47,604 research outputs found
Tunable Fano-Kondo resonance in side-coupled double quantum dot system
We study the interference between the Fano and Kondo effects in a
side-coupled double-quantum- dot system where one of the quantum dots couples
to conduction electron bath while the other dot only side-couples to the first
dot via antiferromagnetic (AF) spin exchange coupling. We apply both the
perturbative renormalization group (RG) and numerical renormalization group
(NRG) approaches to study the effect of AF coupling on the Fano lineshape in
the conduction leads. With particle-hole symmetry, the AF exchange coupling
competes with the Kondo effect and leads to a local spin-singlet ground state
for arbitrary small coupling, so called "two-stage Kondo effect". As a result,
via NRG we find the spectral properties of the Fano lineshape in the tunneling
density of states (TDOS) of conduction electron leads shows double dip-peak
features at the energy scale around the Kondo temperature and the one much
below it, corresponding to the two-stage Kondo effect; it also shows an
universal scaling behavior at very low energies. We find the qualitative
agreement between the NRG and the perturbative RG approach. Relevance of our
work to the experiments is discussed.Comment: 7 pages, 7 figure
Quantum criticality out of equilibrium in the pseudogap Kondo model
We theoretically investigate the non-equilibrium quantum phase transition in
a generic setup: the pseudogap Kondo model where a quantum dot couples to
two-left (L) and right (R)-voltage-biased fermionic leads with power-law
density of states (DOS) with respect to their Fermi levels {\mu}_L/R,
{\rho}_c,L(R) ({\omega}) \propto |{\omega} - {\mu}_L(R) |r, and 0 < r < 1. In
equilibrium (zero bias voltage) and for 0 < r < 1/2, with increasing Kondo
correlations, in the presence of particle-hole symmetry this model exhibits a
quantum phase transition from a unscreened local moment (LM) phase to the Kondo
phase. Via a controlled frequency-dependent renormalization group (RG)
approach, we compute analytically and numerically the non-equilibrium
conductance, conduction electron T-matrix and local spin susceptibility at
finite bias voltages near criticality. The current-induced decoherence shows
distinct nonequilibrium scaling, leading to new universal non-equilibrium
quantum critical behaviors in the above observables. Relevance of our results
for the experiments is discussed.Comment: 4.1 pages, 2 figure
Extraction of nuclear matter properties from nuclear masses by a model of equation of state
The extraction of nuclear matter properties from measured nuclear masses is
investigated in the energy density functional formalism of nuclei. It is shown
that the volume energy and the nuclear incompressibility depend
essentially on , whereas the symmetry energy
and the density symmetry coefficient as well as symmetry incompressibility
depend essentially on , where
, and are the
neutron and proton chemical potentials respectively, the nuclear energy,
and the Coulomb energy. The obtained symmetry energy is ,
while other coefficients are uncertain within ranges depending on the model of
nuclear equation of state.Comment: 12 pages and 7 figure
Reliability assessment of microgrid with renewable generation and prioritized loads
With the increase in awareness about the climate change, there has been a
tremendous shift towards utilizing renewable energy sources (RES). In this
regard, smart grid technologies have been presented to facilitate higher
penetration of RES. Microgrids are the key components of the smart grids.
Microgrids allow integration of various distributed energy resources (DER) such
as the distributed generation (DGs) and energy storage systems (ESSs) into the
distribution system and hence remove or delay the need for distribution
expansion. One of the crucial requirements for utilities is to ensure that the
system reliability is maintained with the inclusion of microgrid topology.
Therefore, this paper evaluates the reliability of a microgrid containing
prioritized loads and distributed RES through a hybrid analytical-simulation
method. The stochasticity of RES introduces complexity to the reliability
evaluation. The method takes into account the variability of RES through Monte-
Carlo state sampling simulation. The results indicate the reliability
enhancement of the overall system in the presence of the microgrid topology. In
particular, the highest priority load has the largest improvement in the
reliability indices. Furthermore, sensitivity analysis is performed to
understand the effects of the failure of microgrid islanding in the case of a
fault in the upstream network
Effective nucleon-nucleon interactions and nuclear matter equation of state
Nuclear matter equations of state based on Skyrme, Myers-Swiatecki and
Tondeur interactions are written as polynomials of the cubic root of density,
with coefficients that are functions of the relative neutron excess .
In the extrapolation toward states far away from the standard one, it is shown
that the asymmetry dependence of the critical point ()
depends on the model used. However, when the equations of state are fitted to
the same standard state, the value of is almost the same in Skyrme
and in Myers-Swiatecki interactions, while is much lower in Tondeur
interaction. Furthermore, does not depend sensitively on the choice
of the parameter in Skyrme interaction.Comment: 15 pages, 9 figure
Fast Spectral Clustering Using Autoencoders and Landmarks
In this paper, we introduce an algorithm for performing spectral clustering
efficiently. Spectral clustering is a powerful clustering algorithm that
suffers from high computational complexity, due to eigen decomposition. In this
work, we first build the adjacency matrix of the corresponding graph of the
dataset. To build this matrix, we only consider a limited number of points,
called landmarks, and compute the similarity of all data points with the
landmarks. Then, we present a definition of the Laplacian matrix of the graph
that enable us to perform eigen decomposition efficiently, using a deep
autoencoder. The overall complexity of the algorithm for eigen decomposition is
, where is the number of data points and is the number of
landmarks. At last, we evaluate the performance of the algorithm in different
experiments.Comment: 8 Pages- Accepted in 14th International Conference on Image Analysis
and Recognitio
Nuclear matter properties and relativistic mean-field theory
Nuclear matter properties are calculated in the relativistic mean field
theory by using a number of different parameter sets. The result shows that the
volume energy and the symmetry energy are around the acceptable
values 16MeV and 30MeV respectively; the incompressibility is
unacceptably high in the linear model, but assumes reasonable value if
nonlinear terms are included; the density symmetry is around for
most parameter sets, and the symmetry incompressibility has positive sign
which is opposite to expectations based on the nonrelativistic model. In almost
all parameter sets there exists a critical point , where
the minimum and the maximum of the equation of state are coincident and the
incompressibility equals zero, falling into ranges
0.014fmfm and ; for a few
parameter sets there is no critical point and the pure neutron matter is
predicted to be bound. The maximum mass of neutron stars is predicted
in the range 2.45MM, the corresponding
neutron star radius is in the range 12.2kmkm.Comment: 10 pages, 5 figure
Quasirandom permutations are characterized by 4-point densities
For permutations π and τ of lengths |π|≤|τ| , let t(π,τ) be the probability that the restriction of τ to a random |π| -point set is (order) isomorphic to π . We show that every sequence {τj} of permutations such that |τj|→∞ and t(π,τj)→1/4! for every 4-point permutation π is quasirandom (that is, t(π,τj)→1/|π|! for every π ). This answers a question posed by Graham
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