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FrFT-CSWSF: Estimating cross-range velocities of ground moving targets using multistatic synthetic aperture radar

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Chinese Journal of Aeronautics 2014年第5期27卷 1223-1232页

作者： li chenlei liu Mei Zhao Bowen Zhang Lei School of Electronics and Information Engineering Harbin Institute of Technology

Estimating cross-range velocity is a challenging task for space-borne synthetic aperture radar（SAR）, which is important for ground moving target indication（GMTI）. Because the velocity of a target is very small compared with that of the satellite, it is difficult to correctly estimate it using a conventional monostatic platform algorithm. To overcome this problem, a novel method employing multistatic SAR is presented in this letter. The proposed hybrid method, which is based on an extended space-time model（ESTIM） of the azimuth signal, has two steps： first, a set of finite impulse response（FIR） filter banks based on a fractional Fourier transform（FrFT） is used to separate multiple targets within a range gate; second, a cross-correlation spectrum weighted subspace fitting（CSWSF） algorithm is applied to each of the separated signals in order to estimate their respective parameters. As verified through computer simulation with the constellations of Cartwheel, Pendulum and Helix, this proposed time-frequency-subspace method effectively improves the estimation precision of the cross-range velocities of multiple targets.

关键词： Filter banks Fractional Fourier transform Ground moving target indication Parameter estimation Subspace methods Synthetic aperture radar

Silicon-based on-chip hybrid(de)multiplexers

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Science China(Information Sciences) 2018年第8期61卷 90-103页

作者： chenlei li Hao WU Ying TAN Shipeng WANG Daoxin DAI Centre for Optical and Electromagnetic Research State Key Laboratory for Modern Optical InstrumentationCollege of Optical Science and Engineering Zhejiang University

A review is given on the recent progress of silicon-based on-chip hybrid multiplexers, which are the key elements to enable more than one(de)multiplexing techniques simultaneously, including wavelengthdivision-multiplexing(WDM), polarization-division-multiplexing(PDM), and mode-division-multiplexing(MDM). This helps enhance the link capacity of optical interconnects multiplexed with many *** first part gives a review on the recent developed silicon-based hybrid WDM-PDM(de)multiplexers enabling WDM and PDM simultaneously, which helps achieve 2 N channels by introducing N wavelengths and dual polarizations. The recent progress of silicon-based hybrid WDM-MDM(de)multiplexers developed is reviewed in the second part. With the hybrid WDM-MDM(de)multiplexers, one can achieve N × M channels by using N wavelengths and M guided-modes. Finally, the silicon-based hybrid MDM-PDM(de)multiplexers are presented as the key to enhance the link capacity for a single wavelength carrier.

关键词： silicon photonics (de)multiplexing wavelength mode polarization waveguide

Confined synthesis of MoS_(2) with rich co-doped edges for enhanced hydrogen evolution performance

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Journal of Energy Chemistry 2022年第7期31卷 18-26,I0002页

作者： Zongge li chenlei li Jianwen Chen Xu Xing Yaqun Wang Ying Zhang Miaosen Yang Guoxin Zhang Al-ion Battery Research Center Department of Energy Storage TechnologyShandong University of Science and TechnologyQingdao 266590ShandongChina State Key Laboratory of Heavy Oil Processing China University of Petroleum(East China)Qingdao 266580ShandongChina School of Chemical Engineering Northeast Electric Power UniversityJilin 132012JilinChina

Activating MoS_(2) with atomic metal doping is promising to harvest desirable Pt-matched hydrogen evolution reaction(HER)catalytic ***,we developed an efficient method to access edgerich lattice-distorted MoS_(2) for highly efficient HER via in-situ sulphuration of atomic Co/Mo species that were well-dispersed in a formamide-derived N-doped carbonaceous(f-NC)*** from others,pre-embedding Co/Mo species in f-NC controls the release of metal sources upon annealing in S vapor,grafting the as-made MoS_(2) with merits of short-range crystallinity,distorted lattices,rich defects,and more edges *** content of atomic Co species embedded in MoS_(2) reaches up to 2.85 at.%,and its atomic dispersion has been systematically confirmed by using XRD,HRTEM,XPS,and XAS *** Co-doped MoS_(2) sample exhibits excellent HER activity,achieving overpotentials of 67 and155 m V at j=10 m A cm^(-2) in 1.0 M KOH and 0.5 M H_(2)SO_(4),*** functional theory simulations suggest that,compared with free-doping MoS_(2),the edged Co doping is responsible for the significantly improved HER *** method,in addition to providing reliable Pt-matched HER catalysts,may also inspire the general synthesis of edge-rich metal-doped metal chalcogenide for a wide range of energy conversion applications.

