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Combining sum-difference and auxiliary beams for adaptive monopulse in jamming

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Journal of Systems Engineering and Electronics 2013年第3期24卷 372-381页

作者： rongfeng li Can Rao lingyan Dai Yongliang Wang Key Research Lab Air Force Early Warning Academy

Only in the presence of sidelobe jamming （SLJ）, can the conventional adaptive monopulse technique null the jamming effectively and maintain the monopulse angle estimation accuracy simultaneously. While mainlobe jamming （MLJ） exists, the mainlobe of adaptive pattern will subject to serious distortion, which results in a failure of detecting and tracking targets by monopulse technique. Therefore, a monopulse angle estimation algorithm based on combining sum-difference beam and auxiliary beam is presented. This algorithm utilizes both high gain difference beams and high gain auxiliary beams for cancelling the mainlobe jammer and multiple sidelobe jammers （SLJs） while keeping an adap- tive monopulse ratio. Theoretical analysis and simulation results indicate that the serious invalidation of monopulse technique in MLJ and SLJs scenarios is resolved well, which improves the monopulse angle accuracy greatly. Furthermore, the proposed algorithm is of simple implementation and low computational complexity.

关键词： adaptive beamforming auxiliary beam mainlobe jam- ming monopulse estimation.

Summertime Subtropical Countercurrent on isopycnals in the western North Pacific

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Chinese Science Bulletin 2002年第9期47卷 786-789页

作者： li rongfeng YOU Xiaobao P.Chu LASG Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Department of Oceanography Naval Postgraduate SchoolMontereyCA93943USA

Circulations on isopycnals (σθ) in the western North Pacific were investigated by using P-vector method; the data were taken from the U.S. Navy’s climatological temperature and salinity dataset (public domain) with 1/2°×1/2° resolution. Results not only show the main circulation systems on isopycnals in the western North Pacific such as the North Equatorial Current (NEC), Kuroshio and Ku-roshio Countercurrent, but also reveal the Subtropical Countercurrent (STCC) clearly. In this note we pay attention to discussing the distribution of STCC in summer (in June). The STCC flows eastward along a winding road; on shallow isopycnals, the STCC originates from the area east of Bashi Strait at about 122.5°E; with the isopycnals increasing, the origin and flow core of STCC move to north and east, but the main part of STCC is still between 18?and 23.5°N, i.e. near the Tropic of Cancer. There exists STCC on all isopycnals between the sea surface and 25.8σθ.The current vectors of STCC on isopycnals are

关键词： P-vector method isopycnals Subtropical Countercur-rent.

Recent progress on biodegradable materials and transient electronics

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Bioactive Materials 2018年第3期3卷 322-333页

作者： rongfeng li liu Wang Deying Kong Lan Yin School of Materials Science and Engineering Tsinghua UniversityBeijing 100084 China

Transient electronics(or biodegradable electronics)is an emerging technology whose key characteristic is an ability to dissolve,resorb,or physically disappear in physiological environments in a controlled *** applications include eco-friendly sensors,temporary biomedical implants,and datasecure *** electronics built with water-soluble,biocompatible active and passive materials can provide multifunctional operations for diagnostic and therapeutic purposes,such as monitoring intracranial pressure,identifying neural networks,assisting wound healing process,*** review summarizes the up-to-date materials strategies,manufacturing schemes,and device layouts for biodegradable electronics,and the outlook is discussed at the *** is expected that the translation of these materials and technologies into clinical settings could potentially provide vital tools that are beneficial for human healthcare.

关键词： Biodegradable electronics Transient electronics Biodegradable materials Silicon Metals

Adaptive detectors in the Krylov subspace

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Science China(Information Sciences) 2014年第10期57卷 117-127页

作者： liU WeiJian XIE WenChong li rongfeng WANG ZeTao WANG Yongliang College of Electronic Science and Engineering National University of Defense Technology Key Research Lab Wuhan Radar Academy

The validity of the application of the Krylov subspace techniques in adaptive filtering and detection is investigated. A new verification of the equivalence of two well-known methods in the Krylov subspace, namely the multistage Wiener filters(MWF) and the auxiliary-vector filtering(AVF), is given in this paper. The MWF and AVF are incorporated into two well-known detectors, namely, the adaptive matched filter(AMF) and Kelly’s generalized likelihood ratio test(GLRT) including their diagonally loaded versions, which form new *** to the conventional AMF, GLRT, and their diagonally loaded versions as well as the reduced-rank AMF and GLRT, the probabilities of detection(PDs) of the new detectors are improved especially when the sample support is low. More importantly, the new detectors are robust of the rank selection of the clutter subspace compared to the reduced-rank AMF and GLRT. These new detectors all possess asymptotic constant false alarm rate(CFAR) property.

关键词： adaptive matched filter(AMF) auxiliary-vector filtering(AVF) diagonal loading generalized likelihood ratio test(GLRT) Krylov subspace multistage Wiener filters(MWF)

Adaptive detection in the presence of signal mismatch

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Journal of Systems Engineering and Electronics 2015年第1期26卷 38-43页

作者： Weijian liu Wenchong Xie rongfeng li Fei Gao Xiaoqin Hu Yongliang Wang College of Electronic Science and Engineering National University of Defense Technology Air Force Early Warning Academy

The problem of adaptive detection in the situation of signal mismatch is considered; that is, the actual signal steering vector is not aligned with the nominal one. Two novel tunable detectors are proposed. They can control the degree to which the mismatched signals are rejected. Remarkably, it is found that they both cover existing famous detectors as their special cases. More importantly, they possess the constant false alarm rate（CFAR）property and achieve enhanced mismatched signal rejection or improved robustness than their natural competitors. Besides, they can provide slightly better matched signals detection performance than the existing detectors.

