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Targets capture by distributed active swarms via bio-inspired reinforcement learning

Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 210-221页

作者： Kun Xu Yue Li jun sun Shuyuan Du Xinpeng Di Yuguang Yang Bo Li Institute of Biomechanics and Medical Engineering Applied Mechanics Laboratory Department of Engineering MechanicsTsinghua University Institute of Nuclear and New Energy Technology Tsinghua University Shanghai Aerospace Control Technology Institute Shanghai Key Laboratory of Aerospace Intelligent Control Technology College of Automation Engineering Nanjing University of Aeronautics and Astronautics

Natural swarms arranged from cells to herds are usually decentralized but display intriguing collective intelligence in coordinating individuals across large scales to efficiently achieve their common goals. Learning from nature may provide new strategies for controlling collective dynamics of synthetic swarms to accomplish specific functions. Here, we present a bioinspired computational framework that steers distributed active swarms to collectively capture and merge targets via reinforcement learning. We exploit collective milling structures of natural herds to cage the targets, and adopt a switching control policy inspired by sperms' chiral dynamics to optimize the trajectories of individuals, through which the active swarms can selforganize to enclose single or multiple distant targets in a dynamical, adaptive and scalable manner. There exists a critical swarm size, beyond which the excessive competition between agents would generate large mechanical forces, leading to capture instability but enabling the transition from short-distance to long-distance merging capture of multiple targets. This work provides physical insights into distributed active swarms and could offer a multilevel, decentralized strategy toward controlling swarm robotics in wide applications such as bio-medical devices, machine immunity, and target clearance.

关键词： swarm intelligence robotics multi-tasks artificial intelligence bionics

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How Many Pathways We Have for the Marine Carbon Neutrality

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Journal of Earth Science 2023年第5期34卷 1621-1623页

作者： jun sun Institute for Advanced Marine Research CUG Guangzhou 511462China State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesWuhan 430078China College of Marine Science and Technology China University of GeosciencesWuhan 430074China

Global warming is one of the major challenges that the international community is currently *** Intergovernmental Panel on Climate Change(IPCC)has indicated that if the concentration of greenhouse gases in the atmosphere continues to rise,global warming is expected to pose risks to future food security,as well as to human health and wealth in the 21st *** became the world’s largest emitter of greenhouse gases in *** 2018,the global emission of greenhouse gases was 33.1 billion metric tons of CO_(2),with China accounting for 28%of the total global emission,ranking first *** to estimates by the Chinese Academy of Engineering,China will reach its peak carbon dioxide emissions in 2027 at 12.2 billion metric tons of CO_(2),making it imperative to achieve carbon neutrality and achieve harmony between humans and nature as soon as possible.

关键词： gases Marine harmony

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Daily extreme precipitation and trends over China

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Science China Earth Sciences 2017年第12期60卷 2190-2203页

作者： sun jun ZHANG FuQing National Meteorological Center China Meteorological Administration Department of Meteorology and Atmospheric Sciences and Center for Advanced Data Assimilation and Predictability TechniquesPennsylvania State UniversityUniversity Park

Based on daily precipitation data of more than 2000 Chinese stations and more than 50 yr, we constructed time series of extreme precipitation based on six different indices for each station: annual and summer maximum(top-1) precipitation,accumulated amount of 10 precipitation maxima(annual, summer; top-10), and total annual and summer ***, we constructed the time series of the total number of stations based on the total number of stations with top-1 and top-10 annual extreme precipitation for the whole data period, the whole country, and six subregions, respectively. Analysis of these time series indicate three regions with distinct trends of extreme precipitation:(1) a positive trend region in Southeast China,(2) a positive trend region in Northwest China, and(3) a negative trend region in North China. Increasing(decreasing)ratios of 10–30% or even >30% were observed in these three regions. The national total number of stations with top-1 and top-10 precipitation extremes increased respectively by 2.4 and 15 stations per decade on average but with great inter-annual *** have been three periods with highly frequent precipitation extremes since 1960:(1) early 1960 s,(2) middle and late 1990 s,and(3) early 21 st century. There are significant regional differences in trends of regional total number of stations with top-1 and top-10 precipitation. The most significant increase was observed over Northwest China. During the same period, there are significant changes in the atmospheric variables that favor the decrease of extreme precipitation over North China: an increase in the geopotential height over North China and its upstream regions, a decrease in the low-level meridional wind from South China coast to North China, and the corresponding low moisture content in North China. The extreme precipitation values with a50-year empirical return period are 400–600 mm at the South China coastal regions and gradually decrease to less than 50

关键词： Extreme precipitation(EP) Extreme precipitation event(EPE) Time series Total annual number of stations Extreme event return level

