29,038 research outputs found
Membrane paradigm of black holes in Chern-Simons modified gravity
The membrane paradigm of black hole is studied in the Chern-Simons modified
gravity. Derived with the action principle a la Parikh-Wilczek, the stress
tensor of membrane manifests a rich structure arising from the Chern-Simons
term. The membrane stress tensor, if related to the bulk stress tensor in a
special form, obeys the low-dimensional fluid continuity equation and the
Navier-Stokes equation. This paradigm is applied to spherically symmetric
static geometries, and in particular, the Schwarzschild black hole, which is a
solution of a large class of dynamical Chern-Simons gravity.Comment: 16 pages, author information update
Smoothing methods comparison for CMB E- and B-mode separation
The anisotropies of the B-mode polarization in the cosmic microwave
background radiation play a crucial role for the study of the very early
Universe. However, in the real observation, the mixture of the E-mode and
B-mode can be caused by the partial sky surveys, which must be separated before
applied to the cosmological explanation. The separation method developed by
Smith (\citealt{PhysRevD.74.083002}) has been widely adopted, where the edge of
the top-hat mask should be smoothed to avoid the numerical errors. In this
paper, we compare three different smoothing methods, and investigate the
leakage residuals of the E-B mixture. We find that, if the less information
loss is needed and the smaller region is smoothed in the analysis, the
\textit{sin}- and \textit{cos}-smoothing methods are better. However, if we
need a clean constructed B-mode map, the larger region around the mask edge
should be smoothed. In this case, the \textit{Gaussian}-smoothing method
becomes much better. In addition, we find that the leakage caused by the
numerical errors in the \textit{Gaussian}-smoothing method mostly concentrates
on two bands, which is quite easy to be reduced for the further E-B
separations.Comment: 14 pages, 7 figures, RAA accepte
Effective Blog Pages Extractor for Better UGC Accessing
Blog is becoming an increasingly popular media for information publishing.
Besides the main content, most of blog pages nowadays also contain noisy
information such as advertisements etc. Removing these unrelated elements can
improves user experience, but also can better adapt the content to various
devices such as mobile phones. Though template-based extractors are highly
accurate, they may incur expensive cost in that a large number of template need
to be developed and they will fail once the template is updated. To address
these issues, we present a novel template-independent content extractor for
blog pages. First, we convert a blog page into a DOM-Tree, where all elements
including the title and body blocks in a page correspond to subtrees. Then we
construct subtree candidate set for the title and the body blocks respectively,
and extract both spatial and content features for elements contained in the
subtree. SVM classifiers for the title and the body blocks are trained using
these features. Finally, the classifiers are used to extract the main content
from blog pages. We test our extractor on 2,250 blog pages crawled from nine
blog sites with obviously different styles and templates. Experimental results
verify the effectiveness of our extractor.Comment: 2016 3rd International Conference on Information Science and Control
Engineering (ICISCE
Constructing Calabi-Yau Metrics From Hyperkahler Spaces
Recently, a metric construction for the Calabi-Yau 3-folds from a
four-dimensional hyperkahler space by adding a complex line bundle was
proposed. We extend the construction by adding a U(1) factor to the holomorphic
(3,0)-form, and obtain the explicit formalism for a generic hyperkahler base.
We find that a discrete choice arises: the U(1) factor can either depend solely
on the fibre coordinates or vanish. In each case, the metric is determined by
one differential equation for the modified Kahler potential. As explicit
examples, we obtain the generalized resolutions (up to orbifold singularity) of
the cone of the Einstein-Sasaki spaces Y^{p,q}. We also obtain a large class of
new singular CY3 metrics with SU(2)\times U(1) or SU(2)\times U(1)^2
isometries.Comment: 29 pages, no figures, version appeared in Classical and Quantum
Gravit
Maximum mutual information regularized classification
In this paper, a novel pattern classification approach is proposed by
regularizing the classifier learning to maximize mutual information between the
classification response and the true class label. We argue that, with the
learned classifier, the uncertainty of the true class label of a data sample
should be reduced by knowing its classification response as much as possible.
The reduced uncertainty is measured by the mutual information between the
classification response and the true class label. To this end, when learning a
linear classifier, we propose to maximize the mutual information between
classification responses and true class labels of training samples, besides
minimizing the classification error and reduc- ing the classifier complexity.
