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Metasurface Photodetectors

Jinzhao Li, Junyu Li, Shudao Zhou, Fei Yi
2021 Micromachines  
Metamaterial Perfect Absorber (MPA) Schottky Photodetector Li et al. proposed a strategy to enhance the photoresponsivity of Schottky photodetector using MPA (Figure 6e ).  ...  To detect circularly polarized light, Li et al. designed a chiral metamaterial, consisting of a periodic array of 'Z'-shaped silver (Ag) antennas on top of a PMMA spacer and an optically thick Ag backplate  ... 
doi:10.3390/mi12121584 pmid:34945434 pmcid:PMC8704368 fatcat:jyxhyarsnbakzix2ss75cbz4ru

Studying murine hindlimb ischemia by photoacoustic microscopy

Shuoqi Ye Shuoqi Ye, Junyu Yang Junyu Yang, Jianzhong Xi Jianzhong Xi, Qiushi Ren Qiushi Ren, Changhui Li Changhui Li
2012 Chinese Optics Letters (COL)  
The murine model of hindlimb ischemia is extensively used in studies on the physiology and pathology of ischemia and angiogenesis. Traditional non-invasive evaluation methods, such as laser or ultrasound blood flow perfusion imaging and micro-CT angiography, are limited either by low resolution or toxic exogenous agents. Relying on intrinsic high optical absorption contrast, we conduct label-free imaging of subcutaneous blood vasculature in the hindlimb of murine models by photoacoustic
more » ... py (PAM). The angiogenesis induced by ischemia in the hindlimb is successfully observed at high resolution in vivo and non-invasively. PAM is a potentially powerful imaging method for studying ischemic diseases and resultant angiogenesis.
doi:10.3788/col201210.121701 fatcat:e6rg4fhqpfc3dfdcxqbq2uipem

Multimodal Gait Recognition for Neurodegenerative Diseases [article]

Aite Zhao, Jianbo Li, Junyu Dong, Lin Qi, Qianni Zhang, Ning Li, Xin Wang, Huiyu Zhou
2021 arXiv   pre-print
In recent years, single modality based gait recognition has been extensively explored in the analysis of medical images or other sensory data, and it is recognised that each of the established approaches has different strengths and weaknesses. As an important motor symptom, gait disturbance is usually used for diagnosis and evaluation of diseases; moreover, the use of multi-modality analysis of the patient's walking pattern compensates for the one-sidedness of single modality gait recognition
more » ... thods that only learn gait changes in a single measurement dimension. The fusion of multiple measurement resources has demonstrated promising performance in the identification of gait patterns associated with individual diseases. In this paper, as a useful tool, we propose a novel hybrid model to learn the gait differences between three neurodegenerative diseases, between patients with different severity levels of Parkinson's disease and between healthy individuals and patients, by fusing and aggregating data from multiple sensors. A spatial feature extractor (SFE) is applied to generating representative features of images or signals. In order to capture temporal information from the two modality data, a new correlative memory neural network (CorrMNN) architecture is designed for extracting temporal features. Afterwards, we embed a multi-switch discriminator to associate the observations with individual state estimations. Compared with several state-of-the-art techniques, our proposed framework shows more accurate classification results.
arXiv:2101.02469v1 fatcat:uwwkfomhkfbaljyv4ftngusk7e

On static and hydrodynamic biaxial nematic liquid crystals [article]

Junyu Lin, Yimei Li, Changyou Wang
2020 arXiv   pre-print
In the first part of this paper, we will consider minimizing configurations of the Oseen-Frank energy functional E(n, m) for a biaxial nematics (n, m):Ω→S^2×S^2 with n· m=0 in dimension three, and establish that it is smooth off a closed set of 1-dimension Hausdorff measure zero. In the second part, we will consider a simplified Ericksen-Leslie system for biaxial nematics (n, m) in a two dimensional domain and establish the existence of a unique global weak solution (u, n, m) that is smooth off
more » ... at most finitely many singular times for any initial and boundary data of finite energy. They extend to biaxial nematics of earlier results corresponding to minimizing uniaxial nematics by Hardt-Kindelerherer-Lin and a simplified hydrodynamics of uniaxial liquid crystal by Lin-Lin-Wang respectively.
arXiv:2006.04207v1 fatcat:pzbmvxvesbd33ex3nq5gzzgy6i

