174 research outputs found
Homogeneity Pursuit in Single Index Models based Panel Data Analysis
Panel data analysis is an important topic in statistics and econometrics.
Traditionally, in panel data analysis, all individuals are assumed to share the
same unknown parameters, e.g. the same coefficients of covariates when the
linear models are used, and the differences between the individuals are
accounted for by cluster effects. This kind of modelling only makes sense if
our main interest is on the global trend, this is because it would not be able
to tell us anything about the individual attributes which are sometimes very
important. In this paper, we proposed a modelling based on the single index
models embedded with homogeneity for panel data analysis, which builds the
individual attributes in the model and is parsimonious at the same time. We
develop a data driven approach to identify the structure of homogeneity, and
estimate the unknown parameters and functions based on the identified
structure. Asymptotic properties of the resulting estimators are established.
Intensive simulation studies conducted in this paper also show the resulting
estimators work very well when sample size is finite. Finally, the proposed
modelling is applied to a public financial dataset and a UK climate dataset,
the results reveal some interesting findings.Comment: 46 pages, 2 figure
Towards Good Practices for Deep 3D Hand Pose Estimation
3D hand pose estimation from single depth image is an important and
challenging problem for human-computer interaction. Recently deep convolutional
networks (ConvNet) with sophisticated design have been employed to address it,
but the improvement over traditional random forest based methods is not so
apparent. To exploit the good practice and promote the performance for hand
pose estimation, we propose a tree-structured Region Ensemble Network (REN) for
directly 3D coordinate regression. It first partitions the last convolution
outputs of ConvNet into several grid regions. The results from separate
fully-connected (FC) regressors on each regions are then integrated by another
FC layer to perform the estimation. By exploitation of several training
strategies including data augmentation and smooth loss, proposed REN can
significantly improve the performance of ConvNet to localize hand joints. The
experimental results demonstrate that our approach achieves the best
performance among state-of-the-art algorithms on three public hand pose
datasets. We also experiment our methods on fingertip detection and human pose
datasets and obtain state-of-the-art accuracy.Comment: Extended version of arXiv:1702.0244
Pose Guided Structured Region Ensemble Network for Cascaded Hand Pose Estimation
Hand pose estimation from a single depth image is an essential topic in
computer vision and human computer interaction. Despite recent advancements in
this area promoted by convolutional neural network, accurate hand pose
estimation is still a challenging problem. In this paper we propose a Pose
guided structured Region Ensemble Network (Pose-REN) to boost the performance
of hand pose estimation. The proposed method extracts regions from the feature
maps of convolutional neural network under the guide of an initially estimated
pose, generating more optimal and representative features for hand pose
estimation. The extracted feature regions are then integrated hierarchically
according to the topology of hand joints by employing tree-structured fully
connections. A refined estimation of hand pose is directly regressed by the
proposed network and the final hand pose is obtained by utilizing an iterative
cascaded method. Comprehensive experiments on public hand pose datasets
demonstrate that our proposed method outperforms state-of-the-art algorithms.Comment: Accepted by Neurocomputin
Motion Feature Augmented Recurrent Neural Network for Skeleton-based Dynamic Hand Gesture Recognition
Dynamic hand gesture recognition has attracted increasing interests because
of its importance for human computer interaction. In this paper, we propose a
new motion feature augmented recurrent neural network for skeleton-based
dynamic hand gesture recognition. Finger motion features are extracted to
describe finger movements and global motion features are utilized to represent
the global movement of hand skeleton. These motion features are then fed into a
bidirectional recurrent neural network (RNN) along with the skeleton sequence,
which can augment the motion features for RNN and improve the classification
performance. Experiments demonstrate that our proposed method is effective and
outperforms start-of-the-art methods.Comment: Accepted by ICIP 201
Exploring the convective core of the hybrid Scuti- Doradus star CoRoT 100866999 with asteroseismology
We computed a grid of theoretical models to fit the Scuti
frequencies of CoRoT 100866999 detected earlier from the CoRoT timeserials. The
pulsating primary star is determined to be a main sequence star with a rotation
period of days, rotating slower than the orbital motion.
