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Earth and Planetary Physics 2024年第1期8卷 204-214页

作者： A.M.Jorgensen TianRan sun y.Huang l.li R.Xu l.Dai Chi Wang New Mexico Institute of Mining and Technology SocorroNMUSA National Space Science Center Chinese Academy of SciencesBeijing 100190China Tsinghua University Beijing 100084China

Following our earlier work on tomographic reconstruction of the magnetosheath soft X-ray emissions with superposed epoch analysis of many images recorded from a single spacecraft we now explore the instantaneous reconstruction of the magnetosheath and magnetopause using a few images recorded simultaneously from a few *** work is motivated by the prospect of possibly having two or three soft X-ray imagers in space in the coming years,and that many phenomena which occur at the magnetopause boundary,such as reconnection events and pressure pulse responses,do not lend themselves as well to superposed epoch *** the reconstruction is successful-which we demonstrate in this paper that it can be-this collection of imagers can be used to reconstruct the magnetosheath and magnetopause from a single image from each spacecraft,allowing for high time resolution *** this paper we explore the reconstruction using,two,three,and four *** show that the location of the subsolar point of the magnetopause can be determined with just two satellites,and that volume emissions of soft X-rays,and the shape of the boundary,can be reconstructed using three or more satellites.

关键词： magnetosheath tomography soft X-ray imaging SMIlE

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

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

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

MAVEN observation of magnetosonic waves in the Martian magnetotail region

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Earth and Planetary Physics 2024年第2期8卷 317-325页

作者： ShangChun Teng JiCheng sun JiaWei Gao y.Harada Markus Fraenz DeSheng Han State Key laboratory of Marine Geology School of Ocean and Earth ScienceTongji UniversityShanghai 200092China MNR Key laboratory for Polar Science Polar Research Institute of ChinaShanghai 200136China Key laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Department of Geophysics Kyoto UniversityKyotoJapan Max-Planck-Institute for Solar System Research GoettingenGermany

Magnetosonic waves are an important medium for energy transfer in collisionless space *** waves have been widely investigated in the upstream of the bow shock at *** waves are believed to originate from pickup ions or reflected *** utilizing MAVEN spacecraft data,we have observed the occurrence of quasi-perpendicularly propagating magnetosonic emissions near the proton gyrofrequency in the Martian magnetotail *** plasma waves are associated with a significant enhancement of proton and oxygen *** excited magnetosonic waves could possibly heat the protons through resonance and facilitate the ionospheric plasma *** results could be helpful to better understand the Mars’magnetospheric dynamics and offer insights into possible energy redistribution between waves and plasma in the Martian nightside magnetosphere.

关键词： Martian magnetotail region magnetosonic waves proton escape

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On B(5,20)2-Groups

Algebra Colloquium 2024年第3期31卷 429-440页

作者： E.A.Alhassan y.l.Tan y.li School of Mathematical Sciences Jiangsu UniversityZhenjiangJiangsu 212013China Department of Mathematics Brock UniversitySt.CatharinesOntario L2S 3A1Canada

A finite group G is said to be a B(n,k)group if for any n-element subset[a_(1),…,a_(n)]of G,|{a_(i)a_(j)|1≤i,j≤n}|≤*** is of interest to characterize the structure of B(n,k)groups for n(n+1)/2≤k≤n^(2)-*** B(5,k)groups for 15≤k≤19 have been investigated by several *** this paper,we give a complete characterization of B(5,20)2-groups by showing there are five classes of such groups which are nontrivial and nonabelian.

关键词： B(n,k)groups small squaring property central extension GAP

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

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

Deep bed filtration model for cake filtration and erosion

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Applied Mathematics and Mechanics(English Edition) 2024年第2期45卷 355-372页

作者： l.I.KUZMINA y.V.OSIPOV A.R.PESTEREV Department of Applied Mathematics HSE UniversityMoscow 101000Russia Department of Computer Science and Applied Mathematics Moscow State University of Civil EngineeringMoscow 129337Russia

Many phenomena in nature and technology are associated with the filtration of suspensions and colloids in porous media. Two main types of particle deposition,namely, cake filtration at the inlet and deep bed filtration throughout the entire porous medium, are studied by different models. A unified approach for the transport and deposition of particles based on the deep bed filtration model is proposed. A variable suspension flow rate, proportional to the number of free pores at the inlet of the porous medium, is considered. To model cake filtration, this flow rate is introduced into the mass balance equation of deep bed filtration. For the cake filtration without deposit erosion,the suspension flow rate decreases to zero, and the suspension does not penetrate deep into the porous medium. In the case of the cake filtration with erosion, the suspension flow rate is nonzero, and the deposit is distributed throughout the entire porous medium. An exact solution is obtained for a constant filtration function. The method of characteristics is used to construct the asymptotics of the concentration front of suspended and retained particles for a filtration function in a general form. Explicit formulae are obtained for a linear filtration function. The properties of these solutions are studied in detail.

关键词： deep bed filtration cake filtration porous medium particle deposition and erosion analytical solution concentration front