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Classification of birds and drones by exploiting periodical motions in Doppler spectrum series

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Journal of Systems Engineering and Electronics 2023年第1期34卷 19-27页

作者： DUAN Jia ZHANG Lei wu Yifeng ZHANG Yue ZHAO Zeya GUO Xinrong School of Electronics and Communication Sun Yat-Sen UniversityShenzhen 518107China Beijing Institute of Tracking and Telecommunication Technology Beijing 100854China Armed Police Engineering University Xi’an 510507China

With the rapidly growing abuse of drones, monitoring and classification of birds and drones have become a crucial safety issue. With similar low radar cross sections(RCSs), velocities, and heights, drones are usually difficult to be distinguished from birds in radar measurements. In this paper, we propose to exploit different periodical motions of birds and drones from highresolution Doppler spectrum sequences(DSSs) for classification.This paper presents an elaborate feature vector representing the periodic fluctuations of RCS and micro kinematics. Fed by the Doppler spectrum and feature sequence, the long to short-time memory(LSTM) is used to solve the time series classification.Different classification schemes to exploit the Doppler spectrum series are validated and compared by extensive real-data experiments, which confirms the effectiveness and superiorities of the proposed algorithm.

关键词： target classification long-to-short memory(LSTM) drone discrimination Doppler spectrum series

Nickel/Quinim Enabled Asymmetric Carbamoyl-Acylation of Unactivated Alkenes

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中国化学:英文版 2023年第14期41卷 1673-1678页

作者： Xianqing wu Haiyan Li Feng He Jingping Qu yifeng Chen Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering Feringa Nobel Prize Scientist Joint Research CenterFrontiers Science Center for Materiobiology and Dynamic ChemistrySchool of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai200237 China

Transition metal-catalyzed difunctionalization of tethered alkene has emerged as a prevailing tool for the expedient construction of synthetically valuable cyclic compounds.However,most efforts have been devoted to the reaction of styrene-type substrates due to their rigid scaffold and high reactivity.With respect to the difunctionalization of nonaromatic tethered olefin,especially the mono-substituted alkene,still remains largely underdeveloped.Herein,we disclose a nickel/Quinim complex and TBADT-cocatalyzed asymmetric carbamoyl-acylation of unactivated alkene tethered on nonaromatic carbamoyl chlorides with diverse aldehydes.The reaction exhibits broad substrate scope with good functional group tolerance,as well as high reaction efficiency and enantioselectivity.Both monosubstituted and 1,1-substituted alkenes can work well with either aliphatic or aromatic aldehydes under the current protocol,providing convenient access to an array of medicinally useful chiralγ-lactams derivatives bearing a convertible acyl functionality.This reaction showcases more application possibilities of the chiral Quinim ligand in the future asymmetric catalytic transformations.

关键词： Nickel Quinim ligand Lactams Asymmetric catalysis Alkenes

Influence of soil to structure stiffness on the accuracy of the pushover method for underground structures

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Earthquake Research Advances 2022年第4期2卷 22-27页

作者： Qi wu yifeng Zhou Jiawei Jiang wuxi Institute of Technology Wuxi214021China Institute of Geotechnical Engineering Nanjing Tech UniversityNanjing210009China

The pushover method for underground structures is a seismic analysis method featured by high calculation accuracy and a simple implementation process.The method has been widely used in seismic design and other related scientific research;however,the influence of different soil-structure flexibility ratios on the accuracy of this method is still not well understood.In this study,we select the cross-section structures beneath the Daikai subway station as the research object and establish 12 finite element analysis models with different soil-structure flexibility ratios using ABAQUS.All models are computed by the dynamic time-history method or the pushover method.Furthermore,the dynamic time-history solution result is taken as the standard solution,and the precision and application of the pushover analysis method are discussed based on the parameters of peak interlayer displacement and peak internal force of the middle column section.The results show that the soil-structure flexibility ratio has a significant influence on the calculation accuracy of the pushover method,and the calculation accuracy of this method is the most ideal when the soil-structure flexibility is equal to 1.The research results can provide significant references for the seismic design of underground structures or the improvement of simplified seismic analysis methods.

关键词： Underground structure Pushover Soil to structure flexibility Accuracy

Nickel-Catalyzed Regiodivergent Acylzincation of Styrenes with Organozincs and CO

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Chinese Journal of Chemistry 2024年第6期42卷 599-604页

作者： Chenglong Wang Ning Liu Xianqing wu Jingping Qu yifeng Chen Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering Feringa Nobel Prize Scientist Joint Research CenterFrontiers Science Center for Materiobiology and Dynamic ChemistrySchool of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai200237 China Dedicated to the Special Issue of C1 Chemistry.