关键词： Molybdenum sulfide Metal doping Formamide Carbon material Hydrogen evolution reaction

Technical challenges for high-frequency wireless communication

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Journal of Communications and Information Networks 2016年第2期1卷 19-28页

作者： ZHAO Jianping li chenlei li Xianghua SHEN Long Huawei Technologies Co. Ltd.Shanghai 201206China

Recent rapid developments in 4G wireless communication have been motivated by breakthroughs in air interface technology,exemplified by the replacement of WCDMA(Wideband Code Division Multiple Access)with OFDM(Orthogonal Frequency-division Multiplexing).Although the protocol to adopt for 5G HF(High-Frequency)wireless communication-including such matters as waveform,network deployment,and frequency range-has been a controversial issue for a number of years,a common view is that there is a large gap between the rapidly increasing requirements pertaining to traffic capacity and the capabilities of current LTE(Long Term Evolution)networks in terms of spectral and power efficiency.A number of technical challenges need to be overcome in order to bridge this *** this paper,by briefly reviewing progress in HF technology,we summarize technical challenges ranging from propagation attenuation and the implementation of circuit devices,to signal processing and the Ka-band to offer feasible reflection on the forthcoming technological revolution.

关键词： high frequency 5G LTE Ka-band

Subwavelength silicon photonics for onchip mode-manipulation

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PhotoniX 2021年第1期2卷 297-331页

作者： chenlei li Ming Zhang Hongnan Xu Ying Tan Yaocheng Shi Daoxin Dai Centre for Optical and Electromagnetic Research State Key Laboratory for Modern Optical InstrumentationZhejiang Provincial Key Laboratory for Sensing TechnologiesInternational Research Center for Advanced PhotonicsCollege of Optical Science and EngineeringZhejiang UniversityHangzhou 310058China Ningbo Research Institute Zhejiang UniversityNingbo 315100China

On-chip mode-manipulation is one of the most important physical fundamentals for many photonic integrated devices and *** the past years,great progresses have been achieved on subwavelength silicon photonics for on-chip modemanipulation by introducing special subwavelength photonic *** them,there are two popular waveguide structures *** is silicon hybrid plasmonic waveguides(HPWGs)and the other one is silicon subwavelengthstructured waveguides(SSWGs).In this paper,we focus on subwavelength silicon photonic devices and the applications with the manipulation of the effective indices,the modal field profiles,the mode dispersion,as well as the ***,a review is given about subwavelength silicon photonics for the fundamental-mode manipulation,including high-performance polarization-handling devices,efficient mode converters for chip-fiber edge-coupling,and ultra-broadband power ***,a review is given about subwavelength silicon photonics for the higherorder-mode manipulation,including multimode converters,multimode waveguide bends,and multimode waveguide ***,some emerging applications of subwavelength silicon photonics for on-chip mode-manipulation are discussed.

关键词： Subwavelength Silicon photonics Mode manipulation Polarization Multimode Waveguide

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硅基纳米光子集成回路中的模式转换与耦合

激光与光电子学进展 2017年第5期54卷 34-49页

作者：李晨蕾戴道锌浙江大学光电科学与技术学院光及电磁波研究中心浙江杭州310058

硅纳米光波导具有超高折射率差与超小横截面,因而具有超强光场限制能力,为实现超高集成度纳米光子回路提供了一种极具吸引力的途径。众所周知,在光子集成回路中,模式转换与耦合是实现各种功能器件的重要基础。对硅光子集成回路中的模式... 详细信息

硅纳米光波导具有超高折射率差与超小横截面,因而具有超强光场限制能力,为实现超高集成度纳米光子回路提供了一种极具吸引力的途径。众所周知,在光子集成回路中,模式转换与耦合是实现各种功能器件的重要基础。对硅光子集成回路中的模式转换与耦合原理、新结构与新器件进行了详细分析和讨论。研究了硅纳米光波导锥形结构中模式传输及演化过程,揭示了其特有的偏振相关模式转换机制。结果表明,当光波导横截面存在不对称性时,可能在某些特定波导宽度范围内产生偏振模杂化,为实现偏振旋转提供了一种方便的方法。通过调控非对称定向耦合结构中模式转换与耦合的相位匹配条件,为实现超小型偏振分束器、大带宽模式复用-解复用器等关键器件提供重要途径。