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Mechanical properties of molybdenum products prepared by using molybdenum powders with different micro-morphologies

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Rare Metals 2015年第4期34卷 276-281页

作者： Geng An jun sun Ren-Zhi Liu Jing Li Yuan-jun sun State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong University Technical Center Jinduicheng Molybdenum Co. Ltd

Using two kinds of molybdenum （Mo） powders with different micro-morphologies as raw materials, the Mo wires with a diameter of 0.18 mm and Mo sheets with thickness of 0.5 and 0.2 mm were prepared at the same process of pressing, sintering, drawing, or rolling, respectively. By comparative analysis on the microstructure and mechanical properties of Mo wires and Mo sheets, the effect of Mo powder micro-morphology on properties and quality of Mo products was studied. The results show that, compared with that prepared by traditional Mo powder with inhomogeneous particle size and aggregation, the Mo wires prepared by specific Mo powder with homogeneous particle sizes, less agglomeration, and better dispersion exhibit higher yield, higher tensile strength, and lower elongation at room temperature, and the Mo sheets also show excellent high-temperature performances and better isotropy. The essential reason for those is the difference of Mo powder micro-morphology. Inhomogeneous particle size and aggregation of Mo powder greatly influence the microstructure of Mo sintered compacts and mechanical properties of Mo products.

关键词： Molybdenum powder Micro-morphology Aggregation Molybdenum product Mechanical property

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In situ investigation of the mechanical properties of nanomaterials by transmission electron microscopy

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Acta Mechanica Sinica 2012年第6期28卷 1513-1527页

作者： jun sun Feng Xu Li-Tao sun SEU-FEI Nano-Pico Center Key Laboratory of MEMS of Ministry of Education Southeast University

With the progress of modern transmission elec- tron microscopy （TEM） and development of dedicated func- tional TEM specimen holders, people can now manipulate a nano-object with nanometer-range precision and simulta- neously acquire mechanical data together with atomic-scale structural information. This advanced methodology is play- ing an increasingly important role in nanomechanics. The present review summarizes relevant studies on the in situ in- vestigation of mechanical properties of various nanomateri- als over the past decades. These works enrich our knowledge not only on nanomaterials （such as carbon nanotubes, car- bon onions, boron nitride nanotubes, silicon nanowires and graphene, etc.） but also on mechanics at the nanoscate.

关键词： Nanomaterials Transmission electron mi-croscopy In situ Nanoscale mechanics

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Gradient Estimate for the Positive Solutions of Lu=0 and Lu=?u/?t on Conformal Solitons

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Acta Mathematica Sinica,English Series 2021年第11期37卷 1768-1782页

作者： Xiang LI jun sun School of Mathematical Sciences University of Science and Technology of ChinaHefei 230026P.R.China School of Mathematics and Statistics Wuhan UniversityWuhan 430072P.R.China Hubei Key Laboratory of Computational Science Wuhan UniversityWuhan 430072P.R.China

In this paper,we prove gradient estimates for the positive solutions of Lu=0 and Lu=?u/?t on conformal solitons,where L(·)=Δ(·)+.We also give some applications for them.

关键词： Gradient estimate conformal solitons

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Pretreating and normalizing metabolomics data for statistical analysis

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Genes & Diseases 2024年第3期11卷 188-205页

作者： jun sun Yinglin Xia Division of Gastroenterology and Hepatology Department of MedicineDepartment of Microbiology/ImmunologyUIC Cancer CenterUniversity of Illinois ChicagoJesse Brown VA Medical Center Chicago(537)ChicagoIL 60612USA Division of Gastroenterology and Hepatology Department of MedicineUniversity of Illinois ChicagoChicagoIL 60612USA

Metabolomics as a research field and a set of techniques is to study the entire small molecules in biological *** is emerging as a powerful tool generally for pre-cision ***,integration of microbiome and metabolome has revealed the mechanism and functionality of microbiome in human health and ***,metabo-lomics data are very ***/pretreating and normalizing procedures on metabolomics data are usually required before statistical *** this review article,we comprehensively review various methods that are used to preprocess and pretreat metabolo-mics data,including MS-based data and NMR-based data preprocessing,dealing with zero and/or missing values and detecting outliers,data normalization,data centering and scaling,data *** discuss the advantages and limitations of each *** choice for a suitable preprocessing method is determined by the biological hypothesis,the characteristics of the data set,and the selected statistical data analysis *** then provide the perspective of their applications in the microbiome and metabolome research.

