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开拓性课题的探索与形成

科技导报 1986年第1期 38-41页

作者：吴建民田纳西大学宇航研究院戈沙特(Goethert)讲座教授北京航空学院名誉教授

本文是根据吴建民教授1985年5月应邀回国讲学时在北京航空学院所作报告的录音整理的。经本人审阅后同意在本刊发表。两个值得注意的倾向我几次访问中国,觉得在中国的研究工作中,有两个值得注意的倾向: 1.从事验证性研究工作的多。许多... 详细信息

本文是根据吴建民教授1985年5月应邀回国讲学时在北京航空学院所作报告的录音整理的。经本人审阅后同意在本刊发表。两个值得注意的倾向我几次访问中国,觉得在中国的研究工作中,有两个值得注意的倾向: 1.从事验证性研究工作的多。许多研究人员正在进行的所谓'课题研究'

关键词：优先次序课题物理概念开拓性

Convexification of Hybrid AC-DC Optimal Power Flow with Line-Commutated Converters

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CSEE journal of Power and Energy Systems 2024年第2期10卷 617-628页

作者： Hongyuan Liang Zhigang Li j.H.Zheng Q.H.wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China

Line-commutated converter (LCC)-based high-voltage DC (HVDC) systems have been integrated with bulk AC power grids for interregional transmission of renewable power. The nonlinear LCC model brings additional nonconvexity to optimal power flow (OPF) of hybrid AC-DC power grids. A convexification method for the LCC station model could address such nonconvexity but has rarely been discussed. We devise an equivalent reformulation for classical LCC station models that facilitates second-order cone convex relaxation for the OPF of LCC-based AC-DC power grids. We also propose sufficient conditions for exactness of convex relaxation with its proof. Equivalence of the proposed LCC station models and properties, exactness, and effectiveness of convex relaxation are verified using four numerical simulations. Simulation results demonstrate a globally optimal solution of the original OPF can be efficiently obtained from relaxed model.

关键词： AC-DC power system convex relaxation linecommutated converter optimal power flow second-order cone programming

Attitude control of multi-spacecraft systems on SO(3)with stochastic links failure

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Chinese journal of Aeronautics 2024年第3期37卷 320-331页

作者： KANG Zeyu SHEN Qiang wu Shufan Chris j.DAmAREN mU Zhongcheng School of Aeronautics and Astronautics Shanghai Jiao Tong UniversityShanghai 200240China Institute for Aerospace Studies University of TorontoTorontoOntario M3H 5T6Canada

In this paper,for multi-Spacecraft System(mSS)with a directed communication topology link and a static virtual leader,a controller is proposed to realize attitude consensus and attitude stabilization with stochastic links failure and actuator ***,an mSS attitude error model suitable for a directed topology link and with a static virtual leader based on SO(3)is derived,which considers that the attitude error on SO(3)cannot be defined based on algebraic ***,we design a controller to realize the mSS on SO(3)with attitude consensus and attitude stabilization under stochastic links failure and actuator ***,the simulation results of a multi-spacecraft system with stochastic links failure and a static virtual leader spacecraft are demonstrated to illustrate the efficiency of the attitude controller.

关键词： multi-spacecraft systems Attitude consensus Attitude stabilization Stochastic links failure Super-martingale convergence

Emerging high-entropy strategy: A booster to the development of cathode materials for power batteries

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journal of Advanced Ceramics 2024年第8期13卷 1093-1118页

作者： Liping Huang jinging Zhu j-Xuan Liu Houzheng wu Guo-jun Zhang State Key Laboratory for modification of Chemical Fibers and Polymer materials Institute of Functional MaterialsCollege of Materials Science and EngineeringDonghua UniversityShanghai 201620China SIAmC Advanced materials Cooperation Huzhou 313100China

The coordinated development of new energy vehicles and the energy storage industry has become essential for reducing carbon *** cathode material is the key material that determines the energy density and cost of a power battery,but currently developed and applied cathode materials cannot meet the requirements for high specific capacity,low cost,safety,and good ***-entropy materials(HEms)are a new type of single-phase material composed of multiple principal elements in equimolar or near-equimolar *** interaction between multiple elements can play an important role in improving the comprehensive properties of the material,which is expected to solve the limitations of battery materials in practical ***,this review provides a comprehensive overview of the current development status and modification strategies of power batteries(lithium-ion batteries(LiBs)and sodium-ion batteries(SIBs)),proposes a high-entropy design strategy,and analyses the structure-activity relationship between the high-entropy effects and battery ***,future research topics related to high-entropy cathode materials,including computational guide design,specific synthesis methods,high-entropy electrochemistry,and high-throughput databases,are *** review aims to provide practical guidance for the development of high-entropy cathode materials for next-generation power batteries.

