10,807 research outputs found

    (Almost) Everything You Always Wanted to Know About Deterministic Control Problems in Stratified Domains

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    We revisit the pioneering work of Bressan \& Hong on deterministic control problems in stratified domains, i.e. control problems for which the dynamic and the cost may have discontinuities on submanifolds of R N . By using slightly different methods, involving more partial differential equations arguments, we (i) slightly improve the assumptions on the dynamic and the cost; (ii) obtain a comparison result for general semi-continuous sub and supersolutions (without any continuity assumptions on the value function nor on the sub/supersolutions); (iii) provide a general framework in which a stability result holds

    ESTIMATION OF INCOME DISTRIBUTION AND DETECTION OF SUBPOPULATIONS: AN EXPLANATORY MODEL

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    Inequality and polarization analyses are complementary but conceptually different. They are usually implemented independently in practic e, with different a priori assumptions and different tools. In this paper, we develop a unique method to study simultaneously these different and complementary concerns. Based on mixture models, the method we develop includes at the same time : an estimation of income distribution with no a priori assumptions - a decomposition in several homogeneous subpopulations - an explanatory model to study the structure of the income distribution.

    Power Estimation in LTE systems with the General Framework of Standard Interference Mappings

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    We devise novel techniques to obtain the downlink power inducing a given load in long-term evolution (LTE) systems, where we define load as the fraction of resource blocks in the time-frequency grid being requested by users from a given base station. These techniques are particularly important because previous studies have proved that the data rate requirement of users can be satisfied with lower transmit energy if we allow the load to increase. Those studies have also shown that obtaining the power assignment from a desired load profile can be posed as a fixed point problem involving standard interference mappings, but so far the mappings have not been obtained explicitly. One of our main contributions in this study is to close this gap. We derive an interference mapping having as its fixed point the power assignment inducing a desired load, assuming that such an assignment exists. Having this mapping in closed form, we simplify the proof of the aforementioned known results, and we also devise novel iterative algorithms for power computation that have many numerical advantages over previous methods.Comment: IEEE Global SIP 201

    Probing double parton scattering via associated open charm and bottom production in ultraperipheral pApA collisions

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    In this article, we propose a novel channel for phenomenological studies of the double-parton scattering (DPS) based upon associated production of charm ccˉc\bar{c} and bottom bbˉb\bar{b} quark pairs in well-separated rapidity intervals in ultra-peripheral high-energy proton-nucleus collisions. This process provides a direct access to the double-gluon distribution in the proton at small-xx and enables one to test the factorised DPS pocket formula. We have made the corresponding theoretical predictions for the DPS contribution to this process at typical LHC energies and beyond and we compute the energy-independent (but photon momentum fraction dependent) effective cross section.Comment: 15 pages, 7 figs., 1 table. One fig. added. Version accepted for publication at EPJ

    Prediction of pressure drop in multiphase horizontal pipe flow

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    Empirical correlations were tested against reliable two phase pipe flow data for the prediction of pressure drop. Correlations are recommended for the prediction with stratified and annular type flows. When these correlations were adapted to three phase gaswater-oil pipe flow in general they predicted for intermittent slug type flows. Momentum balance models could not be successfully adapted to the prediction of pipe three phase pressure drop

    Texture Zeros and Weak Basis Transformations

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    We investigate the physical meaning of some of the "texture zeros" which appear in most of the Ansatze on quark masses and mixings. It is shown that starting from arbitrary quark mass matrices and making a suitable weak basis transformation one can obtain some of these sets of zeros which therefore have no physical content. We then analyse the physical implications of a four-texture zero Ansatz which is in agreement with all present experimental data.Comment: 11 pages, typeset using revte

    Exclusive heavy quark-pair production in ultraperipheral collisions

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    In this article, we study the fully differential observables of exclusive production of heavy (charm and bottom) quark pairs in high-energy ultraperipheral pApA and AAAA collisions. In these processes, the nucleus AA serves as an efficient source of the photon flux, while the QCD interaction of the produced heavy-quark pair with the target (pp or AA) proceeds via an exchange of gluons in a color singlet state, described by the gluon Wigner distribution. The corresponding predictions for differential cross sections were obtained by using the dipole SS-matrix in the McLerran--Venugopalan saturation model with impact parameter dependence for the nucleus target, and its recent generalization, for the proton target. Prospects of experimental constraints on the gluon Wigner distribution in this class of reactions are discussed.Comment: 21 pages, 18 figures, improved conclusio
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