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Coupled two-dimensional discrete element and multibody dynamic modeling for interaction of the soil and rough shaped rigid bodies

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Acta Mechanica Sinica 2022年第7期38卷 148-163,I0004页

作者： Ning Ding Jinyang Liu Caishan Liu Department of Engineering Mechanics School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China State Key Laboratory of Turbulence and Complex System College of EngineeringPeking UniversityBeijing100871China

The study of soil and rigid body system interactions is very important for the exploration of the Moon and Mars *** discrete element method(DEM)is a relatively accurate simulation method to study dry sand soil mechanical ***,it is not suitable for bodies that are in mutual contact,connected due to constraints or have complex inertia properties due to their *** efficient combination of the two-dimensional discrete element and multibody dynamic modeling method is proposed to solve the problem,in which the contacts and frictions among the granular spheres and the multibody system,including the smooth and rough rigid bodies,are taken into *** this work,the soil field is modeled by a two-dimensional DEM,and the dynamics of the constrained rigid body system are modeled by the Cartesian method.A detection algorithm is developed to address the interactions between spherical discrete elements and roughly shaped rigid *** advantage of this coupled method is that it enables the simultaneous capture of both ***,the program is verified by simulation experiments of the three-ball collision and the collision among the rectangular bars and the three *** on this,the movement of the toothed wheel in the granular matter is analyzed,and the results show that the wheel with six teeth and 30°inclination has the fastest forward *** extraterrestrial objects,the wheel grip worsens,but the forward speed first increases and then decreases with decreasing gravity acceleration and loads on wheels,which proves that the coupled two-dimensional DEM and multibody dynamic program is effective in solving engineering problems.

关键词： Discrete element method Multibody dynamic system Rough-shaped rigid body Toothed wheel in granular matter

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Paddy Rice Mapping Based on Phenology Matching and Cultivation Pattern Analysis Combining Multi-Source Data in Guangdong, China

Journal of Remote Sensing (United States)

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Journal of Remote Sensing (United states) 2024年 4卷

作者： Sun, Lingyu Yang, Tianyao Lou, Yuxin Shi, Qian Zhang, Liangpei State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing Wuhan University Wuhan China Sino-French Institute for Earth System Science College of Urban and Environmental Sciences Peking University Beijing China College of Global Change and Earth System Science Beijing Normal University Beijing China Guangdong Provincial Key Laboratory for Urbanization and Geo-simulation School of Geography and Planning Sun Yat-sen University Guangzhou China

Paddy rice mapping is crucial for cultivation management, yield estimation, and food security. Guangdong, straddling tropics and subtropics, is a major rice-producing region in China. Mapping paddy rice in Guangdong is essential. However, there are 2 main difficulties in tropical and subtropical paddy rice mapping, including the lack of high-quality optical images and differences in paddy rice planting times. This study proposed a paddy rice mapping framework using phenology matching, integrating Sentinel-1 and Sentinel-2 data to incorporate prior knowledge into the classifiers. The transplanting periods of paddy rice were identified with Sentinel-1 data, and the subsequent 3 months were defined as the growth periods. Features during growth periods obtained by Sentinel-1 and Sentinel-2 were inputted into machine learning classifiers. The classifiers using matched features substantially improved mapping accuracy compared with those using unmatched features, both for early and late rice mapping. The proposed method also improved the accuracy by 6.44% to 16.10% compared with 3 other comparison methods. The model, utilizing matched features, was applied to early and late rice mapping in Guangdong in 2020. Regression results between mapping area and statistical data validate paddy rice mapping credibility. Our analysis revealed that thermal conditions, especially cold severity during growing stages, are the primary determinant of paddy rice phenology. Spatial patterns of paddy rice in Guangdong result from a blend of human and physical factors, with slope and minimum temperature emerging as the most important limitations. These findings enhance our understanding of rice ecosystems' dynamics, offering insights for formulating relevant agricultural policies. © 2024 Lingyu Sun et al.

关键词： Cultivation

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Time-sequential color code division multiplexing holographic display with metasurface

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Opto-Electronic Advances 2023年第8期6卷 8-16页

作者： Xin Li Qinmiao Chen Xue Zhang Ruizhe Zhao Shumin Xiao Yongtian Wang Lingling Huang Beijing Engineering Research Center of Mixed Reality and Advanced Display School of Optics and PhotonicsBeijing Institute of TechnologyBeijing 100081China MoE Key Laboratory of Photoelectronic Imaging Technology and System and MIIT Key Laboratory of Photonics Information TechnologySchool of Optics and PhotonicsBeijing Institute of TechnologyBeijing 100081China State Key Laboratory on Tunable Laser Technology Ministry of Industry and Information Technology Key Lab of Micro-Nano Optoelectronic Information SystemHarbin Institute of Technology(Shenzhen)Shenzhen 518055China National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Harbin Institute of TechnologyHarbin 150080China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China

Color metasurface holograms are powerful and versatile platforms for modulating the amplitude,phase,polarization,and other properties of light at multiple operating ***,the current color metasurface holography can only realize static *** this study,we propose and demonstrate a multiplexing metasurface technique combined with multiwavelength code-division multiplexing(CDM)to realize dynamic *** code references are utilized to record information within a single metasurface and increase the information capacity and security for anticracks.A total of 48 monochrome images consisting of pure color characters and multilevel color video frames were reconstructed in dual polarization channels of the birefringent metasurface to exhibit high information density,and a video was displayed via sequential illumination of the corresponding code patterns to verify the ability of dynamic *** approach demonstrates significant application potential in optical data storage,optical encryption,multiwavelengthversatile diffractive optical elements,and stimulated emission depletion microscopy.

