232 research outputs found
Automatic Object-Oriented, Spectral-Spatial Feature Extraction Driven by Tobler’s First Law of Geography for Very High Resolution Aerial Imagery Classification
(This article belongs to the Special Issue Recent Trends in UAV Remote Sensing)Aerial image classification has become popular and has attracted extensive research efforts in recent decades. The main challenge lies in its very high spatial resolution but relatively insufficient spectral information. To this end, spatial-spectral feature extraction is a popular strategy for classification. However, parameter determination for that feature extraction is usually time-consuming and depends excessively on experience. In this paper, an automatic spatial feature extraction approach based on image raster and segmental vector data cross-analysis is proposed for the classification of very high spatial resolution (VHSR) aerial imagery. First, multi-resolution segmentation is used to generate strongly homogeneous image objects and extract corresponding vectors. Then, to automatically explore the region of a ground target, two rules, which are derived from Tobler’s First Law of Geography (TFL) and a topological relationship of vector data, are integrated to constrain the extension of a region around a central object. Third, the shape and size of the extended region are described. A final classification map is achieved through a supervised classifier using shape, size, and spectral features. Experiments on three real aerial images of VHSR (0.1 to 0.32 m) are done to evaluate effectiveness and robustness of the proposed approach. Comparisons to state-of-the-art methods demonstrate the superiority of the proposed method in VHSR image classification.Peer Reviewe
Pore Structure Characterization and Transport Performance Simulation of Cement Hydration Based on Irregular Particles
Based on the CEMHYD3D hydration model, the irregular cement particles were introduced into the model, and three 3D micro structures under different water cement ratio (0.23, 0.35, 0.53) were obtained. Numerous physical models for calculating the characteristic parameters of pore structure are established and the characteristic parameters of pore structure obtained from the physical models. The characteristic parameters of pore structure include the total porosity (referred to as porosity), the porosity of continuous pore, isolated pore and dead-end pore, connectivity, pore size distribution and tortuosity. Finally, the transmission coefficient of each micro structure is calculated by the electric simulation method
Dynamic surface tension of the pure liquid-vapor interface subjected to the cyclic loads
We demonstrate a methodology for computationally investigating the mechanical
response of a pure molten lead surface system to the lateral mechanical cyclic
loads and try to answer the question: how dose the dynamically driven liquid
surface system follow the classical physics of the elastic-driven oscillation?
The steady-state oscillation of the dynamic surface tension under cyclic load,
including the excitation of high frequency vibration mode at different driving
frequencies and amplitudes, was compared with the classical theory of
single-body driven damped oscillator. Under the highest studied frequency (50
GHz) and amplitude (5%) of the load, the increase of the (mean value) dynamic
surface tension could reach ~5%. The peak and trough values of the
instantaneous dynamic surface tension could reach (up to) 40% increase and (up
to) 20% decrease compared to the equilibrium surface tension, respectively. The
extracted generalized natural frequencies and the generalized damping constants
seem to be intimately related to the intrinsic timescales of the atomic
temporal-spatial correlation functions of the liquids both in the bulk region
and in the outermost surface layers. These insights uncovered could be helpful
for quantitative manipulation of the liquid surface tension using ultrafast
shockwaves or laser pulses
The PEG-PCL-PEG Hydrogel as an Implanted Ophthalmic Delivery System after Glaucoma Filtration Surgery; a Pilot Study
Currently, filtration surgery has been considered as the most effective therapy for glaucoma; however, the scar formation in the surgical area may often lead to failure to the procedure. An implanted drug delivery system may provide localized and sustained release of a drug over an extended period. Poly (ethylene glycol)-poly (ε-caprolactone)-poly (ethylene glycol) (PEG-PCL-PEG, PECE) hydrogel has been successfully synthesized and determined as thermosensitive and biocompatible. In order to overcome the limitations of common local ophthalmic medications, we investigated the function of a self-assembled PECE hydrogel as an intracameral injection-implanted drug carrier to inhibit the formation of postoperative scarring. Following intraoperative administration bevacizumab-loaded hydrogel intracameral was injected into rabbit eyes; the status of the bleb and filtration fistula formed following the filtering surgery were also examined through pathologic evaluation. Due to the sustained release of bevacizumab from the hydrogel, neovascularization and scar formation were inhibited; moreover, there were no corneal abnormalities and other ocular tissue damage found in the rabbits. This suggests that the PECE hydrogel may be considered as the novel biomaterial with potential as a sustained release system in glaucoma filtering surgery. Further studies require in shedding the light on the subject
Symmetry breaking and manipulation of nonlinear optical modes in an asymmetric double-channel waveguide
We study light-beam propagation in a nonlinear coupler with an asymmetric
double-channel waveguide and derive various analytical forms of optical modes.
