24,552 research outputs found

    Improving Resource Efficiency with Partial Resource Muting for Future Wireless Networks

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    We propose novel resource allocation algorithms that have the objective of finding a good tradeoff between resource reuse and interference avoidance in wireless networks. To this end, we first study properties of functions that relate the resource budget available to network elements to the optimal utility and to the optimal resource efficiency obtained by solving max-min utility optimization problems. From the asymptotic behavior of these functions, we obtain a transition point that indicates whether a network is operating in an efficient noise-limited regime or in an inefficient interference-limited regime for a given resource budget. For networks operating in the inefficient regime, we propose a novel partial resource muting scheme to improve the efficiency of the resource utilization. The framework is very general. It can be applied not only to the downlink of 4G networks, but also to 5G networks equipped with flexible duplex mechanisms. Numerical results show significant performance gains of the proposed scheme compared to the solution to the max-min utility optimization problem with full frequency reuse.Comment: 8 pages, 9 figures, to appear in WiMob 201

    Assessing Ageing Condition of Mineral Oil-Paper Insulation by Polarization/Depolarization Current

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    Accurately assessing the ageing status of oil-paper insulation in transformer is essential and important. Polarization and Depolarization Current (PDC) technique is effective in assessing the condition of oil-paper insulation system. Though the PDC behaviour of mineral oil-paper insulation has been widely investigated, there is no report about how to make the quantitative analysis of mineral oil-paper insulation ageing condition by PDC. The PDC characteristics of mineral oil-paper insulation samples were investigated over the ageing period at 110°C. A new method for assessing the ageing condition of mineral oil-paper insulation by calculating the depolarization charge quantity was proposed. Results show that the depolarization charge quantity of mineral oil-paper insulation sample is very sensitive to its ageing condition. The stable depolarization charge quantity could be used to predict the ageing condition of mineral oil-paper insulation

    A (p,q) Deformation of the Universal Enveloping Superalgebra U(osp(2/2))

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    We investigate a two parameter quantum deformation of the universal enveloping orthosymplectic superalgebra U(osp(2/2)) by extending the Faddeev-Reshetikhin-Takhtajan formalism to the supersymetric case. It is shown that Up,q(osp(2/2))U_{p,q}(osp(2/2)) possesses a non-commutative, non-cocommutative Hopf algebra structure. All the results are expressed in the standard form using quantum Chevalley basis.Comment: 8 pages; IC/93/41

    Gravitational Thermodynamics of Space-time Foam in One-loop Approximation

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    We show from one-loop quantum gravity and statistical thermodynamics that the thermodynamics of quantum foam in flat space-time and Schwarzschild space-time is exactly the same as that of Hawking-Unruh radiation in thermal equilibrium. This means we show unambiguously that Hawking-Unruh thermal radiation should contain thermal gravitons or the contribution of quantum space-time foam. As a by-product, we give also the quantum gravity correction in one-loop approximation to the classical black hole thermodynamics.Comment: 7 pages, revte

    The decay and collisions of dark solitons in superfluid Fermi gases

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    We study soliton collisions and the decay of solitons into sound in superfluid Fermi gases across the Bose-Einstein condensate to Bardeen-Cooper-Schrieffer (BEC-BCS) crossover by performing numerical simulations of the time-dependent Bogoliubov-de Gennes equations. This decay process occurs when the solitons are accelerated to the bulk pair-breaking speed by an external potential. A similar decay process may occur when solitons are accelerated by an inelastic collision with another soliton. We find that soliton collisions become increasingly inelastic as we move from the BEC to BCS regimes, and the excess energy is converted into sound. We interpret this effect as being due to evolution of Andreev bound states localized within the soliton.Comment: 9 pages, 5 figure

    Plant regeneration system from cotyledons-derived calluses cultures of Stylosanthes guianensis cv. ‘Reyan 2’

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    The objective of this study was to successfully establish plant regeneration system with cotyledons of Stylosanthes guianensis Sw. cv. ‘Reyan 2’ as explants. In this study, the following results were obtained; (1) the highest rates of callus induction on medium MS with 3.0 mg L-1 2, 4-D with cotyledons as explants were 74%. The above medium of formulation was adopted for subculture; (2) the highest rates of callus differentiation medium MS with 3.0 mg L-1 6-BA with cotyledons as explants was 66%; (3) the optimum medium of shoot growth was MS medium plus 1.0 mg L-1 6-BA, 0.5 mg L-1 NAA and 0.4 mg L-1 GA; (4) the rooting rate was 60% on optimum rooting medium with 0.2 mg L-1 NAA; (5) the survival rate of plant transplanting was 70% after transferred to pots with garden soil. In conclusion, the efficient plant regeneration system developed here will be helpful for rapid micropropagation and further genetic improvement in S. guianensis Sw. cv. ‘Reyan 2’.Key words: Stylosanthes guianensis Sw. cv. Reyan 2, callus, cotyledons, plant regeneration
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