casting technique for magnesium alloys suffers heterogeneity in both microstructure and chemistry and downstream processing is required to improve the strip quality, resulting in cost rise. In the present work, twin roll casting was carried out using an AZ31 magnesium alloy, with the application of intensive shearing melt conditioning prior to casting. The effect of process parameters such as pouring temperature and casting speed on microstructure control during casting and subsequent downstream processing was studied. Experimental results showed that the melt conditioning treatment allowed the production of AZ31 strips with uniform and refined microstructure free of centreline segregations. It was also shown that an optimized combination of pouring temperature and casting speed, in conjunction with a strip thickness control operation, resulted in uniformly distributed stored energies due to enhanced plastic deformation, which promoted recrystallization during casting and subsequent heat treatment. Strips prepared by twin roll casting and homogenization developed similar microstructural features to those prepared by twin roll casting followed by lengthy downstream processing by homogenization, hot rolling and annealing and displayed a weaker basal texture, exhibiting a potentially better formability.The EPSRC (UK

    Kaon-nucleon interaction in the extended chiral SU(3) quark model

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    The chiral SU(3) quark model is extended to include the coupling between the quark and vector chiral fields. The one-gluon exchange (OGE) which dominantly governs the short-range quark-quark interaction in the original chiral SU(3) quark model is now nearly replaced by the vector-meson exchange. Using this model, the isospin I=0 and I=1 kaon-nucleon S, P, D, F wave phase shifts are dynamically studied by solving the resonating group method (RGM) equation. Similar to those given by the original chiral SU(3) quark model, the calculated results for many partial waves are consistent with the experiment, while there is no improvement in this new approach for the P_{13} and D_{15} channels, of which the theoretical phase shifts are too much repulsive and attractive respectively when the laboratory momentum of the kaon meson is greater than 300 MeV.Comment: 19 pages, 16 figures. Accepted by Phys. Rev.
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