The results show that the symmetry-preserving modes in a symmetric
double-channel waveguide are deformed due to the asymmetry of the two-channel
waveguide, yet such a coupler supports the symmetry-breaking modes. The
dispersion relations reveal that the system with self-focusing nonlinear
response supports the degenerate modes, while for self-defocusingmedium the
degenerate modes do not exist. Furthermore, nonlinear manipulation is
investigated by launching optical modes supported in double-channel waveguide
into a nonlinear uniform medium.Comment: 10 page
Lightweight Structure-aware Transformer Network for VHR Remote Sensing Image Change Detection
Popular Transformer networks have been successfully applied to remote sensing
(RS) image change detection (CD) identifications and achieve better results
than most convolutional neural networks (CNNs), but they still suffer from two
main problems. First, the computational complexity of the Transformer grows
quadratically with the increase of image spatial resolution, which is
unfavorable to very high-resolution (VHR) RS images. Second, these popular
Transformer networks tend to ignore the importance of fine-grained features,
which results in poor edge integrity and internal tightness for largely changed
objects and leads to the loss of small changed objects. To address the above
issues, this Letter proposes a Lightweight Structure-aware Transformer (LSAT)
network for RS image CD. The proposed LSAT has two advantages. First, a
Cross-dimension Interactive Self-attention (CISA) module with linear complexity
is designed to replace the vanilla self-attention in visual Transformer, which
effectively reduces the computational complexity while improving the feature
representation ability of the proposed LSAT. Second, a Structure-aware
Enhancement Module (SAEM) is designed to enhance difference features and edge
detail information, which can achieve double enhancement by difference
refinement and detail aggregation so as to obtain fine-grained features of
bi-temporal RS images. Experimental results show that the proposed LSAT
achieves significant improvement in detection accuracy and offers a better
tradeoff between accuracy and computational costs than most state-of-the-art CD
methods for VHR RS images
Novel Multi-Scale Filter Profile-Based Framework for VHR Remote Sensing Image Classification
Publisher's version (útgefin grein).Filter is a well-known tool for noise reduction of very high spatial resolution (VHR) remote sensing images. However, a single-scale filter usually demonstrates limitations in covering various targets with different sizes and shapes in a given image scene. A novel method called multi-scale filter profile (MFP)-based framework (MFPF) is introduced in this study to improve the classification performance of a remote sensing image of VHR and address the aforementioned problem. First, an adaptive filter is extended with a series of parameters for MFP construction. Then, a layer-stacking technique is used to concatenate the MPFs and all the features into a stacked vector. Afterward, principal component analysis, a classical descending dimension algorithm, is performed on the fused profiles to reduce the redundancy of the stacked vector. Finally, the spatial adaptive region of each filter in the MFPs is used for post-processing of the obtained initial classification map through a supervised classifier. This process aims to revise the initial classification map and generate a final classification map. Experimental results performed on the three real VHR remote sensing images demonstrate the effectiveness of the proposed MFPF in comparison with the state-of-the-art methods. Hard-tuning parameters are unnecessary in the application of the proposed approach. Thus, such a method can be conveniently applied in real applications.This research was funded by the National Science Foundation China (61701396 and 41501378) and the
Natural Science Foundation of Shaan Xi Province (2018JQ4009).Peer Reviewe
MFA-Conformer: Multi-scale Feature Aggregation Conformer for Automatic Speaker Verification
In this paper, we present Multi-scale Feature Aggregation Conformer
(MFA-Conformer), an easy-to-implement, simple but effective backbone for
automatic speaker verification based on the Convolution-augmented Transformer
(Conformer). The architecture of the MFA-Conformer is inspired by recent
state-of-the-art models in speech recognition and speaker verification.
Firstly, we introduce a convolution sub-sampling layer to decrease the
computational cost of the model. Secondly, we adopt Conformer blocks which
combine Transformers and convolution neural networks (CNNs) to capture global
and local features effectively. Finally, the output feature maps from all
Conformer blocks are concatenated to aggregate multi-scale representations
before final pooling. We evaluate the MFA-Conformer on the widely used
benchmarks. The best system obtains 0.64%, 1.29% and 1.63% EER on VoxCeleb1-O,
SITW.Dev, and SITW.Eval set, respectively. MFA-Conformer significantly
outperforms the popular ECAPA-TDNN systems in both recognition performance and
inference speed. Last but not the least, the ablation studies clearly
demonstrate that the combination of global and local feature learning can lead
to robust and accurate speaker embedding extraction. We will release the code
for future works to do comparison.Comment: submitted to INTERSPEECH 202
Spatial–Spectral Feature Fusion Coupled with Multi-Scale Segmentation Voting Decision for Detecting Land Cover Change with VHR Remote Sensing Images
Publisher's version (útgefin grein)In this article, a novel approach for land cover change detection (LCCD) using very high resolution (VHR) remote sensing images based on spatial-spectral feature fusion and multi-scale segmentation voting decision is proposed. Unlike other traditional methods that have used a single feature without post-processing on a raw detection map, the proposed approach uses spatial-spectral features and post-processing strategies to improve detecting accuracies and performance. Our proposed approach involved two stages. First, we explored the spatial features of the VHR remote sensing image to complement the insufficiency of the spectral feature, and then fused the spatial-spectral features with different strategies. Next, the Manhattan distance between the corresponding spatial-spectral feature vectors of the bi-temporal images was employed to measure the change magnitude between the bi-temporal images and generate a change magnitude image (CMI). Second, the use of the Otsu binary threshold algorithm was proposed to divide the CMI into a binary change detection map (BCDM) and a multi-scale segmentation voting decision algorithm to fuse the initial BCDMs as the final change detection map was proposed. Experiments were carried out on three pairs of bi-temporal remote sensing images with VHR remote sensing images. The results were compared with those of the state-of-the-art methods including four popular contextual-based LCCD methods and three post-processing LCCD methods. Experimental comparisons demonstrated that the proposed approach had an advantage over other state-of-the-art techniques in terms of detection accuracies and performance.This research was funded by National Natural Science Foundation of China (Grant Number 41571346
and 61701396), the Natural Science Foundation of Shaan Xi Province (2018JQ4009), and the Open Fund for
Key laboratory of Degraded and Unused Land Consolidation Engineering, the Ministry of Natural Resource
(Grant number SXDJ2017-10 and 2016KCT-23).Peer Reviewe
- …