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2007全国结构动力学学术研讨会

作者： M.W.Yuan E Chen Q.C.Zhao s.l.sun Y.C.Gong Y.Q.Chen Department of Mechanics and Aerospace Engineering,Peking University,Beijing,100871,China

since the size of the practical generalized eigenvalue problem is large and large,say 2 million, and the number of the required eigen pairs is more and more,say a few hundreds,the accuracy of traditional direct methods is not in guarantee,the iterative procedures are *** key problems for iterative methods are the low efficiency and the convergence criterion of *** promote the efficiency for several iterative approaches,this paper firstly implemented three efficient iterative eigenvalue algorithms-subspace iteration method,iterative Ritz vector method and iterative lanczos method based on the cell sparse fast solver and *** eigenvalue algorithms are examined under the mode error criterion,i.e.,the ratio of out-of-balance nodal forces that is the difference of maximum elastic nodal forces and maximum inertia nodal forces,and the maximum elastic nodal point ***,iterative Ritz vector method is the most efficient one among *** the mode error convergence criterion the eigenvalue extraction processes become more stable than eigenvalue-only convergence *** with ANsYs’s subspace iteration and block lanczos approaches,the subspace iteration presented here is much more efficient,and lanczos approach has roughly the equal *** methods proposed are of industrial strength and *** size tests show that the improvement in terms of CPU time and storage request is tremendous. In this paper we also reported some advances in the key measurements of the classical subspace iteration method for eigenvalue problems arising in finite element analysis,i.e.,how to choose the shifting *** aggressive shifting technique is proposed for the subspace iteration *** mode error convergence criterion is used for the eigenvalue extraction processes and made the algorithms more stable than using eigenvalue-only convergence *** tests show that the proposed aggressive shifting technique

关键词： aggressive shifting generalized eigenvalue problem finite element analysis

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Distributed swarm control for multi-robot systems inspired by shepherding behaviors

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science China(Technological sciences) 2024年第7期67卷 2191-2202页

作者： sun GuiBin GU HaiBo lÜJinHu school of Automation science and Electrical Engineering Beihang UniversityBeijing 100191China Zhongguancun laboratory Beijing 100094China

swarming behaviors play an eminent role in both biological and engineering research, and show great potential applications in many emerging fields. Traditional swarming models still lack integrity, uniformity, and stability in swarm forming processes,resulting in fragmentation and void phenomena. Inspired by the shepherding behaviors observed in nature, we propose an integrated negotiation-control scheme for distributed swarm control of massive robots. The core idea of this scheme is that the robots at the boundary of the group herd the internal robots to form an equilibrium swarm. For this purpose, we introduce a concept of virtual group center towards which boundary robots herd internal robots. Then, a distributed negotiation mechanism is designed to allow each robot to negotiate the virtual group center only through local interactions with its neighbors. After that, we propose a shepherding-inspired swarm control law to drive a group of robots to form an integrated, uniform, and stable configuration from any initial states. Both numerical and flight simulations are presented to verify the effectiveness of our proposed swarm control scheme.

关键词： swarm control multi-robot system negotiation-control scheme shepherding behavior

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Mechanics and physics under supergravity conditions

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Acta Mechanica sinica 2024年第6期40卷 1-2页

作者： Chaofeng lü Chao sun shengqiang Cai Faculty of Mechanical Engineering and Mechanics Ningbo UniversityNingbo 315211China New Cornerstone science laboratory Center for Combustion EnergyDepartment of Energy and Power EngineeringTsinghua UniversityBeijing 100084China Department of Mechanical and Aerospace Engineering University of CaliforniaSan DiegoLa Jolla CA 92093USA

"supergravity"refers to the conditions where the effective gravity is greater than that of *** conditions are generally relevant to stellar evolution,geophysical movement,astrophysical flows,and *** also frequently occur in various engineering scenarios involving acceleration,such as the launch of space shuttles,operation of rotor engines,impacts and explosions,chemical separation processes,and overloaded testing *** is already demonstrated in physiological experiments that living organisms of animals or plants could be damaged,either temporarily or permanently,when subjected to *** create supergravity conditions for scientific research on the Earth,centrifugal equipment or rapidly rotating devices are omnipresent in various fields,such as aerospace engineering,geophysical science,chemical and biomedical engineering,nuclear engineering,rotating flows,and physical modeling tests.

