1,485 Hits in 1.4 sec

Object Recognition Based on Amounts of Unlabeled Data [article]

Fuqiang Liu,Fukun Bi,Liang Chen
2016 arXiv   pre-print
Kalal's P-N learning (Kalal et al., 2010; 2012) and Liu's Boost Picking (Fuqiang Liu, 2016) are the theoretical basises of BPT.  ...  In Boost Picking (Fuqiang Liu, 2016) , two weak classifiers pick out the false positives and false negatives from the outputs of f just like what P-N experts do.  ... 
arXiv:1603.07957v1 fatcat:tgcijabsmrcxdi4rsknmanbkzy

Low Threshold Plasmonic Nanolaser Based on Graphene

Litu Xu, Fang Li, Shuai Liu, Fuqiang Yao, Yahui Liu
2018 Applied Sciences  
A hybrid plasmonic nanolaser based on nanowire/air slot/semicircular graphene and metal wire structure was designed. In this structure, the waveguides in the nanowires and the graphene-metal interface are coupled to form a hybrid plasma mode, which effectively reduces the metal loss. The mode and strong coupling of the laser are analyzed by using the finite-element method. Its electric field distribution, propagation loss, normalized mode area, quality factor, and lasing threshold are studied
more » ... th the different geometric model. Simulation results reveal that the performance of the laser using this structure can be optimized by adjusting the model parameters. Under the optimal parameters, the effective propagation loss is only 0.0096, and the lasing threshold can be as low as 0.14 μm−1. This structure can achieve deep sub-wavelength confinement and low-loss transmission, and provides technical support for the miniaturization and integration of nano-devices.
doi:10.3390/app8112186 fatcat:2vcdzrlsfvhmfii44zjqvvajem

Spatially Focused Attack against Spatiotemporal Graph Neural Networks [article]

Fuqiang Liu, Luis Miranda-Moreno, Lijun Sun
2021 arXiv   pre-print
Spatiotemporal forecasting plays an essential role in various applications in intelligent transportation systems (ITS), such as route planning, navigation, and traffic control and management. Deep Spatiotemporal graph neural networks (GNNs), which capture both spatial and temporal patterns, have achieved great success in traffic forecasting applications. Understanding how GNNs-based forecasting work and the vulnerability and robustness of these models becomes critical to real-world
more » ... For example, if spatiotemporal GNNs are vulnerable in real-world traffic prediction applications, a hacker can easily manipulate the results and cause serious traffic congestion and even a city-scale breakdown. However, despite that recent studies have demonstrated that deep neural networks (DNNs) are vulnerable to carefully designed perturbations in multiple domains like objection classification and graph representation, current adversarial works cannot be directly applied to spatiotemporal forecasting due to the causal nature and spatiotemporal mechanisms in forecasting models. To fill this gap, in this paper we design Spatially Focused Attack (SFA) to break spatiotemporal GNNs by attacking a single vertex. To achieve this, we first propose the inverse estimation to address the causality issue; then, we apply genetic algorithms with a universal attack method as the evaluation function to locate the weakest vertex; finally, perturbations are generated by solving an inverse estimation-based optimization problem. We conduct experiments on real-world traffic data and our results show that perturbations in one vertex designed by SA can be diffused into a large part of the graph.
arXiv:2109.04608v1 fatcat:c6jliz44fnaxhh77qk3acb3kbm

Surface Plasmon Nanolaser: Principle, Structure, Characteristics and Applications

Litu Xu, Fang Li, Yahui Liu, Fuqiang Yao, Shuai Liu
2019 Applied Sciences  
Photonic devices are becoming more and more miniaturized and highly integrated with the advancement of micro-nano technology and the rapid development of integrated optics. Traditional semiconductor lasers have diffraction limit due to the feedback from the optical system, and their cavity length is more than half of the emission wavelength, so it is difficult to achieve miniaturization. Nanolasers based on surface plasmons can break through the diffraction limit and achieve deep sub-wavelength
more » ... or even nano-scale laser emission. The improvement of modern nanomaterial preparation processes and the gradual maturity of micro-nano machining technology have also provided technical conditions for the development of sub-wavelength and nano-scale lasers. This paper describes the basic principles of surface plasmons and nano-resonators. The structure and characteristics of several kinds of plasmonic nanolasers are discussed. Finally, the paper looks forward to the application and development trend of nanolasers.
doi:10.3390/app9050861 fatcat:h4dn74s7yzc2ljh3ujwvkqpej4

