3,207 research outputs found
The largest virialized dark halo in the universe
Using semi-analytic approach, we present an estimate of the properties of the
largest virialized dark halos in the present universe for three different
scenarios of structure formation: SCDM, LCDM and OCDM models. The resulting
virial mass and temperature increase from the lowest values of and 9.8 keV in OCDM, the mid-range values of and 31 keV in LCDM, to the highest values of
, 65 keV in SCDM. As compared with the
largest virialized object seen in the universe, the richest clusters of
galaxies, we can safely rule out the OCDM model. In addition, the SCDM model is
very unlikely because of the unreasonably high virial mass and temperature. Our
computation favors the prevailing LCDM model in which superclusters may be
marginally regarded as dynamically-virialized systems.Comment: 5 pages, Accepted by Int. J. Mod. Phys.
Learning Garment DensePose for Robust Warping in Virtual Try-On
Virtual try-on, i.e making people virtually try new garments, is an active
research area in computer vision with great commercial applications. Current
virtual try-on methods usually work in a two-stage pipeline. First, the garment
image is warped on the person's pose using a flow estimation network. Then in
the second stage, the warped garment is fused with the person image to render a
new try-on image. Unfortunately, such methods are heavily dependent on the
quality of the garment warping which often fails when dealing with hard poses
(e.g., a person lifting or crossing arms). In this work, we propose a robust
warping method for virtual try-on based on a learned garment DensePose which
has a direct correspondence with the person's DensePose. Due to the lack of
annotated data, we show how to leverage an off-the-shelf person DensePose model
and a pretrained flow model to learn the garment DensePose in a weakly
supervised manner. The garment DensePose allows a robust warping to any
person's pose without any additional computation. Our method achieves the
state-of-the-art equivalent on virtual try-on benchmarks and shows warping
robustness on in-the-wild person images with hard poses, making it more suited
for real-world virtual try-on applications.Comment: 6 page
Shared memory parallel computing procedures for nonlinear dynamic analysis of super high rise buildings
The proposed parallel state transformation procedures (PSTP) of fiber beam-column elements and multi-layered shell elements, combined with the parallel factorization of Jacobian (PF), are incorporated into a finite element program. In PSTP, elements are classified into different levels of workload prior to state determination in order to balance workload among different threads. In PF, the multi-threaded version of OpenBLAS is adopted to compute super-nodes. A case study on four super high-rise buildings, i.e. S1~S4, has demonstrated that the combination of PSTP and PF does not have any observable influence on computational accuracy. As number of elements and DOFs increases, the ratio of time consumed in the formation of the Jacobian to that consumed in the solution of algebraic equations tends to decrease. The introduction of parallel solver can yield a substantial reduction in computational cost. Combination of PSTP and PF can give rise to a further significant reduction. The acceleration ratios associated with PSTP do not exhibit a significant decrease as PGA level increases. Even PGA level is equal to 2.0g, PSTP still can result in acceleration ratios of 2.56 and 1.92 for S1 and S4, respectively. It is verified that it is more effective to accelerate analysis by reducing the time spent in solving algebraic equations rather than reducing that spent in the formation of the Jacobian for super high-rise buildings
Application of RetCamâ…¡ in the screening of neonatal fundus disease
AIM: To investigate the safe and reliable examination method for neonatal fundus screening.<p>METHODS: Fundus information of 2 836 neonates performed by RetCamâ…¡ in our hospital from January 1, 2012 to December 31, 2012 were retrospectively analyzed, including 1 625 cases(57.30%)of premature infants which were first examined 1-4 weeks after birth and 1 211 cases(42.70%)of term infants which were first examined within 4 weeks after birth.<p>RESULTS: Totally 454 cases of abnormalfundus were found, including 207 cases(12.74%)of retinopathy of prematurity(ROP), ROPâ… in 118 cases(57%), ROPâ…¡ in 58 cases(28.02%), ROPâ…¢ in 23 cases(11.11%), ROPâ…£ in 8 cases(3.86%), no case of ROPV. A total of 247(20.40%)term infants had abnormal fundus, of which 68 cases(27.53%)were developmental or hereditary disease, retinoblastoma in 1 case(0.40%), retinal hemorrhage in 102 cases(41.30%), retinal exudative changes in 68 cases(27.53%), optic atrophy in 5 cases(2.02%)and optic disc edema in 3 cases(1.21%).<p>CONCLUSION: Neonatal fundus diseases were so various and harmful that early screening should be attended to. Premature infants and term infants with high risk are treated as focus group of fundus screening and RetCamII examination is safe and effective