Transition metal-catalyzed carbometallation of unsaturated hydrocarbons constitutes one of the most efficient synthetic methodologies for the construction of C—C bond.Recently,the incorporation of organometallic reagent with the CO gas as a nucleophilic acyl synthon could enable the acylmetallation reaction,which greatly increases the horizon of carbometallation chemistry.Herein,we report a nickel-catalyzed regiodivergent acylzincation of o-cyano cinnamate ester and o-cyano styrene,in which the cyano moiety intramolecularly captures zinc intermediates to trigger the tandem cyclization process.This protocol features mild conditions,broad substrate scope and excellent functional group tolerance,thus affording a diverse array of highly functionalized carbocyclic compounds.

关键词： Carbonylation Carbometallation Styrene Nickel Cyclization

Application of a p-version curved C^(1)finite element based on the nonlocal Kirchhoff plate theory to the vibration analysis of irregularly shaped nanoplates

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Science China(Technological Sciences) 2023年第10期66卷 3025-3047页

作者： XIANG Wei NI Hua TIAN yifeng wu Yang LIU Bo School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China Technology and Equipment of Rail Transit Operation and Maintenance Key Laboratory of Sichuan Province Chengdu 610031China Southwest China Research Institute of Electronic Equipment Chengdu 610036China CAEP Software Center for High Performance Numerical Simulation Beijing 100088China Institute of Applied Physics and Computational Mathematics Beijing 100088China The Solid Mechanics Research Centre Beihang University(BUAA)Beijing 100191China

Nanoplates have been widely used as elementary components for ultrasensitive and ultrafine resolution applications in the field of nano-electro-mechanical systems because of their potentially remarkable mechanical properties.The accurate analysis of their mechanical behavior is currently of particular interest in the function design and reliability analysis of nano-scaled devices.To examine the size-dependent bending and vibration behavior of nanoplates with curvilinear and irregular shapes,a new p-version curved C^(1)finite element is formulated in the framework of the nonlocal Kirchhoff plate model.This newly developed element not only enables an accurate geometry representation and easy mesh generation of curvilinear domains but also overcomes the difficulty of imposing C^(1)conformity required by the nonlocal Kirchhoff plate model,particularly on the curvilinear inter-element boundaries.Numerical examples show that this element can produce an exponential rate of convergence even when curved elements are used in the domain discretization.Vast numerical results are presented for nanoplates with various geometric shapes,including rectangular,circular,elliptic,annular,and sectorial.The high accuracy of the present element is verified by comparing the obtained results with analytical and numerical results in the literature.Additionally,a comprehensive parametric analysis is conducted to investigate the influences of nonlocal parameters,plate dimensions,and boundary conditions on the nonlocal behavior of nanoplates.The present element can be envisaged to allow large-scale mechanical simulations of nanoplates,with a guarantee of accuracy and efficiency.

关键词： nanoplates nonlocal theory p-version finite element method C^(1)conformity irregular shape

Consensus disturbance rejection control of directed multi-agent networks with extended state observer

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Chinese Journal of Aeronautics 2020年第5期33卷 1486-1493页

作者： Shaopan GUO Zhongkui LI yifeng NIU Lizhen wu State Key Laboratory for Turbulence Complex System Department of Mechanics and Aerospace EngineeringPeking UniversityBeijing 100871China College of Intelligence Science and Technology National University of Defense TechnologyChangsha 410073China

This paper investigates the consensus disturbance rejection problem among multiple high-order agents with directed graphs.Based on disturbance observers,distributed consensus disturbance rejection protocols are constructed in leaderless and leader-follower consensus setups.Different from the previous related papers,the consensus protocols in this paper are developed in a fully distributed fashion,relying on only the state information of each agent and its neighbors.Sufficient conditions are provided to guarantee that the asymptotic stability of high-order multi-agent systems can be reached with matched disturbances.

关键词： Adaptive control Consensus control Distributed control Disturbance rejection Multi-agent systems

Theory of property rights： comparing Marx with Coase

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Social Sciences in China 2008年第2期29卷 5-17页

作者： wu Yifeng School of Economics Renmin University of China

马克思用崭新的无产阶级世界观构建了产权理论大厦的主体工程。产权是所有制的法律形态。作为财产形式的法权关系，产权不但是反映经济关系的意志关系，而且是历史的产物和历史的范畴，具有历史的形式。马克思着重研究了资本主义的财产... 详细信息