关键词： Data centering and scaling Data normalization Data transformation Missing values MS-Baseddata preprocessing NMRData preprocessing Outliers Preprocessing/pretreatment

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Concentrations and sinking rates of transparent exopolymer particles(TEPs)in a coastal sea:the Changjiang River(Yangtze River)Estuary

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Acta Oceanologica Sinica 2020年第10期39卷 58-69页

作者： Shujin Guo jun sun College of Marine Science and Technology China University of Geosciences(Wuhan)Wuhan 430074China Jiaozhou Bay Marine Ecosystem Research Station Institute of OceanologyChinese Academy of SciencesQingdao 266071China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China

Transparent exopolymer particles(TEPs)are ubiquitous throughout the oceans,and their sedimentation is considered an efficient biological carbon sink *** investigate the role of coastal TEPs in sinking carbon from the upper layer,samples were collected in the spring and summer of 2011 in the Changjiang River(Yangtze River)Estuary,a typical coastal *** concentrations and sinking rates of TEPs were measured,and potential sedimentation flux of TEPs was *** concentrations ranged from 40.00μg/L to 1040.00μg/L(mean=(209.70±240.93)μg/L)in spring and 56.67μg/L to 1423.33μg/L(mean=(433.33±393.02)μg/L)in summer,and they were higher at bloom stations than at non-bloom stations during both cruises.A significant positive correlation between TEPs concentration and chlorophyll a(Chl a)concentration was detected,suggesting that phytoplankton was the primary source of TEPs in this *** sinking rates ranged from 0.08 m/d to 0.57 m/d with a mean of(0.28±0.14)m/d in spring and 0.10 m/d to 1.08 m/d with a mean of(0.34±0.31)m/d in *** potential sedimentation flux of TEP-C ranged from 4.95 mg/(m2·d)to 29.40 mg/(m2·d)with a mean of(14.66±8.83)mg/(m2·d)in spring and 6.80 mg/(m2·d)to 30.45 mg/(m2·d)with a mean of(15.71±8.73)mg/(m2·d)in summer,which was^17.81%to 138.27%(mean=65.15%±31.75%)of sedimentation flux of phytoplankton cells in the study *** to the increase of TEPs concentrations and their sinking rates,sedimentation fluxes of TEPs at the bloom station were obviously higher than at the non-bloom station during both *** study indicates that TEPs serve as a carbon sink in the Changjiang River Estuary,especially during bloom events,and their sedimentation should be taken into account when we study the carbon sedimentation in the coastal sea.

关键词： transparent exopolymer particles sinking rates Changjiang River(Yangtze River)Estuary coastal sea

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Graph-matching-based character recognition for Chinese seal images

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Science China(Information Sciences) 2019年第9期62卷 37-50页

作者： Bin sun Shaojun HUA Shutao LI jun sun College of Electrical and Information Engineering Hunan University Information Department Fujitsu Research and Develop Center

Recognizing characters in Chinese seal images is important when researching ancient cultural artworks because the seals may contain critical historical information. However, owing to large intraclass variance and a limited number of training samples, recognizing such characters in Chinese seals is ***, this study proposes a graph-matching-based method to recognize characters in historical Chinese seal images. In the proposed method, a Chinese seal character is first modeled as a graph representing its underlying geometric structure. Then, two affinity matrices that measure the similarity of nodes and edge pairs are calculated with their local features. Finally, a correspondence matrix is calculated using a graph matching algorithm and the most similar reference is selected as the recognition result. Compared with several existing classification methods for seal image recognition, the proposed graph-matching-based method achieves better results, particularly in the case of limited samples.

关键词： graph model Chinese seal character recognition graph matching

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Inertial parameter estimation and control of non-cooperative target with unilateral contact constraint

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Chinese Journal of Aeronautics 2021年第3期34卷 225-240页

作者： Shuang LI Yuchen SHE jun sun College of Astronautics Nanjing University of Aeronautics and AstronauticsNanjing 210016China Shanghai Aerospace Control Technology Institute Shanghai 201109China Shanghai Key Laboratory of Aerospace Intelligent Control Technology Shanghai 201109China

In this paper, the relative sliding motion between the target and the manipulator’s endeffector is considered and characterized as a unilateral contact constraint. A new possible solution is presented to estimate the inertial parameters of a non-cooperative target while the relative sliding motion exists. First, the detailed analysis of the dynamical model is presented, and a parameterexplicit linear time-varying model is obtained. Then, an extended state observer is constructed based on the new model, which can effectively estimate the unknown inertial parameters of the target when relative sliding motion exists. As the modified reactionless controller requires the knowledge of inertial parameters, a hybrid post-capture control scheme is also established based on the switch law between different controllers. The correctness and efficiency of the proposed algorithm are validated by numerical simulation, which proves a potential framework for the non-cooperative target postcapture operation.

关键词： Non-cooperative object On-orbit servicing Post-capture control Parameter estimation Unilateral contact constraint

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