关键词： cathode materials lithium-ion battery(LIB) sodium-ion battery(SIB) high-entropy strategy

Semitransparent organic solar cells with high light utilization efficiency and color rendering index

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Science China Chemistry 2024年第7期67卷 2248-2256页

作者： Ni Gao Haijun Bin Shangrong wu RenéA.j.janssen Yongfang Li Laboratory of Advanced Optoelectronic materials Suzhou Key Laboratory of Novel Semiconductor Materials and DevicesCollege of ChemistryChemical Engineering and Materials ScienceSoochow UniversitySuzhou 215123China jiangsu Key Laboratory of Advanced Negative Carbon Technologies Soochow UniversitySuzhou 215123China molecular materials and Nanosystems&Institute for Complex molecular Systems Eindhoven University of TechnologyEindhoven 5600 MBthe Netherlands

Semitransparent organic solar cells(ST-OSCs)have garnered considerable attention as promising renewable energy technology for integrating photovoltaics into ***,there is a trade-off between power conversion efficiency(PCE)and average visible transmittance(AVT),which hinders the achievement of a high light utilization efficiency(LUE).In this study,we propose a valuable method to address this challenge by replacing the transparent top electrode,Ag,with a 20 nm layer of *** ST-OSCs based on the 20 nm Au electrode demonstrate superior exciton extraction,more efficient charge collection,and higher color-rendering index(CRI)due to their smoother surface,higher conductivity,and enhanced visible light transmittance,resulting in a significantly higher PCE of 13.67%and an enhanced AVT of 30.17%,contributing to a high LUE of 4.15%.Additionally,optically transparent dielectric layers,applied on the front and back sides of the ST-OSCs to further boost performance,delivered an impressive LUE of 4.93%,with PCE and AVT values reaching 14.44%and 34.12%,***,the champion ST-OSCs also exhibited a favorable CRI value of *** achievements represent the bestperforming ST-OSCs to date with both high LUE and CRI and hold significant implications for the prospective commercialization of ST-OSCs.

关键词： semitransparent organic solar cells power conversion efficiency average visible transmittance light utilization efficiency color-rendering index

Subnormal Serum Liver Enzyme Levels:A Review of Pathophysiology and Clinical Significance

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journal of Clinical and Translational Hepatology 2024年第4期12卷 428-435页

作者： Elham m.Youssef George Y.wu Biochemistry Department National Research CenterCairoEgypt Department of medicine Division of Gastroenterology-HepatologyUniversity of Connecticut Health CenterFarmingtonCTUSA

Subnormal levels of liver enzymes,below the lower limit of normal on local laboratory reports,can be useful *** instance,subnormal levels of aminotransferases can be observed in vitamin B6 deficiency and chronic kidney *** alkaline phosphatase levels may indicate the presence of hypophosphatasia,Wilson's disease,deficiencies of divalent ions,or *** levels of gamma glutamyl transferase may be seen in cases of acute intrahepatic cholestasis,the use of certain medications,and in bone ***,subnormal levels of 5'-nucleotidase have been reported in lead poisoning and nonspherocytic hemolytic *** aim of this review is to bring attention to the fact that subnormal levels of these enzymes should not be ignored as they may indicate pathological conditions and provide a means of early diagnosis.

关键词： Transaminases Vitamin B6 Celiac disease Renal insufficiency Hepatolenticular Degeneration Crohn disease malnutrition Clofibrate Bone diseases Lead poisoning Anemia Hemolytic

Theoretical study of superradiant masing with solid-state spins at room temperature

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Science China(Physics,mechanics & Astronomy) 2024年第6期67卷 38-47页

作者： Qilong wu Yuan Zhang Hao wu Shi-Lei Su Kai-Kai Liu mark Oxborrow Chong-Xin Shan Klaus mølmer Henan Key Laboratory of Diamond Optoelectronic materials and Devices Key Laboratory of Material Physics Ministry of EducationSchool of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450052China Institute of Quantum materials and Physics Henan Academy of SciencesZhengzhou 450046China Center for Quantum Technology Research and Key Laboratory of Advanced Optoelectronic Quantum Architecture and measurements School of PhysicsBeijing Institute of TechnologyBeijing 100081China Beijing Academy of Quantum Information Sciences Beijing 100193China Department of materials Imperial College LondonLondon SW72AZUK Niels Bohr Institute University of CopenhagenCopenhagen 2100Denmark