LSTM for diagnosis of neurodegenerative diseases using gait data

Aite Zhao, Junyu Dong, Jie Li, Lin Qi, Hui Yu, Hui Yu, Junyu Dong
2018 Ninth International Conference on Graphic and Image Processing (ICGIP 2017)  
Li et al. adopted the SVM and NB methods to support the classification of different NDs (ALS, PD, HD), which made a concrete analysis of the gait data measured by accelerometers [3] .  ... 
doi:10.1117/12.2305277 fatcat:rxkffefnazez5ecp6nvrkfxyqi

Congested Crowd Instance Localization with Dilated Convolutional Swin Transformer [article]

Junyu Gao, Maoguo Gong, Xuelong Li
2021 arXiv   pre-print
Li et al. [33] design a contextbased module in face detector and propose a data augmentation strategy (Data-anchor-sampling) to prompt the performance. Deng et al.  ... 
arXiv:2108.00584v1 fatcat:plf7prb2lng2fpmhzplomjqce4

Limitation of SDMA in Ultra-Dense Small Cell Networks [article]

Junyu Liu, Min Sheng, Jiandong Li
2017 arXiv   pre-print
Benefitting from multi-user gain brought by multi-antenna techniques, space division multiple access (SDMA) is capable of significantly enhancing spatial throughput (ST) in wireless networks. Nevertheless, we show in this letter that, even when SDMA is applied, ST would diminish to be zero in ultra-dense networks (UDN), where small cell base stations (BSs) are fully densified. More importantly, we compare the performance of SDMA, single-user beamforming (SU-BF) (one user is served in each cell)
more » ... and full SDMA (the number of served users equals the number of equipped antennas). Surprisingly, it is shown that SU-BF achieves the highest ST and critical density, beyond which ST starts to degrade, in UDN. The results in this work could shed light on the fundamental limitation of SDMA in UDN.
arXiv:1801.00222v1 fatcat:zhdeb3odx5hkjkdt2c3gpq525e

Early stages of nucleation and growth in melt crystallized polyethylene

Junyu Li, Wei Li, He Cheng, Lina Zhang, Yang Li, Charles C. Han
2012 Polymer  
Time-resolved synchrotron small angle X-ray scattering (SAXS) was used to investigate the early stages of crystallization in melt crystallized polyethylene. Classic Gibbs nucleation or density fluctuation theory can be used to describe the primary nucleation mechanism. At 110 C, no signal of crystallization can be detected by SAXS for 30 min. When it is lower than 110 C, the low q scattering intensity (0.008 < q < 0.03 Å À1 ) begins to upturn, and the primary nucleation process starts. The
more » ... red fractal dimension of the critical nuclei is in the vicinity of 3 which is close to the prediction of classic Gibbs nucleation theory. The growth rate of density fluctuations R(q) at different scattering vector q for different temperatures was obtained by analyzing the increase of scattering intensities. The results show that the growth rate of density fluctuation gets much bigger with the decrease of the isothermal crystallization temperature, but there is no signal of spinodal decomposition mechanism, in which there should be a linear relationship between R(q)/q 2 and q 2 .
doi:10.1016/j.polymer.2012.03.054 fatcat:iw2bmmyz3nhezaunsmkoik4d7e

Characterization and compression of dissipative-soliton-resonance pulses in fiber lasers [article]

Daojing Li, Lei Li, Junyu Zhou, Luming Zhao, Dingyuan Tang, Deyuan Shen
2016 arXiv   pre-print
We report numerical and experimental studies of dissipative-soliton-resonance (DSR) in a fiber laser with a nonlinear optical loop mirror. The DSR pulse presents temporally a flat-top profile and a clamped peak power. Its spectrum has a rectangle profile with characteristic steep edges. It shows a unique behavior as pulse energy increases: The rectangle part of the spectrum is unchanged while the newly emerging spectrum sits on the center part and forms a peak. Experimental observations match
more » ... ll with the numerical results. Moreover, compression of the DSR pulses is both numerically and experimentally demonstrated for the first time. An experimentally obtained DSR pulse of 63 ps duration is compressed down to 760 fs, with low-intensity pedestals using a grating pair. Before being compressed to its narrowest width, the pulse firstly evolves into a cat-ear profile, and the corresponding autocorrelation trace shows a crown shape, which distinguishes itself from properties of other solitons formed in fiber lasers.
arXiv:1601.05601v1 fatcat:oxtovaeysvdfdbkiut7oopasre