Doped, conductive SiO2 nanoparticles for large microwave absorption

Michael Green, Zhanqiang Liu, Peng Xiang, Yan Liu, Minjie Zhou, Xinyu Tan, Fuqiang Huang, Lei Liu, Xiaobo Chen
2018 Light: Science & Applications  
Although many materials have been studied for the purpose of microwave absorption, SiO2 has never been reported as a good candidate. In this study, we present for the first time that doped, microwave conductive SiO2 nanoparticles can possess an excellent microwave absorbing performance. A large microwave reflection loss (RL) of -55.09 dB can be obtained. The large microwave absorption originates mainly from electrical relaxation rather than the magnetic relaxation of the incoming microwave
more » ... . The electrical relaxation is attributed to a large electrical conductivity that is enabled by the incorporation of heterogeneous (N, C and Cl) atoms. The removal of the magnetic susceptibility only results in a negligible influence of the microwave absorption. In contrast, the removal of the heterogeneous atoms leads to a large decrease in the electrical conductivity and microwave absorption performance. Meanwhile, the microwave absorption characteristics can be largely adjusted with a change of the thickness, which provides large flexibility for various microwave absorption applications.
doi:10.1038/s41377-018-0088-8 pmid:30455870 pmcid:PMC6234207 fatcat:4zg66pzlg5cktkczyil2kzxpaa

Polarized Self-Attention: Towards High-quality Pixel-wise Regression [article]

Huajun Liu, Fuqiang Liu, Xinyi Fan, Dong Huang
2021 arXiv   pre-print
Pixel-wise regression is probably the most common problem in fine-grained computer vision tasks, such as estimating keypoint heatmaps and segmentation masks. These regression problems are very challenging particularly because they require, at low computation overheads, modeling long-range dependencies on high-resolution inputs/outputs to estimate the highly nonlinear pixel-wise semantics. While attention mechanisms in Deep Convolutional Neural Networks(DCNNs) has become popular for boosting
more » ... -range dependencies, element-specific attention, such as Nonlocal blocks, is highly complex and noise-sensitive to learn, and most of simplified attention hybrids try to reach the best compromise among multiple types of tasks. In this paper, we present the Polarized Self-Attention(PSA) block that incorporates two critical designs towards high-quality pixel-wise regression: (1) Polarized filtering: keeping high internal resolution in both channel and spatial attention computation while completely collapsing input tensors along their counterpart dimensions. (2) Enhancement: composing non-linearity that directly fits the output distribution of typical fine-grained regression, such as the 2D Gaussian distribution (keypoint heatmaps), or the 2D Binormial distribution (binary segmentation masks). PSA appears to have exhausted the representation capacity within its channel-only and spatial-only branches, such that there is only marginal metric differences between its sequential and parallel layouts. Experimental results show that PSA boosts standard baselines by 2-4 points, and boosts state-of-the-arts by 1-2 points on 2D pose estimation and semantic segmentation benchmarks.
arXiv:2107.00782v2 fatcat:yjeby42o5bcjrnctyi36jqqrge

Eccentricity is not the only source of elliptic flow fluctuations [article]

Kai Xiao, Feng Liu, Fuqiang Wang
2013 arXiv   pre-print
Sources of event-by-event elliptic flow fluctuations in relativistic heavy-ion collisions are investigated in a multiphase transport model. Besides the well-known initial eccentricity fluctuations, several other sources of dynamical fluctuations are identified. One is fluctuations in initial parton configurations at a given eccentricity. Second is quantum fluctuations in parton interactions during system evolution. Third is fluctuations caused by hadronization and final-state hadronic
more » ... s. The magnitudes of these fluctuations are investigated relative to eccentricity fluctuations and average flow magnitude. The fluctuations from the latter two sources are found to be negative. The results may have important implications to the interpretation of elliptic flow data.
arXiv:1307.6661v1 fatcat:jonumydf6bdermxf7bsggpt5ya

Mechanism Reduction and Bunsen Burner Flame Verification of Methane

Haitao Lu, Fuqiang Liu, Yulan Wang, Xiongjie Fan, Jinhu Yang, Cunxi Liu, Gang Xu
2018 Energies  
Based on directed relation graph with error propagation methods, 39 species and 231 reactions skeletal mechanism were obtained from Mech_56.54 (113 species and 710 reactions) mechanism of methane. The ignition delay times, laminar flame propagation speed, and important species were calculated using the simplified mechanism at different pressures and equivalence ratios. The simulation results were in good agreement with that of detailed mechanisms and experimental data. The numerical simulation
more » ... f the Bunsen burner jet flame was carried out using the simplified methane mechanism, and the simulation results well reproduced the temperature, flow fields and distribution of important species at flame zone. The compact methane reduced mechanism can not only correctly respond to its dynamic characteristics, but also can be well used for numerical simulation, which is of great significance in engineering applications.
doi:10.3390/en12010097 fatcat:rlivne35tzaf3djrc7stfqyuay

Large chest keloids treatment with expanded parasternal intercostal perforator flap

Hao Liu, Fuqiang Sui, Shu Liu, Kexin Song, Yan Hao, Youbin Wang
2021 BMC Surgery  
These can be removed Open Access *Correspondence: † Hao Liu and Fuqiang Sui contributed equally to this article 1 Department of Plastic Surgery, Peking Union Medical College Hospital, Beijing  ... 
doi:10.1186/s12893-021-01116-3 pmid:33743633 fatcat:2svvvwgwjzd5rk7a77cu6x7pou

Superconductivity in layered iron Selenide induced by cobalt- and sodium-doping [article]

