32,038 research outputs found
Comment on "Vortex Liquid Crystal in Anisotropic Type II Superconductors"
This is a Comment on "Vortex Liquid Crystal in Anisotropic Type II
Superconductors" by E. W. Carlson et al. in PRL, vol.90, 087001 (2003)
[cond-mat/0209175].Comment: 2 pages, 1 figure, revised versio
Collective modes of a harmonically trapped one-dimensional Bose gas: the effects of finite particle number and nonzero temperature
Following the idea of the density functional approach, we develop a
generalized Bogoliubov theory of an interacting Bose gas confined in a
one-dimensional harmonic trap, by using a local chemical potential - calculated
with the Lieb-Liniger exact solution - as the exchange energy. At zero
temperature, we use the theory to describe collective modes of a
finite-particle system in all interaction regimes from the ideal gas limit, to
the mean-field Thomas-Fermi regime, and to the strongly interacting
Tonks-Girardeau regime. At finite temperature, we investigate the temperature
dependence of collective modes in the weak-coupling regime by means of a
Hartree-Fock-Bogoliubov theory with Popov approximation. By emphasizing the
effects of finite particle number and nonzero temperature on collective mode
frequencies, we make comparisons of our results with the recent experimental
measurement [E. Haller et al., Science 325, 1224 (2009)] and some previous
theoretical predictions. We show that the experimental data are still not fully
explained within current theoretical framework.Comment: 10 pages, 8 figure
A generalized exchange-correlation functional: the Neural-Networks approach
A Neural-Networks-based approach is proposed to construct a new type of
exchange-correlation functional for density functional theory. It is applied to
improve B3LYP functional by taking into account of high-order contributions to
the exchange-correlation functional. The improved B3LYP functional is based on
a neural network whose structure and synaptic weights are determined from 116
known experimental atomization energies, ionization potentials, proton
affinities or total atomic energies which were used by Becke in his pioneer
work on the hybrid functionals [J. Chem. Phys. , 5648 (1993)]. It
leads to better agreement between the first-principles calculation results and
these 116 experimental data. The new B3LYP functional is further tested by
applying it to calculate the ionization potentials of 24 molecules of the G2
test set. The 6-311+G(3{\it df},2{\it p}) basis set is employed in the
calculation, and the resulting root-mean-square error is reduced to 2.2
kcalmol in comparison to 3.6 kcalmol of
conventional B3LYP/6-311+G(3{\it df},2{\it p}) calculation.Comment: 10 pages, 1figur
Non-isospectral extension of the Volterra lattice hierarchy, and Hankel determinants
For the first two equations of the Volterra lattice hierarchy and the first
two equations of its non-autonomous (non-isospectral) extension, we present
Riccati systems for functions c_j(t), j=0,1,..., such that an expression in
terms of Hankel determinants built from them solves these equations on the
right half of the lattice. This actually achieves a complete linearization of
these equations of the extended Volterra lattice hierarchy.Comment: 31 pages, 3rd version: introduction extended, part of Section 2 moved
there, Appendix D added, additional references, to appear in Nonlinearit
Enhancing Grasping Performance of Novel Objects through an Improved Fine-Tuning Process
Grasping algorithms have evolved from planar depth grasping to utilizing
point cloud information, allowing for application in a wider range of
scenarios. However, data-driven grasps based on models trained on basic
open-source datasets may not perform well on novel objects, which are often
required in different scenarios, necessitating fine-tuning using new objects.
The data driving these algorithms essentially corresponds to the closing region
of the hand in 6D pose, and due to the uniqueness of 6D pose, synthetic
annotation or real-machine annotation methods are typically employed. Acquiring
large amounts of data with real-machine annotation is challenging, making
synthetic annotation a common practice. However, obtaining annotated 6D pose
data using conventional methods is extremely time-consuming. Therefore, we
propose a method to quickly acquire data for novel objects, enabling more
efficient fine-tuning. Our method primarily samples grasp orientations to
generate and annotate grasps. Experimental results demonstrate that our
fine-tuning process for a new object is 400 \% faster than other methods.
Furthermore, we propose an optimized grasp annotation framework that accounts
for the effects of the gripper closing, making the annotations more reasonable.
Upon acceptance of this paper, we will release our algorithm as open-source
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