关键词： mismatched signal detection adaptive coherence estimator(ACE) adaptive matched filter(AMF) generalized likelihood ratio test(GLRT) tunable detector

A Doubly Parameterized Detector for Mismatched Signals

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Chinese Journal of Electronics 2015年第1期24卷 152-156页

作者： liU Weijian XIE Wenchong ZHANG Qianping li rongfeng DUAN Keqing WANG Yongliang College of Electronic Science and Engineering National University of Defense Technology Key Research Laboratory Air Force Early Warning Academy College of Computer Science and Technology Wuhan University of Technology

In this paper, we consider the problem of adaptive multichannel signal detection in the presence of signal mismatch, and introduce a novel tunable detector,which is parameterized by two tunable parameters. It has the Constant false alarm rate(CFAR) property and covers Kelly’s generalized likelihood ratio test(KGLRT), Adaptive matched filter(AMF), and Adaptive coherence estimator(ACE) as its three special cases. The novel detector controls the mismatched signal by adjusting two tunable parameters. Remarkably, it can achieve improved detection performance for matched signals, enhanced rejection of seriously mismatched signals, and better robustness to slightly mismatched signals than its natural competitors.

关键词： Constant false alarm rate(CFAR) Mismatched signal Multichannel signal Tunable detector.

Argo floats revealing bimodality of large-scale mid-depth circulation in the North Atlantic

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Acta Oceanologica Sinica 2008年第2期27卷 1-10页

作者： CHU Peter C IVANOV Leonid M MELNICHENKO Oleg V li rongfeng Department of Oceanography Naval Postgraduate School Monterey California USA International Pacific Research Center University of Hawaii at Manoa Hawaii USA Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

Analysis of Argo float trajectories at 1 000 m and temperature at 950 m in the North Atlantic between November 2003 and January 2005 demonstrates the existence of two different circulation modes with fast transition between them. Each mode has a pair of cyclonic - anticyclonic gyres. The difference is the location of the cyclonic gyre. The cyclonic gyre stretches from southeast to northwest in the first mode and from the southwest to the northeast in the second mode. The observed modes strongly affect the heat and salt transport in the North Atlantic. In particular, the second mode slows down the westward transport of the warm and saline water from the Mediterranean Sea.

关键词： Argo trajectory data Atlantic Ocean biomodality mid-depth circulation optimal spectral decomposition

Dendrimers as carriers for contrast agents in magnetic resonance imaging

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Chinese Science Bulletin 2010年第27期55卷 3085-3093页

作者： YAN GuoPing AI ChaoWu li liang ZONG rongfeng liU Fan School of Material Science and Engineering Wuhan Institute of Technology Wuhan 430074 China

Magnetic resonance imaging (MRI) is a non-invasive clinical imaging modality,which has become widely used in the diagnosis of human diseases around the *** MRI exams include the use of contrast *** goal of an ideal MRI contrast agent involves the tissue-or organ-targeting materials with high relaxivity and specificity,low toxicity and side effects,suitable long intravascular duration and excretion time and high contrast enhancement with low doses,in vivo,all coupled to low overall *** are synthetic,highly branched,mono-disperse macromolecules of nanometer *** associated with these dendrimers such as uniform size,water solubility,modifiable surface functionality and available internal cavities make them candidates for ideal carriers of MRI contrast *** research progress of the dendritic contrast agents is discussed.

关键词：磁共振造影剂磁共振成像树枝状载体 MRI造影剂持续时间临床检查人类疾病

Isolation and identifi cation of antimicrobial metabolites from sea anemone-derived fungus Emericella ***01

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Journal of Oceanology and limnology 2021年第3期39卷 1010-1019页

作者： Yang YUE Huahua YU rongfeng li linfeng HU Song liU Rong’e XING Pengcheng li Key Laboratory of Experimental Marine Biology Center for Ocean Mega-ScienceInstitute of OceanologyChinese Academy of SciencesQingdao 266071China Laboratory for Marine Drugs and Bioproducts Pilot Qingdao National Laboratory for Marine Science and TechnologyQingdao 266237China School of Chemistry and Chemical Engineering Henan Institute of Science and TechnologyXinxiang 453003China

Marine symbiotic fungi represent an intriguing source of discovery of novel secondary metabolites with various biological *** anemones are benthic marine invertebrates,however,the cultivable symbiotic fungi residing in the sea anemones are paid few attentions compared to those derived from their cnidarian *** we show the identification of antimicrobial secondary metabolites from the sea anemone-derived symbiotic *** offive isolated fungal strains,only the strain SMA01 showed strong antimicrobial activities,which was assigned into the genus Emericella based on the morphological characteristics and the ITS *** swift from liquid fermentation to solid rice medium presented little influence on its antibacterial activity.A chemical investigation of the ethyl acetate extract of the Emericella ***01 led to discovery of the primary antibiotic metabolite phenazine-1-carboxylic *** IC_(50) values of the phenazine-1-carboxylic acid against Phytophthora capsici,Gibberella zeae,and Verticillium dahliae were determined to be 23.26-53.89μg/*** the best of our knowledge,this was the first report of Emericella *** sea *** current study may benefit understanding of the defensive chemical interactions between the symbiotic fungi and their host sea anemones.

关键词： sea anemone symbiotic fungi phenazine-1-carboxylic acid antimicrobial activity