The fundamental parameters of the primary star are determined to be =
, , =
, = K, =
, = ,
= , and =
0.488, matching well those obtained from the eclipsing
light curve analysis. Based on the model fittings, and are
suggested to be two dipole modes, and , , , and to be four
quadrupole modes. In particular, and are identified as two
components of one quintuplet. Based on the best-fitting model, we find that
is a g mode and the other nonradial modes have pronounced mixed
characters, which give strong constraints on the convective core. Finally, the
relative size of the convective core of CoRoT 100866999 is determined to
= .Comment: 7 figures and 6 tables. accepted by Ap
Look More Than Once: An Accurate Detector for Text of Arbitrary Shapes
Previous scene text detection methods have progressed substantially over the
past years. However, limited by the receptive field of CNNs and the simple
representations like rectangle bounding box or quadrangle adopted to describe
text, previous methods may fall short when dealing with more challenging text
instances, such as extremely long text and arbitrarily shaped text. To address
these two problems, we present a novel text detector namely LOMO, which
localizes the text progressively for multiple times (or in other word, LOok
More than Once). LOMO consists of a direct regressor (DR), an iterative
refinement module (IRM) and a shape expression module (SEM). At first, text
proposals in the form of quadrangle are generated by DR branch. Next, IRM
progressively perceives the entire long text by iterative refinement based on
the extracted feature blocks of preliminary proposals. Finally, a SEM is
introduced to reconstruct more precise representation of irregular text by
considering the geometry properties of text instance, including text region,
text center line and border offsets. The state-of-the-art results on several
public benchmarks including ICDAR2017-RCTW, SCUT-CTW1500, Total-Text, ICDAR2015
and ICDAR17-MLT confirm the striking robustness and effectiveness of LOMO.Comment: Accepted by CVPR1
Bayesian Nonparametric Dictionary Learning for Compressed Sensing MRI
We develop a Bayesian nonparametric model for reconstructing magnetic
resonance images (MRI) from highly undersampled k-space data. We perform
dictionary learning as part of the image reconstruction process. To this end,
we use the beta process as a nonparametric dictionary learning prior for
representing an image patch as a sparse combination of dictionary elements. The
size of the dictionary and the patch-specific sparsity pattern are inferred
from the data, in addition to other dictionary learning variables. Dictionary
learning is performed directly on the compressed image, and so is tailored to
the MRI being considered. In addition, we investigate a total variation penalty
term in combination with the dictionary learning model, and show how the
denoising property of dictionary learning removes dependence on regularization
parameters in the noisy setting. We derive a stochastic optimization algorithm
based on Markov Chain Monte Carlo (MCMC) for the Bayesian model, and use the
alternating direction method of multipliers (ADMM) for efficiently performing
total variation minimization. We present empirical results on several MRI,
which show that the proposed regularization framework can improve
reconstruction accuracy over other methods
CYCLADES: Conflict-free Asynchronous Machine Learning
We present CYCLADES, a general framework for parallelizing stochastic
optimization algorithms in a shared memory setting. CYCLADES is asynchronous
during shared model updates, and requires no memory locking mechanisms, similar
to HOGWILD!-type algorithms. Unlike HOGWILD!, CYCLADES introduces no conflicts
during the parallel execution, and offers a black-box analysis for provable
speedups across a large family of algorithms. Due to its inherent conflict-free
nature and cache locality, our multi-core implementation of CYCLADES
consistently outperforms HOGWILD!-type algorithms on sufficiently sparse
datasets, leading to up to 40% speedup gains compared to the HOGWILD!
implementation of SGD, and up to 5x gains over asynchronous implementations of
variance reduction algorithms
HourNAS: Extremely Fast Neural Architecture Search Through an Hourglass Lens
Neural Architecture Search (NAS) refers to automatically design the
architecture. We propose an hourglass-inspired approach (HourNAS) for this
problem that is motivated by the fact that the effects of the architecture
often proceed from the vital few blocks. Acting like the narrow neck of an
hourglass, vital blocks in the guaranteed path from the input to the output of
a deep neural network restrict the information flow and influence the network
accuracy. The other blocks occupy the major volume of the network and determine
the overall network complexity, corresponding to the bulbs of an hourglass. To
achieve an extremely fast NAS while preserving the high accuracy, we propose to
identify the vital blocks and make them the priority in the architecture
search. The search space of those non-vital blocks is further shrunk to only
cover the candidates that are affordable under the computational resource
constraints. Experimental results on the ImageNet show that only using 3 hours
(0.1 days) with one GPU, our HourNAS can search an architecture that achieves a
77.0% Top-1 accuracy, which outperforms the state-of-the-art methods
Coverless Video Steganography based on Maximum DC Coefficients
Coverless steganography has been a great interest in recent years, since it
is a technology that can absolutely resist the detection of steganalysis by not
modifying the carriers. However, most existing coverless steganography
algorithms select images as carriers, and few studies are reported on coverless
video steganography. In fact, video is a securer and more informative carrier.
In this paper, a novel coverless video steganography algorithm based on maximum
Direct Current (DC) coefficients is proposed. Firstly, a Gaussian distribution
model of DC coefficients considering video coding process is built, which
indicates that the distribution of changes for maximum DC coefficients in a
block is more stable than the adjacent DC coefficients. Then, a novel hash
sequence generation method based on the maximum DC coefficients is proposed.
After that, the video index structure is established to speed up the efficiency
of searching videos. In the process of information hiding, the secret
information is converted into binary segments, and the video whose hash
sequence equals to secret information segment is selected as the carrier
according to the video index structure. Finally, all of the selected videos and
auxiliary information are sent to the receiver. Especially, the subjective
security of video carriers, the cost of auxiliary information and the
robustness to video compression are considered for the first time in this
paper. Experimental results and analysis show that the proposed algorithm
performs better in terms of capacity, robustness, and security, compared with
the state-of-the-art coverless steganography algorithms
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