32,529 research outputs found
Effect of incommensurate disorder on the resonant tunneling through Majorana bound states on the topological superconductor chains
We study the transport through the Kitaev's chain with incommensurate
potentials coupled to two normal leads by the numerical operator method. We
find a quantized linear conductance of , which is independent to the
disorder strength and the gate voltage in a wide range, signaling the Majorana
bound states. While the incommensurate disorder suppresses the current at
finite voltage bias, and then narrows the linear response regime of the
curve which exhibits two plateaus corresponding to the superconducting gap and
the band edge respectively. The linear conductance abruptly drops to zero as
the disorder strength reaches the critical value with the
p-wave pairing amplitude, corresponding to the transition from the topological
superconducting phase to the Anderson localized phase. Changing the gate
voltage will also cause an abrupt drop of the linear conductance by driving the
chain into the topologically trivial superconducting phase, whose curve
exhibits an exponential shape.Comment: 9 pages, 7 figure
An aerodynamic analysis of a novel small wind turbine based on impulse turbine principles
This document is the Accepted Manuscript of the following article: Pei Ying, Yong Kang Chen, and Yi Geng Xu, ‘An aerodynamic analysis of a novel small wind turbine based on impulse turbine principles’, Renewable Energy, Vol. 75: 37-43, March 2015, DOI: https://doi.org/10.1016/j.renene.2014.09.035, made available under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License CC BY NC-ND 4.0 http://creativecommons.org/licenses/by-nc-nd/4.0/The paper presents both a numerical and an experimental approach to study the air flow characteristics of a novel small wind turbine and to predict its performance. The turbine model was generated based on impulse turbine principles in order to be employed in an omni-flow wind energy system in urban areas. The results have shown that the maximum flow velocity behind the stator can be increased by 20% because of a nozzle cascade from the stator geometry. It was also observed that a wind turbine with a 0.3 m rotor diameter achieved the maximum power coefficient of 0.17 at the tip speed ratio of 0.6 under the wind velocity of 8.2 m/s. It was also found that the power coefficient was linked to the hub-to-tip ratio and reached its maximum value when the hub-to-tip ratio was 0.45. It is evident that this new wind turbine has the potential for low working noise and good starting feature compared with a conventional horizontal axis wind turbine.Peer reviewedFinal Accepted Versio
S-Duality for D3-Brane in NS-NS and R-R Backgrounds
We construct the low-energy effective field theory for a D3-brane in constant
R-R 2-form potential background as the S-dual theory of a D3-brane in NS-NS
B-field background. Despite the non-Abelian algebra of the noncommutative U(1)
gauge symmetry, the electromagnetic duality transformation can be carried out
to all orders, and the dual Lagrangian is given in a compact form. The gauge
algebra is found to be a mixture of a deformed area-preserving diffeomorphism
and the usual U(1) gauge symmetry.Comment: 29 pages, minor change
Extension and parameterization of high-order density dependence in Skyrme forces
The three-body force is indispensable in nuclear energy density functionals
which leads to a density dependent two-body term in the Hartree-Fock approach.
Usually a single factional power of density dependency has been adopted. We
consider the possibility of an additional higher-order density dependence in
extended Skyrme forces. As a result, new extended Skyrme parametertizations
based on the SLy4 force are obtained and the improvements in descriptions of
global nuclei have been demonstrated. The higher-order term can also
substantially affect nuclear properties in the high density region in general
ways.Comment: 6 pages, 5 figure
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