367 research outputs found
Three dimensional spider-web-like superconducting filamentary paths in single crystals
Since the discovery of high temperature superconductivity in F-doped LaFeAsO,
many new iron based superconductors with different structures have been
fabricated2. The observation of superconductivity at about 32 K in KxFe2-ySe2
with the iso-structure of the FeAs-based 122 superconductors was a surprise and
immediately stimulated the interests because the band structure calculation8
predicted the absence of the hole pocket which was supposed to be necessary for
the theoretical picture of S+- pairing. Soon later, it was found that the
material may separate into the insulating antiferromagnetic K2Fe4Se5 phase and
the superconducting phase. It remains unresolved that how these two phases
coexist and what is the parent phase for superconductivity. In this study we
use different quenching processes to produce the target samples with distinct
microstructures, and apply multiple measuring techniques to reveal a close
relationship between the microstructures and the global appearance of
superconductivity. In addition, we clearly illustrate three dimensional
spider-web-like superconducting filamentary paths, and for the first time
propose that the superconducting phase may originate from a state with one
vacancy in every eight Fe-sites with the root8*root10 parallelogram structure.Comment: 22 pages, 7 figure
Optimization of shift schedule for hybrid electric vehicle with automated manual transmission
Currently, most hybrid electric vehicles (HEVs) equipped with automated mechanical transmission (AMT) are implemented with the conventional two-parameter gear shift schedule based on engineering experience. However, this approach cannot take full advantage of hybrid drives. In other words, the powertrain of an HEV is not able to work at the best fuel-economy points during the whole driving profile. To solve this problem, an optimization method of gear shift schedule for HEVs is proposed based on Dynamic Programming (DP) and a corresponding solving algorithm is also put forward. A gear shift schedule that can be employed in real-vehicle is extracted from the obtained optimal gear shift points by DP approach and is optimized based on analysis of the engineering experience in a typical Chinese urban driving cycle. Compared with the conventional two-parameter gear shift schedule in both simulation and real vehicle experiments, the extracted gear shift schedule is proved to clearly improve the fuel economy of the HEV
Dynamic motion of polar skyrmions in oxide heterostructures
Polar skyrmions have been widely investigated in oxide heterostructure
recently, due to their exotic properties and intriguing physical insights.
Meanwhile, so far, the external field-driven motion of the polar skyrmion, akin
to the magnetic counterpart, has yet to be discovered. Here, using phase-field
simulations, we demonstrate the dynamic motion of the polar skyrmions with
integrated external thermal, electrical, and mechanical stimuli. The external
heating reduces the spontaneous polarization hence the skyrmion motion barrier,
while the skyrmions shrink under the electric field, which could weaken the
lattice pinning and interactions between the skyrmions. The mechanical force
transforms the skyrmions into c-domain in the vicinity of the indenter center
under the electric field, providing the space and driving force needed for the
skyrmions to move. This study confirmed that the skyrmions are quasi-particles
that can move collectively, while also providing concrete guidance for the
further design of polar skyrmion-based electronic devices.Comment: 17 pages, 4 figure
New Dynamic Stability Rig for Tri-sonic Wind-tunnel
AbstractThe present-day unconventional and high-lifting aerospace configuration design has greatly increased the demand for accurate prediction and expanded measure dynamic stability derivatives envelopes of conventional aerospace vehicles. With these issues in mind, china academy of aerospace aerodynamics (CAAA) designed and built a forced oscillation test rig in the sub-, tran- and supersonic wind tunnel that provides new capabilities for aerodynamic researchers to accurately measure the dynamic derivatives and investigate the asymmetric coupling effects of high-lifting aerospace configuration vehicles
GlyphControl: Glyph Conditional Control for Visual Text Generation
Recently, there has been a growing interest in developing diffusion-based
text-to-image generative models capable of generating coherent and well-formed
visual text. In this paper, we propose a novel and efficient approach called
GlyphControl to address this task. Unlike existing methods that rely on
character-aware text encoders like ByT5 and require retraining of text-to-image
models, our approach leverages additional glyph conditional information to
enhance the performance of the off-the-shelf Stable-Diffusion model in
generating accurate visual text. By incorporating glyph instructions, users can
customize the content, location, and size of the generated text according to
their specific requirements. To facilitate further research in visual text
generation, we construct a training benchmark dataset called LAION-Glyph. We
evaluate the effectiveness of our approach by measuring OCR-based metrics and
CLIP scores of the generated visual text. Our empirical evaluations demonstrate
that GlyphControl outperforms the recent DeepFloyd IF approach in terms of OCR
accuracy and CLIP scores, highlighting the efficacy of our method.Comment: Technical report. The codes will be released at
https://github.com/AIGText/GlyphControl-releas
Mask-Attention-Free Transformer for 3D Instance Segmentation
Recently, transformer-based methods have dominated 3D instance segmentation,
where mask attention is commonly involved. Specifically, object queries are
guided by the initial instance masks in the first cross-attention, and then
iteratively refine themselves in a similar manner. However, we observe that the
mask-attention pipeline usually leads to slow convergence due to low-recall
initial instance masks. Therefore, we abandon the mask attention design and
resort to an auxiliary center regression task instead. Through center
regression, we effectively overcome the low-recall issue and perform
cross-attention by imposing positional prior. To reach this goal, we develop a
series of position-aware designs. First, we learn a spatial distribution of 3D
locations as the initial position queries. They spread over the 3D space
densely, and thus can easily capture the objects in a scene with a high recall.
Moreover, we present relative position encoding for the cross-attention and
iterative refinement for more accurate position queries. Experiments show that
our approach converges 4x faster than existing work, sets a new state of the
art on ScanNetv2 3D instance segmentation benchmark, and also demonstrates
superior performance across various datasets. Code and models are available at
https://github.com/dvlab-research/Mask-Attention-Free-Transformer.Comment: Accepted to ICCV 2023. Code and models are available at
https://github.com/dvlab-research/Mask-Attention-Free-Transforme
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