An objective function is constructed by modeling mutual information with
entropy estimation, and it is optimized by a gradi- ent descend method in an
iterative algorithm. Experiments on two real world pattern classification
problems show the significant improvements achieved by maximum mutual
information regularization
Patch-based Contour Prior Image Denoising for Salt and Pepper Noise
The salt and pepper noise brings a significant challenge to image denoising
technology, i.e. how to removal the noise clearly and retain the details
effectively? In this paper, we propose a patch-based contour prior denoising
approach for salt and pepper noise. First, noisy image is cut into patches as
basic representation unit, a discrete total variation model is designed to
extract contour structures; Second, a weighted Euclidean distance is designed
to search the most similar patches, then, corresponding contour stencils are
extracted from these similar patches; At the last, we build filter from contour
stencils in the framework of regression. Numerical results illustrate that the
proposed method is competitive with the state-of-the-art methods in terms of
the peak signal-to-noise (PSNR) and visual effects
Normal heat conduction in lattice models with asymmetry harmonic interparticle interactions
We study the thermal conduction behaviors of one-dimensional lattice models
with asymmetry harmonic interparticle interactions in this paper. Normal
thermal conductivity independent of the system size is observed when the
lattice chains are long enough. Because only the harmonic interactions are
involved, the result confirms without ambiguous interpretation that the
asymmetry plays key role in resulting in the normal thermal conduction in
one-dimensional momentum conserving lattices. Both equilibrium and
nonequilibrium simulations are performed to support the conclusion.Comment: 4 pages,3 figure
Deep Learning-Based Gait Recognition Using Smartphones in the Wild
Compared to other biometrics, gait is difficult to conceal and has the
advantage of being unobtrusive. Inertial sensors, such as accelerometers and
gyroscopes, are often used to capture gait dynamics. These inertial sensors are
commonly integrated into smartphones and are widely used by the average person,
which makes gait data convenient and inexpensive to collect. In this paper, we
study gait recognition using smartphones in the wild. In contrast to
traditional methods, which often require a person to walk along a specified
road and/or at a normal walking speed, the proposed method collects inertial
gait data under unconstrained conditions without knowing when, where, and how
the user walks. To obtain good person identification and authentication
performance, deep-learning techniques are presented to learn and model the gait
biometrics based on walking data. Specifically, a hybrid deep neural network is
proposed for robust gait feature representation, where features in the space
and time domains are successively abstracted by a convolutional neural network
and a recurrent neural network. In the experiments, two datasets collected by
smartphones for a total of 118 subjects are used for evaluations. The
experiments show that the proposed method achieves higher than 93.5\% and
93.7\% accuracies in person identification and authentication, respectively.Comment: IEEE Transactions on Information Forensics and Security, 15(1), 202
Unsupervised Learning Layers for Video Analysis
This paper presents two unsupervised learning layers (UL layers) for
label-free video analysis: one for fully connected layers, and the other for
convolutional ones. The proposed UL layers can play two roles: they can be the
cost function layer for providing global training signal; meanwhile they can be
added to any regular neural network layers for providing local training signals
and combined with the training signals backpropagated from upper layers for
extracting both slow and fast changing features at layers of different depths.
Therefore, the UL layers can be used in either pure unsupervised or
semi-supervised settings. Both a closed-form solution and an online learning
algorithm for two UL layers are provided. Experiments with unlabeled synthetic
and real-world videos demonstrated that the neural networks equipped with UL
layers and trained with the proposed online learning algorithm can extract
shape and motion information from video sequences of moving objects. The
experiments demonstrated the potential applications of UL layers and online
learning algorithm to head orientation estimation and moving object
localization
Multi transitions in MgB2 films prepared by pulsed laser deposition
We have grown MgB2 films in a postannealing process. Precursors were prepared
on Al2O3(0001) substrates by codeposition of Mg and MgB2 using pulsed laser
deposition technique. Superconducting MgB2 thin films were obtained via an ex
situ postannealing process, with various annealing temperatures and durations.
In magnetic measurement we found more than one transitions in almost all the
samples, and the temperature dependence of the resistance confirmed this
phenomena. We proved this is not result of magnesium deficiency. Transportation
properties of MgB2 thin films under strong magnetic fields are also studied.Comment: 17 pages, 2 tables, 7 figure
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