关键词： geophysical Earth stellar

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Experimental clearance rate and intraguild predation of jellyfish Cyanea nozakii

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Journal of Oceanology and limnology 2024年第1期42卷 128-140页

作者： Pengpeng WANG Fang ZHANG song sun shuguo lÜ CAs Key laboratory of Marine Ecology and Environmental sciences Institute of OceanologyChinese Academy of SciencesQingdao 266071China laboratory for Marine Ecology and Environmental sciences Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China University of Chinese Academy of sciences Beijing 100049China Jiaozhou Bay Marine Ecosystem Research station Chinese Academy of SciencesQingdao 266071China Center for Ocean Mega-science Chinese Academy of SciencesQingdao 266071China Institute of Marine Ecology and Environment Hainan Academy of Environmental SciencesHaikou 570100China

Cyanea nozakii,a common jellyfish distributed in offshore China,has a complex trophic relationship with other zooplankton ***,few studies have reported the predation rates and prey selection patterns of *** medusae on different prey *** is also lacking on the intraguild predation of Aurelia coerulea(another common bloom jellyfish in offshore China)by *** address the knowledge gaps,the clearance rates of *** for different prey items,including copepods(smalllarge>1000μm),fish larvae,and gelatinous prey(hydromedusae,*** ephyrae,and chaetognaths),were *** influence of predator size on the clearance rate was also ***,we examined the intraguild predation of *** on *** *** clearance rates of *** varied widely with prey organisms,being independent of prey *** organisms,except for chaetognaths,were captured with considerably high efficiency,followed by fish larvae and copepods,indicating the preferential prey selection of gelatinous organisms by *** clearance rate increased linearly with the cross-sectional area of *** size in medusae may,to some extents,underpin their capacity to capture more prey by increasing the encounter rate and capture success through *** preyed voraciously on *** in high feeding efficiency,but the clearance rate decreased with increasing ***(as prey)*** phenomenon of intraguild predation suggests a speculative hypothesis of potential population regulation of *** by *** information regarding the feeding ecology of *** reported in this study is important for understanding plankton dynamics in marine ecosystems with extensive occurrences of this jellyfish.

关键词： scyphomedusae predation rate gelatinous organisms prey selection feeding mechanism

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Co-doped Ni_(3)s_(2) nanosheet array: A high-efficiency electrocatalyst for alkaline seawater oxidation

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Nano Research 2024年第3期17卷 1050-1055页

作者： Meng Yue Xun He shengjun sun Yuntong sun Mohamed s.Hamdy Mhamed Benaissa Alsamani A.M.salih Jun liu Xuping sun College of Chemistry Chemical Engineering and Materials ScienceShandong Normal UniversityJinan 250014China Institute of Fundamental and Frontier sciences University of Electronic Science and Technology of ChinaChengdu 610054China Department of Chemistry College of ScienceKing Khalid UniversityP.O.Box 9004Abha 61413Saudi Arabia Department of Chemical Engineering College of EngineeringUniversity of Ha’ilP.O.Box 2440Ha’il 81441Saudi Arabia Department of Otolaryngology-Head&Neck surgery West China HospitalSichuan UniversityChengdu 610041China

Developing efficient and durable oxygen evolution reaction(OER)catalysts holds great promise for green hydrogen production via seawater electrolysis,but remains a ***,we report a Co-doped Ni_(3)s_(2) nanosheet array on Ni foam(Co-Ni_(3)s_(2)/NF)as a high-efficiency OER electrocatalyst for *** alkaline conditions,Co-Ni_(3)s_(2)/NF requires an overpotential of only 368 mV to drive 100 mA·cm^(–2),superior to Ni_(3)s_(2)/NF(385 mV).Besides,it exhibits at least 50-h continuous electrolysis.