Steady-state superradiance and superradiant lasing attract significant attentions in the field of optical lattice clocks,but have not been achieved yet due to the technical challenges and atom loss *** this article,we propose that their counter-part may be observed in the microwave domain with solid-state spins,i.e.,nitrogen-vacancy center spins and pentacene molecular spins,coupled to microwave resonator at room temperature with realistic technical *** validate our proposal,we investigate systematically the system dynamics and steady-state by solving quantum master equations for the multi-level and multi-process dynamics of trillions of *** calculations show that the superradiant Rabi oscillations occur firstly due to transitions among different Dicke states,and the subsequent continuous-wave superradiant masing can achieve a linewidth well below *** work may guide further exploration of transient and steady-state superradiant masing with the mentioned and other solid-state spins *** ultra-narrow linewidth may find applications in deep-space communications,radio astronomy and high-precision metrology.

关键词： solid-state spins superradiance maser

Effect of neutral polymeric bonding agent on tensile mechanical properties and damage evolution of NEPE propellant

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Defence Technology（防务技术） 2024年第2期32卷 357-367页

作者： m.wubuliaisan Yanqing wu Xiao Hou Kun Yang Hongzheng Duan Xinmei Yin State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081PR China The Fourth Institute of China Aerospace Science and Technology Corporation Xi'an710025PR China School of Aerospace Engineering Beijing Institute of TechnologyBeijing100081PR China Science and Technology on Aerospace Chemical Power Laboratory Hubei Institute of Aerospace ChemotechnologyHubei441003PR China

Introducing Neutral Polymeric bonding agents(NPBA) into the Nitrate Ester Plasticized Polyether(NEPE)propellant could improve the adhesion between filler/matrix interface, thereby contributing to the development of new generations of the NEPE propellant with better mechanical properties. Therefore,understanding the effects of NPBA on the deformation and damage evolution of the NEPE propellant is fundamental to material design and applications. This paper studies the uniaxial tensile and stress relaxation responses of the NEPE propellant with different amounts of NPBA. The damage evolution in terms of interface debonding is further investigated using a cohesive-zone model(CZm). Experimental results show that the initial modulus and strength of the NEPE propellant increase with the increasing amount of NPBA while the elongation decreases. meanwhile, the relaxation rate slows down and a higher long-term equilibrium modulus is reached. Experimental and numerical analyses indicate that interface debonding and crack propagation along filler-matrix interface are the dominant damage mechanism for the samples with a low amount of NPBA, while damage localization and crack advancement through the matrix are predominant for the ones with a high amount of NPBA. Finally, crosslinking density tests and simulation results also show that the effect of the bonding agent is interfacial rather than due to the overall crosslinking density change of the binder.

关键词： Solid propellant Bonding agent mechanical properties Damage evolution Cohesive-zone model Interface debonding

GraphFlow+:Exploiting Conversation Flow in Conversational machine Comprehension with Graph Neural Networks

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machine Intelligence Research 2024年第2期21卷 272-282页

作者： jing Hu Lingfei wu Yu Chen Po Hu mohammed j.Zaki School of Computer Science Central China Normal UniversityWuhan 430079China Pinterest San Francisco 94016USA meta Mountain View 94039USA Rensselaer Polytechnic Institute Troy 12180USA

The conversation machine comprehension(mC)task aims to answer questions in the multi-turn conversation for a single ***,recent approaches don’t exploit information from historical conversations effectively,which results in some references and ellipsis in the current question cannot be *** addition,these methods do not consider the rich semantic relationships between words when reasoning about the passage *** this paper,we propose a novel model GraphFlow+,which constructs a context graph for each conversation turn and uses a unique recurrent graph neural network(GNN)to model the temporal dependencies between the context graphs of each ***,we exploit three different ways to construct text graphs,including the dynamic graph,static graph,and hybrid graph that combines the *** experiments on CoQA,QuAC and DoQA show that the GraphFlow+model can outperform the state-of-the-art approaches.

关键词： Conversational machine comprehension(mC) reading comprehension question answering graph neural networks(GNNs) natural language processing(NLP)