Preparation and characterization of a sulfonated carbon-based solid acid microspheric material (SCSAM) and its use for the esterification of oleic acid with methanol
In this study, a sulfonated group (-SO3H) rich carbon-based solid acid microspheric material was prepared by hydrothermal method followed by sulfonation using glucose as the raw material. Such a green, non-corrosive, and renewable carbon material was used as a heterogeneous catalyst for the esterification of oleic acid with methanol for the production of biodiesel. The carbon microspheres were characterized systematically. It was found that the carbon microspheres prepared under the optimal reaction conditions exhibited smooth surfaces, uniform particle sizes and good dispersion. The sulfonated carbon-based solid acid microspheric materials showed high acidity and good catalytic activities for the esterification of oleic acid with methanol. The influence of reaction operating conditions on the performance of esterification was studied. The optimal esterification reaction conditions were found to be: methanol/oleic acid molar ratio 12:1, catalyst loading 0.25 g (0.05 mmol H+), reaction temperature 65 °C, reaction time 8 h and mechanical stirring rate 360 rpm. It was found that the catalyst demonstrated very good reusability although there was noticeable loss in acidity due to the leaching of active sites
Generative Model Based Noise Robust Training for Unsupervised Domain Adaptation
Target domain pseudo-labelling has shown effectiveness in unsupervised domain
adaptation (UDA). However, pseudo-labels of unlabeled target domain data are
inevitably noisy due to the distribution shift between source and target
domains. This paper proposes a Generative model-based Noise-Robust Training
method (GeNRT), which eliminates domain shift while mitigating label noise.
GeNRT incorporates a Distribution-based Class-wise Feature Augmentation (D-CFA)
and a Generative-Discriminative classifier Consistency (GDC), both based on the
class-wise target distributions modelled by generative models. D-CFA minimizes
the domain gap by augmenting the source data with distribution-sampled target
features, and trains a noise-robust discriminative classifier by using target
domain knowledge from the generative models. GDC regards all the class-wise
generative models as generative classifiers and enforces a consistency
regularization between the generative and discriminative classifiers. It
exploits an ensemble of target knowledge from all the generative models to
train a noise-robust discriminative classifier and eventually gets
theoretically linked to the Ben-David domain adaptation theorem for reducing
the domain gap. Extensive experiments on Office-Home, PACS, and Digit-Five show
that our GeNRT achieves comparable performance to state-of-the-art methods
under single-source and multi-source UDA settings
Prediction Calibration for Generalized Few-shot Semantic Segmentation
Generalized Few-shot Semantic Segmentation (GFSS) aims to segment each image
pixel into either base classes with abundant training examples or novel classes
with only a handful of (e.g., 1-5) training images per class. Compared to the
widely studied Few-shot Semantic Segmentation FSS, which is limited to
segmenting novel classes only, GFSS is much under-studied despite being more
practical. Existing approach to GFSS is based on classifier parameter fusion
whereby a newly trained novel class classifier and a pre-trained base class
classifier are combined to form a new classifier. As the training data is
dominated by base classes, this approach is inevitably biased towards the base
classes. In this work, we propose a novel Prediction Calibration Network PCN to
address this problem. Instead of fusing the classifier parameters, we fuse the
scores produced separately by the base and novel classifiers. To ensure that
the fused scores are not biased to either the base or novel classes, a new
Transformer-based calibration module is introduced. It is known that the
lower-level features are useful of detecting edge information in an input image
than higher-level features. Thus, we build a cross-attention module that guides
the classifier's final prediction using the fused multi-level features.
However, transformers are computationally demanding. Crucially, to make the
proposed cross-attention module training tractable at the pixel level, this
module is designed based on feature-score cross-covariance and episodically
trained to be generalizable at inference time. Extensive experiments on
PASCAL- and COCO- show that our PCN outperforms the
state-the-the-art alternatives by large margins.Comment: Technical Repor
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