258,975 research outputs found
Two-neutron transfer reactions and shape phase transitions in the microscopically-formulated interacting boson model
Two-neutron transfer reactions are studied within the interacting boson model
based on the nuclear energy density functional theory. Constrained
self-consistent mean-field calculations with the Skyrme energy density
functional are performed to provide microscopic input to completely determine
the Hamiltonian of the IBM. Spectroscopic properties are calculated only from
the nucleonic degrees of freedom. This method is applied to study the
and transfer reactions in the assorted set of rare-earth nuclei
Sm, Gd, and Dy, where
spherical-to-axially-deformed shape phase transition is suggested to occur at
the neutron number . The results are compared with those from the
purely phenomenological IBM calculations, as well as with the available
experimental data. The calculated and transfer reaction
intensities, from both the microscopic and phenomenological IBM frameworks,
signal the rapid nuclear structural change at particular nucleon numbers.Comment: 12 pages, 12 figures, 2 table
An ELU Network with Total Variation for Image Denoising
In this paper, we propose a novel convolutional neural network (CNN) for
image denoising, which uses exponential linear unit (ELU) as the activation
function. We investigate the suitability by analyzing ELU's connection with
trainable nonlinear reaction diffusion model (TNRD) and residual denoising. On
the other hand, batch normalization (BN) is indispensable for residual
denoising and convergence purpose. However, direct stacking of BN and ELU
degrades the performance of CNN. To mitigate this issue, we design an
innovative combination of activation layer and normalization layer to exploit
and leverage the ELU network, and discuss the corresponding rationale.
Moreover, inspired by the fact that minimizing total variation (TV) can be
applied to image denoising, we propose a TV regularized L2 loss to evaluate the
training effect during the iterations. Finally, we conduct extensive
experiments, showing that our model outperforms some recent and popular
approaches on Gaussian denoising with specific or randomized noise levels for
both gray and color images.Comment: 10 pages, Accepted by the 24th International Conference on Neural
Information Processing (2017
GMRES-Accelerated ADMM for Quadratic Objectives
We consider the sequence acceleration problem for the alternating direction
method-of-multipliers (ADMM) applied to a class of equality-constrained
problems with strongly convex quadratic objectives, which frequently arise as
the Newton subproblem of interior-point methods. Within this context, the ADMM
update equations are linear, the iterates are confined within a Krylov
subspace, and the General Minimum RESidual (GMRES) algorithm is optimal in its
ability to accelerate convergence. The basic ADMM method solves a
-conditioned problem in iterations. We give
theoretical justification and numerical evidence that the GMRES-accelerated
variant consistently solves the same problem in iterations
for an order-of-magnitude reduction in iterations, despite a worst-case bound
of iterations. The method is shown to be competitive against
standard preconditioned Krylov subspace methods for saddle-point problems. The
method is embedded within SeDuMi, a popular open-source solver for conic
optimization written in MATLAB, and used to solve many large-scale semidefinite
programs with error that decreases like , instead of ,
where is the iteration index.Comment: 31 pages, 7 figures. Accepted for publication in SIAM Journal on
Optimization (SIOPT
Interacting Individuals Leading to Zipf's Law
We present a general approach to explain the Zipf's law of city distribution.
If the simplest interaction (pairwise) is assumed, individuals tend to form
cities in agreement with the well-known statisticsComment: 4 pages 2 figure
Quantum Spin Hall and Quantum Anomalous Hall States Realized in Junction Quantum Wells
Both quantum spin Hall and quantum anomalous Hall states are novel states of
quantum matter with promising applications. We propose junction quantum wells
comprising II-VI, III-V or IV semiconductors as a large class of new materials
realizing the quantum spin Hall state. Especially, we find that the bulk band
gap for the quantum spin Hall state can be as large as 0.1 eV. Further more,
magnetic doping would induce the ferromagnetism in these junction quantum wells
due to band edge singularities in the band-inversion regime and to realize the
quantum anomalous Hall state.Comment: 5 pages, 4 figure
The State Equation of the Yang-Mills field Dark Energy Models
In this paper, we study the possibility of building Yang-Mills(YM) field dark
energy models with equation of state (EoS) crossing -1, and find that it can
not be realized by the single YM field models, no matter what kind of
lagrangian or initial condition. But the states of and
all can be naturally got in this kind of models. The former is like
a quintessence field, and the latter is like a phantom field. This makes that
one can build a model with two YM fields, in which one with the initial state
of , and the other with . We give an example model of
this kind, and find that its EoS is larger than -1 in the past and less than -1
at the present time. We also find that this change must be from to
, and it will go to the critical state of with the expansion
of the Universe, which character is same with the single YM field models, and
the Big Rip is naturally avoided.Comment: 20 pages, 4 figures. minor typos correcte
An MHD Model For Magnetar Giant Flares
Giant flares on soft gamma-ray repeaters that are thought to take place on
magnetars release enormous energy in a short time interval. Their power can be
explained by catastrophic instabilities occurring in the magnetic field
configuration and the subsequent magnetic reconnection. By analogy with the
coronal mass ejection (CME) events on the Sun, we develop a theoretical model
via an analytic approach for magnetar giant flares. In this model, the rotation
and/or displacement of the crust causes the field to twist and deform, leading
to flux rope formation in the magnetosphere and energy accumulation in the
related configuration. When the energy and helicity stored in the configuration
reach a threshold, the system loses its equilibrium, the flux rope is ejected
outward in a catastrophic way, and magnetic reconnection helps the catastrophe
develop to a plausible eruption. By taking SGR 1806 - 20 as an example, we
calculate the free magnetic energy released in such an eruptive process and
find that it is more than ergs, which is enough to power a giant
flare. The released free magnetic energy is converted into radiative energy,
kinetic energy and gravitational energy of the flux rope. We calculated the
light curves of the eruptive processes for the giant flares of SGR 1806 - 20,
SGR 0526-66 and SGR 1900+14, and compared them with the observational data. The
calculated light curves are in good agreement with the observed light curves of
giant flares.Comment: Accepted to Ap
Opportunistic Relaying in Time Division Broadcast Protocol with Incremental Relaying
In this paper, we investigate the performance of time division broadcast protocol (TDBC) with incremental relaying (IR) when there are multiple available relays. Opportunistic relaying (OR), i.e., the “best” relay is select for transmission to minimize the system’s outage probability, is proposed. Two OR schemes are presented. The first scheme, termed TDBC-OIR-I, selects the “best” relay from the set of relays that can decode both flows of signal from the two sources successfully. The second one, termed TDBC-OIR-II, selects two “best” relays from two respective sets of relays that can decode successfully each flow of signal. The performance, in terms of outage probability, expected rate (ER), and diversity-multiplexing tradeoff (DMT), of the two schemes are analyzed and compared with two TDBC schemes that have no IR but OR (termed TDBC-OR-I and TDBC-OR-II accordingly) and two other benchmark OR schemes that have no direct link transmission between the two sources
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