关键词： Co doping Ni_(3)s_(2)nanosheet array oxygen evolution reaction seawater electrolysis electrocatalyst

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High-efficiency Carbonation Modification Methods of Recycled Coarse Aggregates

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Journal of Wuhan University of Technology(Materials science) 2024年第2期39卷 386-398页

作者：张美香 YANG Xiaolin 丁亚红 sun Bo ZHANG Xianggang lÜXiuwen Department of Civil Engineering Henan Polytechnic UniversityJiaozuo 454150China College of Architectural Engineering Xinyu UniversityXinyu 336500China

To solve the problem of only surface carbonation and realize high-efficiency carbonation of recycled coarse aggregate,the method of carbonated recycled coarse aggregate with nano materials pre-soaking was first put *** carbonation effect of modified recycled coarse aggregate with three different carbonation methods was evaluated,and water absorption,apparent density and crush index of modified recycled coarse aggregate were *** with XRD,sEM,and MIP microscopic analysis,the high-efficiency carbonation strengthening mechanism of modified recycled coarse aggregate was *** experimental results show that,compared with the non-carbonated recycled coarse aggregate,the physical and microscopic properties of carbonated recycled coarse aggregate are *** method of carbonation with nano-siO_(2) pre-soaking can realize the high-efficiency carbonation of recycled coarse aggregate,for modified recycled coarse aggregate with the method,water absorption is reduced by 23.03%,porosity is reduced by 44.06%,and the average pore diameter is 21.82 *** high-efficiency carbonation strengthening mechanism show that the pre-socked nano-siO_(2) is bound to the hydration product Ca(OH)_(2) of the old mortar with nano-scale C-s-H,which can improve the CO_(2) absorption rate,accelerate the carbonation reaction,generate more stable CaCO_(3) and nano-scale silica gel,and bond to the dense three-dimensional network structure to realize the bidirectional enhancement of nano-materials and pressurized *** is concluded that the method of carbonation with nano-siO_(2) pre-soaking is a novel high-efficiency carbonation modification of recycled coarse aggregate.

关键词： recycled coarse aggregate pressurized carbonation high-efficiency carbonation nano-siO2 strengthening mechanism

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A landscape persistence-based methodological framework for assessing ecological stability

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Environmental science and Ecotechnology 2024年第1期17卷 31-39页

作者： Da lü Yihe lü Guangyao Gao siqi sun Yi Wang Bojie Fu state Key laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesPO Box 2871Beijing100085China University of Chinese Academy of sciences Beijing100049China

Ecological stability is a critical factor in global sustainable development,yet its significance has been *** we introduce a landscape-oriented framework to evaluate ecological stability in the Qingzang Plateau(QP).Our findings reveal a medium-high stability level in the QP,with minimal changes over recent *** driving factors vary across landscape types,with climate and anthropogenic factors emerging as crucial *** anthropogenic factors are strong but unstable due to policy changes and economic development,climatic factors exert a consistent *** on our results,we propose site-specific ecological conservation and restoration *** ecological stability assessment framework provides a practical tool to understand the link between environmental conditions and ecosystems.

关键词： Ecological stability assessment framework landscape changes Nature conservation and ecological restoration Nature-based solutions Qingzang Plateau

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Divergent responses of runoff to climate change in the upper basins of the Third Pole dominated by westerlies and monsoon

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science China Earth sciences 2024年第8期67卷 2592-2614页

作者： Qikai sun Fengge sU He sun state Key laboratory of Tibetan Plateau Earth system Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of sciences Beijing 100101China

The diverse climates,distribution of snow and glaciers,and geographic locations directly affect the runoff response to climate change in the upper basins of the Third *** present,a comprehensive analysis of runoff variations and their distinct responses to climate change in the westerlies-and monsoon-dominated upper basins is still *** study comprehensively analyzed annual runoff variations in westerlies-dominated basins(the upper basins of the Aksu(UAKs),syr Darya(UsRD),Yarkant(UYK),Hotan(UHT),Amu Darya(UAMD),and Indus(UI))and monsoon-dominated basins(the upper basins of the Yangtze(UYA),Yellow(UYE),lancang(UlC),Nujiang(UNJ),and Yarlung Zangbo(UYZ))of the Third Pole from 1961 *** multi-source meteorological data and large-scale circulation factors,this study investigated the divergent responses of runoff in the upper basins to climate change,and explored the large-scale circulation mechanisms underlying runoff variations in these upper *** results showed that:(1)The annual runoff in the majority of upper basins(except for the UYE and UYZ)exhibited an increasing trend,and the annual runoff in the UAKs,UYK,and UI showed a significant increasing trend from1961 to *** annual runoff in the upper basins of the Third Pole changed abruptly from decreasing to increasing between the 1980s and 2000s,with the exception of the UYE.(2)The runoff in the monsoon-dominated upper basins has been controlled primarily by changes in precipitation over the past 55 *** contrast,the runoff in the westerlies-dominated upper basins exhibited three distinct long-term responses to climate change:temperature-dominated(UYK and UHT),precipitation-dominated(UsRD and UAMD),and the combined influence of precipitation and temperature(UAKs and UI).since the 1960s,the sensitivity of runoff to warm season temperature changes in the most westerlies-dominated upper basins has decreased,while the response of runoff to precipitation changes has intensified.(3)The stud