The mechanism of Li deposition on the Cu substrates in the anode-free Li metal batteries [article]

Genming Lai, Junyu Jiao, Chi Fang, Liyuan Sheng, Yao Jiang, Chuying Ouyang, Jiaxin Zheng
2022 arXiv   pre-print
The results show that the Li layers on the Cu (100), Cu (110), and Cu (111) surfaces are closer to the structures of Li (110), Li (100), and Li (110) surfaces, respectively.  ...  Due to the rapid growth in the demand for high-energy-density Li batteries and insufficient global Li reserves, the anode-free Li metal batteries are receiving increasing attention.  ...  Li (110), Li (100), and Li (110) surfaces, respectively.  ... 
arXiv:2208.04089v1 fatcat:lplkmms6urcd3oavb4ltwmzhbm

Associated Spatio-Temporal Capsule Network for Gait Recognition [article]

Aite Zhao, Junyu Dong, Jianbo Li, Lin Qi, Huiyu Zhou
2021 arXiv   pre-print
(Corresponding author: Jianbo Li.)  ...  Zhao and Jianbo Li are with College of Computer Science and Technology, Qingdao University, China. E-mail: zhaoaite@qdu.edu.cn; li-jianbo@qdu.edu.cn.  ... 
arXiv:2101.02458v1 fatcat:rr7fnv3okrc5thxmsqtdwoly3i

Multi-level Similarity Learning for Low-Shot Recognition [article]

Hongwei Xv, Xin Sun, Junyu Dong, Shu Zhang, Qiong Li
2019 arXiv   pre-print
To acquire the object-level area, Li et al. [21] proposed a zoom network which utilized the candidate region to crop the original images. Wei et al.  ... 
arXiv:1912.06418v1 fatcat:vivmcpoq4fhqrdixwykq66jq6a

Prediction stability as a criterion in active learning [article]

Junyu Liu, Xiang Li, Jin Wang, Jiqiang Zhou, Jianxiong Shen
2019 arXiv   pre-print
The * Junyu Liu performed this work while at Hikvision Research Institude. basic ideas include using confidence, max-entropy [7] , mutual information [8] , mean standard deviation [9] or variationratio  ... 
arXiv:1910.12246v1 fatcat:q6ixl3xvavdozomhkmvv6gbwl4

PyramidBox++: High Performance Detector for Finding Tiny Face [article]

Zhihang Li, Xu Tang, Junyu Han, Jingtuo Liu, Ran He
2019 arXiv   pre-print
With the rapid development of deep convolutional neural network, face detection has made great progress in recent years. WIDER FACE dataset, as a main benchmark, contributes greatly to this area. A large amount of methods have been put forward where PyramidBox designs an effective data augmentation strategy (Data-anchor-sampling) and context-based module for face detector. In this report, we improve each part to further boost the performance, including Balanced-data-anchor-sampling,
more » ... Anchors and Dense Context Module. Specifically, Balanced-data-anchor-sampling obtains more uniform sampling of faces with different sizes. Dual-PyramidAnchors facilitate feature learning by introducing progressive anchor loss. Dense Context Module with dense connection not only enlarges receptive filed, but also passes information efficiently. Integrating these techniques, PyramidBox++ is constructed and achieves state-of-the-art performance in hard set.
arXiv:1904.00386v1 fatcat:k7tkzef4knctbdu3x2bjy53uma

Enhancing the Transferability via Feature-Momentum Adversarial Attack [article]

Xianglong and Yuezun Li and Haipeng Qu and Junyu Dong
2022 arXiv   pre-print
Transferable adversarial attack has drawn increasing attention due to their practical threaten to real-world applications. In particular, the feature-level adversarial attack is one recent branch that can enhance the transferability via disturbing the intermediate features. The existing methods usually create a guidance map for features, where the value indicates the importance of the corresponding feature element and then employs an iterative algorithm to disrupt the features accordingly.
more » ... er, the guidance map is fixed in existing methods, which can not consistently reflect the behavior of networks as the image is changed during iteration. In this paper, we describe a new method called Feature-Momentum Adversarial Attack (FMAA) to further improve transferability. The key idea of our method is that we estimate a guidance map dynamically at each iteration using momentum to effectively disturb the category-relevant features. Extensive experiments demonstrate that our method significantly outperforms other state-of-the-art methods by a large margin on different target models.
arXiv:2204.10606v1 fatcat:c3wimzbe5zcilnwidrh65sljqi
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