关键词：集成光学硅纳米光波导模式耦合模式转换偏振复用

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智慧古籍图书馆的环境监测系统

图书馆论坛 2020年第2期40卷 107-112页

作者：李琛磊种兰祥西北大学现代教育技术中心西北大学信息科学与技术学院

针对智慧古籍图书馆环境监测系统多停留在理论研究阶段,缺乏将新技术应用到实践的问题,设计一种基于物联网结构的多点无线传输环境监测系统。选用能联接多种传感器的电子原型开发系统Arduino作为测量节点,具有嵌入式芯片设计的片式计算... 详细信息

针对智慧古籍图书馆环境监测系统多停留在理论研究阶段,缺乏将新技术应用到实践的问题,设计一种基于物联网结构的多点无线传输环境监测系统。选用能联接多种传感器的电子原型开发系统Arduino作为测量节点,具有嵌入式芯片设计的片式计算机Raspberry PI作为网关兼轻量级Web服务器,结合具有跳频功能的nRF24L01无线射频模块,组成星型网络拓扑的无线监测系统。同时网关并行连接到OneNet物联网平台,用户可在任意地点查看智慧古籍图书馆环境情况。实验测试表明,该系统性能优良、扩展性强、用户体验好,价格低廉、部署方便,具有较高的应用价值。

关键词：智慧古籍图书馆物联网树莓派无线射频通信数据可视化

国际研发联盟网络结构对企业创新绩效的影响研究——基于社会资本视角

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科学学与科学技术管理 2017年第1期38卷 52-61页

作者：李晨蕾柳卸林朱丽中国科学院大学经济与管理学院北京100190 中国科学院大学中国丹麦科研教育中心北京100190

以国际研发联盟中的中国企业为研究对象,运用社会网络分析法构建联盟网络。在社会资本理论视角下,从结构、关系、认知3个维度,实证研究结构洞、网络紧密程度两大网络结构特征对创新绩效的影响以及认知的共同性和关系强度对结构特征的调... 详细信息

以国际研发联盟中的中国企业为研究对象,运用社会网络分析法构建联盟网络。在社会资本理论视角下,从结构、关系、认知3个维度,实证研究结构洞、网络紧密程度两大网络结构特征对创新绩效的影响以及认知的共同性和关系强度对结构特征的调节作用。最终得出结论,结构洞与创新绩效负相关,共同认知削弱了这一负向作用;网络紧密程度与创新绩效正相关,共同认知增强了这一正向作用;而关系强度的调节作用不显著。

关键词：国际研发联盟网络结构社会资本理论创新绩效

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加拿大通讯安全局通讯元数据搜集问题研究

情报杂志 2018年第9期37卷 154-159,126页

作者：吴常青李晨蕾天津商业大学法学院天津300134 天津铁路运输检察院天津300142

[目的/意义]"斯诺登事件"后加拿大通讯安全局涉及加拿大人通讯元数据搜集项目引致社会各界对其会不当干涉加拿大人隐私权的担忧。该问题研究对于探索通讯元数据搜集制度如何在维护国家安全和公民隐私权保障之间取得平衡有着重要的理论... 详细信息

[目的/意义]"斯诺登事件"后加拿大通讯安全局涉及加拿大人通讯元数据搜集项目引致社会各界对其会不当干涉加拿大人隐私权的担忧。该问题研究对于探索通讯元数据搜集制度如何在维护国家安全和公民隐私权保障之间取得平衡有着重要的理论意义。[方法/过程]通过理论思辨的方法分析加拿大通讯安全局通讯元数据搜集的主体、类型、授权和监督,通过经验分析方法研究通讯元数据搜集的实践状况。[结果/结论]研究表明,加拿大政府虽认为通讯安全局通讯元数据搜集项目符合法律和政策,但大数据时代通讯安全局搜集通讯元数据是否干预加拿大人隐私权、该活动是否得到有效监督等问题却引起广泛的争论。

关键词：加拿大通讯安全局通讯元数据元数据搜集隐私权