38,398 research outputs found
COCO_TS Dataset: Pixel-level Annotations Based on Weak Supervision for Scene Text Segmentation
The absence of large scale datasets with pixel-level supervisions is a
significant obstacle for the training of deep convolutional networks for scene
text segmentation. For this reason, synthetic data generation is normally
employed to enlarge the training dataset. Nonetheless, synthetic data cannot
reproduce the complexity and variability of natural images. In this paper, a
weakly supervised learning approach is used to reduce the shift between
training on real and synthetic data. Pixel-level supervisions for a text
detection dataset (i.e. where only bounding-box annotations are available) are
generated. In particular, the COCO-Text-Segmentation (COCO_TS) dataset, which
provides pixel-level supervisions for the COCO-Text dataset, is created and
released. The generated annotations are used to train a deep convolutional
neural network for semantic segmentation. Experiments show that the proposed
dataset can be used instead of synthetic data, allowing us to use only a
fraction of the training samples and significantly improving the performances
Thermal optical non-linearity of nematic mesophase enhanced by gold nanoparticles – an experimental and numerical investigation
In this work the mechanisms leading to the enhancement of optical nonlinearity of nematic liquid crystalline material through localized heating by doping the liquid crystals (LCs) with gold nanoparticles (GNPs) are investigated. We present some experimental and theoretical results on the effect of voltage and nanoparticle concentration on the nonlinear response of GNP-LC suspensions. The optical nonlinearity of these systems is characterized by diffraction measurements and the second order nonlinear refractive index, n 2 , is used to compare systems with different configurations and operating conditions. A theoretical model based on heat diffusion that takes into account the intensity and finite size of the incident beam, the nanoparticle concentration dependent absorbance of GNP doped LC systems and the presence of bounding substrates is developed and validated. We use the model to discuss the possibilities of further enhancing the optical nonlinearity
Temporal and spatial distribution pattern of Bullacta exarata in a tidal flat at south shore of Hangzhou Bay, China
The distribution pattern of Bullacta exarata was studied in different seasons of 2004 at south shore of Hangzhou Bay, China. We found that the distribution pattern of B. exarata was aggregated in each season by Taylor's power regression and Iwao's plot regresses methods (P < 0.001). Based on two-way ANOVA analysis, the results indicated that the densities were significantly affected by the factors of season (P < 0.001), distance to the dyked dam (P < 0.001) and the interaction between them (P < 0.001). The densities distribution followed with the distance gradient was significantly different in each season with one-way ANOVA analysis. The results of Pearson correlation coefficients analysis on data of density indicated that in the warmer seasons (spring and summer) the highest densities occurred at 150 m to the dyked dam, while in the cooler seasons peak in densities were at 250 m to the dyked dam (autumn and winter). In the study area, seasonal variation of B. exarata densities should be the response of the species to the environmental change, especially the food resource
Self-organization of vortices in type-II superconductors during magnetic relaxation
We revise the applicability of the theory of self-organized criticality (SOC)
to the process of magnetic relaxation in type-II superconductors. The driving
parameter of self-organization of vortices is the energy barrier for flux creep
and not the current density. The power spectrum of the magnetic noise due to
vortex avalanches is calculated and is predicted to vary with time during
relaxation.Comment: RevTex, 5 pages, 2 PS figures. Accepted in Phys. Rev.
Optical study of MgTiO: Evidence for an orbital-Peierls state
Dimension reduction due to the orbital ordering has recently been proposed to
explain the exotic charge, magnetic and structural transitions in some
three-dimensional (3D) transitional metal oxides. We present optical
measurement on a spinel compound MgTiO which undergoes a sharp
metal-insulator transition at 240 K, and show that the spectral change across
the transition can be well understood from the proposed picture of 1D Peierls
transition driven by the ordering of and orbitals. We further
elaborate that the orbital-driven instability picture applies also very well to
the optical data of another spinel CuIrS reported earlier.Comment: 5 pages, 6 figures, to be published in Phys. Rev.
Nonequilibrium Phase Transitions of Vortex Matter in Three-Dimensional Layered Superconductors
Large-scale simulations on three-dimensional (3D) frustrated anisotropic XY
model have been performed to study the nonequilibrium phase transitions of
vortex matter in weak random pinning potential in layered superconductors. The
first-order phase transition from the moving Bragg glass to the moving smectic
is clarified, based on thermodynamic quantities. A washboard noise is observed
in the moving Bragg glass in 3D simulations for the first time. It is found
that the activation of the vortex loops play the dominant role in the dynamical
melting at high drive.Comment: 3 pages,5 figure
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