马克思用崭新的无产阶级世界观构建了产权理论大厦的主体工程。产权是所有制的法律形态。作为财产形式的法权关系，产权不但是反映经济关系的意志关系，而且是历史的产物和历史的范畴，具有历史的形式。马克思着重研究了资本主义的财产关系，即在揭示经济领域中资本和雇佣劳动之间对立关系的基础上，将价值增值过程表述为法学和产权理论中的所有权关系及其占有过程，涉及所有权、占有权、使用权、支配权、经营权、索取权、继承权等一系列权力的统一与分离，从而论证了资本主义财产关系和产权制度的阶级对抗性质。马克思揭示的从“消极扬弃”到“积极扬弃”的变革方向，把资本主义生产关系及其产权制度将被公有制的经济关系和法权关系所代替这一历史必然性和长期发展趋势清晰地呈现出来。

关键词：马克思科斯产权理论产权制度

Modulation of ionic arrangement in polar magnet by chemical pressure

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Chinese Chemical Letters 2023年第3期34卷 502-506页

作者： Shuang Zhao Jinjin Yang yifeng Han Meixia wu Man-Rong Li Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education School of ChemistrySun Yat-sen UniversityGuangzhou 510006China Institute of Semiconductors Guangdong Academy of SciencesGuangzhou 510650China

The similarity of local structure-connection pattern and volumetrically compressive strain between host and guest phases can be used to stabilize heteroid metastable matter and tune the local structure and properties.Here a series of metastable ABO_(3)(A=Mn;B=Mn_(0.5)Mo_(0.5),Mn_(1/3)Ta_(2/3),and Mn_(0.5)Ta_(0.5)) were trapped in LiTaO_(3) to form solid-solutions,where the difference of solid solubility limit reveals the barrier of size effect on chemical pressure.All samples show antiferromagnetic characters,in which the(LiTaO_(3))_(1-x)-[Mn(Mn_(0.5)Mo_(0.5))O_(3)]_(x) series exhibit more complex magnetic and dielectric behaviors with the increasing of metastable guest phase,stemming from the complex interactive mechanism between Mn^(2+)and Mo^(6+).The cell parameter variation of (LiTaO_(3))_(1-z)-[Mn(Mn_(0.5)Ta_(0.5))O_(3)]_zshows a more regularly changing tendency,on account of the smallest size barrier.These findings show that chemical pressure can effectively stimulate the physical pressure to intercept and modulate a metastable phase at atomic-scale by compressibility effect between like structures at ambient pressure.

关键词： Chemical pressure Trapping metastable-phase Cationic arrangement Antiferromagnetism Dielectricity

Ten-year emission characteristics of atmospheric pollutants from incineration of sacrificial offerings in China

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Journal of Environmental Sciences 2022年第4期34卷 391-400页

作者： Yangyang Cui Gen Zhang Wei Wang Yan Shen Xiaoman Zhai Xuefang wu Renfei Li Bobo wu yifeng Xue National Engineering Research Center of Urban Environmental Pollution Control Beijing Municipal Research Institute of Environmental ProtectionBeijing 100037China State Key Laboratory of Severe Weather&Key Laboratory for Atmospheric Chemistry of CMA Institute of Atmospheric CompositionChinese Academy of Meteorological SciencesBeijing 100081China Key Laboratory of Pollution Control of Ministry of Civil Affairs 101 Institute of Ministry of Civil AffairsBeijing 100070China Beijing Technology and Business University Beijing 100048China

The incineration of sacrificial offerings is a significant widely practiced custom that is also a kind of neglected air pollution source in China.Our results showed that the emission factors of particulate matter,SO_(2),CO,NO_(x),and VOCs emitted from the incineration of sacrificial offerings with purification systems were reduced by 95%,19%,9%,82%,and 42%,respectively,compared with those without a purification system,revealing a significant effect of the flue gas purification system on reducing particulate matter and gaseous pollutants.The emission level of air pollutants from the incineration of sacrificial offerings remained stable before 2013 and then showed a remarkable decrease after the implementation of China′s Air Pollution Prevention Action Plan in 2013.The emissions of TSP(total suspended particulate),PM_(10),PM_(2.5),and NO_(x)in 2009 were 8222,6106,5656 and 15,878 ton,respectively,obviously higher than 3434,2551,2305 and 8579 ton in 2019.Such trend was affected by both the quantity of incineration and the installation rate of purification systems after the Emission Standard of Air Pollutants for Crematory(GB 13801-2015)issued in China.Distinct spatial distribution of atmospheric pollutants from incineration of sacrificial offerings was found with higher in the east and south of China than the west and north of China,which is proportional to the regional economy and population.The maximum ground-level concentration typically occurred at 0.12-0.2 km from the pollution source,posing potential health risks to people entering and exiting funeral and burial sites and nearby residents.

关键词： Incineration of sacrificial offerings Atmospheric pollutants Purification system Emission inventory