关键词： Upper basins of the Third Pole Climate change Westerlies and monsoon Runoff variations large-scale circulation factors

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Deep learning-based channel estimation for wireless ultraviolet MIMO communication systems

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Optoelectronics letters 2024年第1期20卷 35-41页

作者： ZHAO Taifei sun Yuxin lü Xinzhe ZHANG shuang Faculty of Automation and Information Engineering Xi'an University of TechnologyXi'an 710048China Xian Key laboratory of Wireless Optical Communication and Network Research Xi'an 710048China

To solve the problems of pulse broadening and channel fading caused by atmospheric scattering and turbulence,multiple-input multiple-output(MIMO)technology is a valid way.A wireless ultraviolet(UV)MIMO channel estimation approach based on deep learning is provided in this *** deep learning is used to convert the channel estimation into the image *** combining convolutional neural network(CNN)and attention mechanism(AM),the learning model is designed to extract the depth features of channel state information(CsI).The simulation results show that the approach proposed in this paper can perform channel estimation effectively for UV MIMO communication and can better suppress the fading caused by scattering and turbulence in the MIMO scattering channel.

关键词： channel scattering MIMO

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New perspectives on deep carbon cycling

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science China Earth sciences 2024年第8期67卷 2411-2422页

作者： Weidong sun Center of Deep sea Research Key Laboratory of Ocean Observation and ForecastingInstitute of OceanologyChinese Academy of SciencesQingdao 266071China laoshan laboratory Qingdao 266237China University of Chinese Academy of sciences Beijing 100049China

The proto-atmosphere serves as a crucial starting point for the carbon *** based on atmospheric data from Mars and Venus suggest that Earth's proto-atmosphere contained>110 bar of CO_(2)and>2.6 bar of *** protoatmosphere had over 1000 bar of water vapor during the magma ocean stage,assuming the proto-ocean had a volume of two oceans of *** this stage both water and carbon dioxide were in a supercritical state at the magma-atmosphere *** serpentinization reactions occurred due to rock-water interaction,producing abundant ***,nitrogen is reduced to ammonia,and carbon dioxide to methane,forming carbonate *** proto-atmosphere dominated by methane,ammonia,and hydrogen formed a significant amount of amino acids through *** process is essential not only to the origin of life,but also to the early carbon-nitrogen cycle on *** the Hadean eon,a large amount of CO_(2)was sequestered as carbonate and organic ***,it mainly entered the deep mantle through mantle overturn or *** the mantle transition zone,carbonate undergoes“Redox freezing”,where carbonate is reduced to diamond through oxidation of ferrous iron in the *** the lower mantle,Fe^(2+)undergoes disproportionation reactions,forming Fe^(3+)and metallic *** these,Fe^(3+)mainly resides in bridgmanite,thereby increasing the oxygen fugacity of the lower mantle,while metallic iron falls to the Earth's *** distribution of carbon in the mantle is crucial for deep carbon *** density curves of diamond and mantle peridotite melt intersect at the bottom of the mantle transition zone(about 660 km).This density crossover leads to the accumulation of diamond during the magma ocean *** materials such as subducting slabs enter the lower mantle,compensatory upwelling of lower mantle material *** enters the upper mantle,decomposes,releasing Fe^(3+)ions and oxidizes diamond

关键词： Carbon cycling Proto-atmosphere Amino acids subduction initiation Passive margin subduction Atmospheric carbon dioxide

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