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| 1 | High-fidelity,low-latency polarization quantum state transmissions over a hollow-core conjoined-tube fiber at around 800 nm显示文摘Hollow-core fiber(HCF)promises to unify air-borne light propagation and non-line-of-sight transmission,thus holding great potential for versatile photonics-based quantum information applications.The early version of HCF based on photonic-bandgap guidance has not proven itself a reliable quantum channel because of the poor modal purity in both spatial and polarization domains,as well as significant difficulty in fabrication when the wavelength shifts to the visible region.In this work,based on the polarization degree of freedom,we demonstrate high-fidelity(∼0.98)single-photon transmission and distribution of entangled photons over a 36.4 m hollow-core conjoined-tube fiber(CTF)by using commercial silicon single-photon avalanche photodiodes.Our CTF realizes the combined merits of low loss,high spatial modal purity,low polarization degradation,and low chromatic dispersion.We also demonstrate single-photon low-latency(∼99.96%speed of light in vacuum)transmission,paving the way for extensive uses of HCF links in versatile photonics-based quantum information processing. | Xinyu Chen Wei Ding Ying-Ying Wang Shou-Fei Gao Feixiang Xu Huichao Xu Yi-Feng Hong Yi-Zhi Sun Pu Wang Yan-Qing Lu Lijian Zhang | 2021 | Photonics Research2021，9，4： | 1 |
| 2 | An enhanced spectral diversity coregistration method for dualpolarimetric Sentinel-1A/B TOPS data显示文摘Sentinel-1A/B data are crucial for retrieving numerical information about surface phenomena and processes.Coregistration of terrain observation by progressive scans(TOPS)data is a critical step in its application.TOPS data must be fundamentally co-registered with an accuracy of 0.001 pixels.However,various decorrelation factors due to natural vegetation and seasonal effects affect the coregistration accuracy of TOPS data.This paper proposed an enhanced spectral diversity coregistration method for dual-polarimetric(PolESD)Sentinel-1A/B TOPS data.The PolESD method suppresses speckle noise based on a unified non-local framework in dual-pol Synthetic Aperture Radar(SAR),and extracts the phase of the optimal polarization channel from the denoised polarimetric interferometric coherency matrix.Compared with the traditional ESD method developed for single-polarization data,the PolESD method can obtain more accurate coherence and phase and get more pixels for azimuth-offset estimation.In bare areas covered with low vegetation,the number of pixels selected by PolESD is more than the Boxcar method.It can also correct misregistration more effectively and eliminate phase jumps in the burst edge.Therefore,PolESD will help improve the application of TOPS data in low-coherence scenarios. | Nan Fang Xingjun Luo Peng Shen Lei Xie Guoming Liu Feixiang Wei Kun Jiang Wenbin Xu | 2023 | Geodesy and Geodynamics2023，14，5： | 0 |
| 3 | The value of ultrasound elastography in differential diagnosisof superficial lymph nodes显示文摘The study evaluated the value of ultrasound elastography in differentiating the benign and malignant superficial lymph nodes.A total of 112 subjects,including 82 patients with enlarged lymph nodes and 30 healthy volunteers,were recruited.All the subjects were examined by B-mode ultrasonography,power Doppler ultrasonogra-phy and elastography.Most of the patients were histo-pathologically confirmed by needle aspiration cytology and some patients were diagnosed by clinical data combined with follow-upfindings.The sensitivity,speci-ficity and accuracy of B-mode ultrasonography were 59.8%,76.5%and 67.1%,those of the bloodflow classification by power Doppler ultrasonography 77.0%,82.3%and 79.4%and those of elastographic classification 74.7%,97.1%and 84.5%,respectively.The elasticity of the lymph nodes was quantitatively measured and defined as stiffness value.When the stiffness value of 2.395 was taken as the cutoff point,the sensitivity and specificity of elastography were 78.41%and 98.51%,and the Youden index reached the highest,with the value being 0.7692.The stiffness values of two indeterminate benign lymph nodes,the elastrographicfindings of which were rated as patterns 2 and 3,were below the cutoff point.The elastographicfindings of 10 malignant lymph nodes were also classified as pattern 2 or 3.Only one of them had the stiffness values below the cutoff point.It was concluded that ultrasound elastography is a novel,noninvasive and convenient tool for the differentiation of the nature of the superficial lymph nodes in clinical practice. | Yanrong ZHANG Qing LV Yehua YIN Mingxing XIE Feixiang XIANG Chengfa LU Tianwei YAN Wei LI Hui XU Yan HUANG | 2009 | Frontiers of Medicine2009，3，3： | 0 |
| 4 | Design and implementation of a nonlinear robust controller based on the disturbance observer for the active spray boom suspension显示文摘Spray boom vibrations are one of the main causes of the uneven distribution of agrochemicals.Using active suspension to maintain the correct height of nozzles is critical for obtaining a uniform spray pattern and minimizing the possibility of spray drift.However,the electro-hydraulic active pendulum boom suspension has nonlinear uncertain factors such as parameter uncertainties,external disturbances,model error,etc.,which complicate the design of the controller.Therefore,this paper proposes a nonlinear robust feedback control method with disturbances compensation,which integrates a robust controller and disturbance observers through the backstepping method.Initially,to verify the performance of the controller,the Lyapunov stability theory is used to prove that the proposed controller can guarantee the given transient performance and the final tracking accuracy.Furthermore,taking the active suspension of a 28 m wide boom driven by a single-rod hydraulic actuator as an implementation case,the proposed NRCDC controller was compared with a variety of control schemes through a rapid control prototype of a pendulum active suspension.Finally,the proposed control scheme is implemented on a self-propelled sprayer with a boom of 12 m in length.The field test results show that all the performance indicators of the NRCDC controller are better than the other three conventional controllers.Both laboratory and field tests have verified the effectiveness and high performance of the proposed controller. | Longfei Cui Xinyu Xue Wei Kong Suming Ding Wei Gu Feixiang Le | 2023 | International Journal of Agricultural and Biological Engineering2023，16，1： | 0 |
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