Zhanqiang Liu, Aihua Fang, Fuqiang Huang, Mianheng Jiang
2008 arXiv   pre-print
Corresponding author: Fuqiang Huang: Tel.: +86 21 52411620; fax: +86 21 52413903  ... 
arXiv:0808.1784v1 fatcat:zbt22egeundsvdzb4xpmszhd5u

Nanodroplets impact on surfaces decorated with ridges

Hanyi Liu, Fuqiang Chu, Jun Zhang, Dongsheng Wen
2020 Physical Review Fluids  
Liu et al.  ...  [23] studied large droplets impacting on a small wire, while Liu et al.  ... 
doi:10.1103/physrevfluids.5.074201 fatcat:a74bxvb5fjastfdavfplqwgppi

Ecohydrological Separation Hypothesis: Review and Prospect

Yaping Liu, Yongchen Fang, Hongchang Hu, Fuqiang Tian, Zhiqiang Dong, Mohd Yawar Ali Khan
2020 Water  
The ecohydrological-separation (ES) hypothesis is that the water used for plant transpiration and the water used for streams and groundwater recharge comes from distinct subsurface compartmentalized pools. The ES hypothesis was first proposed in a study conducted in the Mediterranean climate region, based on the stable isotope method in 2010. To date, the ES hypothesis has proven to be widespread around the world. The ES hypothesis is a new understanding of the soil water movement process,
more » ... is different from the assumption that only one soil reservoir in the traditional hydrology. It is helpful to clear the water sources of plants and establish a new model of the ecohydrological process. However, the theoretical basis and mechanism of the ES hypothesis are still unclear. Therefore, we analyzed the characteristics of ES phenomenon in different climatic regions, summarized the research methods used for the ES hypothesis, concluded the definitions of tightly bound water and mobile water, discussed the mechanism of isotopic differences of different reservoirs and their impacts on ES evaluation and pointed out the existing problems of the ES hypothesis. Future research should focus on the following three aspects: (a) detailed analysis of ES phenomenon characteristics of different plant species in different climatic regions; (b) further understanding of the ES phenomenon mechanism; c) improvement of the experimental methods.
doi:10.3390/w12082077 fatcat:iyuhp6ifaratnbcnkebw7xjomq

Research progress of asymptomatic bacteriuria before arthroplasty

Qingyu Zhang, Lihua Liu, Wei Sun, Fuqiang Gao, Liming Cheng, Zirong Li
2018 Medicine  
Zhang QY et al. Research progress of asymptomatic bacteriuria before arthroplasty: a systematic review.
doi:10.1097/md.0000000000009810 pmid:29443741 pmcid:PMC5839824 fatcat:jiljzdryybbipmcowwilkrt54u

Microfluidic Platforms for Gradient Generation and its Applications

Chunfei Hu, Jingjing Liu, Hongmei Chen, Fuqiang Nie
2017 Biochemistry & Analytical Biochemistry  
Ye N, Qin J, Liu X, Shi W, Lin B (2007) Characterizing doxorubicininduced apoptosis in HepG2 cells using an integrated microfluidic device.  ...  Ye N, Qin J, Shi W, Liu X, Lin B (2007) Cell-based high content screening using an integrated microfluidic device. Lab Chip 7: 1696-1704. 55.  ... 
doi:10.4172/2161-1009.1000320 fatcat:lxdhxssyonff3b7kbbyl4nf6v4

A VTA GABAergic neural circuit mediates visually evoked innate defensive responses [article]

Zheng Zhou, Xuemei Liu, Shanping Chen, Zhijian Zhang, Yu-anming Liu, Quentin Montardy, Yongqiang Tang, Pengfei Wei, Nan Liu, Lei Li, Xiaobin He, Chen Chen (+4 others)
2018 bioRxiv   pre-print
SUMMARYInnate defensive responses are essential for animal survival and are conserved across species. The ventral tegmental area (VTA) plays important roles in learned appetitive and aversive behaviors, but whether it plays a role in mediating or modulating innate defensive responses is currently unknown. We report that GABAergic neurons in the mouse VTA (VTAGABA+) are preferentially activated compared to VTA dopaminergic (VTADA+) neurons when a threatening visual stimulus evokes innate
more » ... e behavior. Functional manipulation of these neurons showed that activation of VTAGABA+ neurons is indispensable for looming-evoked defensive flight behavior and photoactivation of these neurons is sufficient for looming-evoked defensive-like flight behavior, whereas no such role can be attributed for VTADA+ neurons. Viral tracing and in vivo and in vitro electrophysiological recordings showed that VTAGABA+ neurons receive direct excitatory inputs from the superior colliculus (SC). Furthermore, we showed that glutamatergic SC-VTA projections synapse onto VTAGABA+ neurons that project to the central nucleus of the amygdala (CeA) and that the CeA is involved in mediating the defensive behavior. Our findings demonstrate that visual information about aerial threats access to the VTAGABA+ neurons mediating innate behavioral responses, suggesting a more general role for the VTA.
doi:10.1101/493007 fatcat:lujrk4mcubegjkdnlf5tawtmk4
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