关键词： metasurface color holography dynamic display code division multiplexing

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Classification framework and semantic labeling for Big Earth Data

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Big Earth Data 2023年第3期7卷 886-903页

作者： Juanle Wang Kun Bu Dongmei Yan Jingyue Wang Bowen Duan Min Zhang Guojin He State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciencesand Natural Resources ResearchChinese Academy of SciencesBeijingChina Collaborative InnovationCenter for Development and Utilization of Geographic Information Resources in Jiangsu Province NanjingChina Northeast Institute of Geography and Agroecology Chinese Academy of SciencesChangchunChina International Research Center of Big Data for Sustainable Development Goals BeijingChina Schoolof Civil and Architectural Engineering Shandong University of TechnologyZiboChina College of Resourceand Environment University of Chinese Academy of SciencesBeijingChina

Big Earth Data refers to the multidimensional integration and association of scientific data,including geography,resources,environment,ecology,and *** effective data classification system and label management strategy are important foundations for long-term management of data *** objective of this study was to construct a classification system and realize multidimensional semantic data label management for the Big Earth Data Science engineering Program(CASEarth).This study constructed two sets of classification and coding systems that realize classification by mapping each other;namely,the geosphere-level and Sustainable Development Goals(SDGs)indicator *** technique was based on natural language processing technology and solved problems with subject-word segmentation,weight calculation,and dynamic matching.A prototype system for classification and label management was constructed based on existing CASEarth datasets of more than 1,***,we expect our study to provide the methodology and technical support for useroriented classification and label management services for Big Earth Data.

关键词： Big Earth Data CASEarth scientific engineering data classification data labeling data management

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A unified framework of temporal information expression in geosciences knowledge system

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Geoscience Frontiers 2023年第5期14卷 343-352页

作者： Shu Wang Yunqiang Zhu Yanmin Qi Zhiwei Hou Kai Sun Weirong Li Lei Hu Jie Yang Hairong Lv State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Nanjing 210023China University of Nottingham Ningbo China Faculty of Science and EngineeringNingbo 315154China Guangzhou Institute of Geography Guangdong Academy of SciencesGuangzhou 510070China University of Chinese Academy of Sciences Beijing 100101China Department of Automation Tsinghua UniversityBeijing 100084China

Time is an essential reference system for recording objects,events,and processes in the field of *** are currently various time references,such as solar calendar,geological time,and regional calendar,to represent the knowledge in different domains and regions,which subsequently entails a time conversion process required to interpret temporal information under different time ***,the current time conversion method is limited by the application scope of existing time ontologies(e.g.,“Jurassic”is a period in geological ontology,but a point value in calendar ontology)and the reliance on experience in conversion *** issues restrict accurate and efficient calculation of temporal information across different time *** address these issues,this paper proposes a Unified Time Framework(UTF)in the geosciences knowledge *** to a systematic time element parsing from massive time references,the proposed UTF designs an independent time root node to get rid of irrelevant nodes when accessing different time types and to adapt to the time expression of different geoscience ***,this UTF carries out several designs:to ensure the accuracy of time expressions by designing quantitative relationship definitions;to enable time calculations across different time elements by designing unified time nodes and structures,and to link to the required external ontologies by designing adequate *** comparing the time conversion methods,the experiment proves the UTF greatly supports accurate and efficient calculation of temporal information across different time references in SPARQL ***,it shows a higher and more stable performance of temporal information queries than the time conversion *** the advent of the Big Data era in the geosciences,the UTF can be used more widely to discover new geosciences knowledge across different time references.

关键词： Unified Time Framework(UTF) Time ontology Geosciences knowledge system Time conversion Time scale Big data

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Traj-LLM: A New Exploration for Empowering Trajectory Prediction With Pre-Trained Large Language Models

IEEE Transactions on Intelligent Vehicles

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IEEE Transactions on Intelligent Vehicles 2024年 1-14页

作者： Lan, Zhengxing Liu, Lingshan Fan, Bo Lv, Yisheng Ren, Yilong Cui, Zhiyong School of Transportation Science and Engineering Beihang University Beijing China Beijing Key Laboratory of Traffic Engineering College of Metropolitan Transportation Beijing University of Technology Beijing China State Key Laboratory of Multimodal Artificial Intelligence Systems Institute of Automation Chinese Academy of Sciences Beijing China School of Transportation Science and Engineering State Key Lab of Intelligent Transportation System Beihang University Beijing China

Predicting the future trajectories of dynamic traffic actors is a cornerstone task in autonomous driving. Though existing notable efforts have resulted in impressive performance improvements, a gap persists in scene cognitive and understanding of complex traffic semantics. This paper proposes Traj-LLM, the first to investigate the potential of using pre-trained Large Language Models (LLMs) without explicit prompt engineering to generate future motions from vehicular past trajectories and traffic scene semantics. Traj-LLM starts with sparse context joint encoding to dissect the agent and scene features into a form that LLMs understand. On this basis, we creatively explore LLMs' strong understanding capability to capture a spectrum of high-level scene knowledge and interactive information. To emulate the human-like lane focus cognitive function and enhance Traj-LLM's scene comprehension, we introduce lane-aware probabilistic learning powered by the Mamba module. Finally, a multi-modal Laplace decoder is designed to achieve scene-compliant predictions. Extensive experiments manifest that Traj-LLM, fueled by prior knowledge and understanding prowess of LLMs, together with lane-aware probability learning, transcends the state-of-the-art methods across most evaluation metrics. Moreover, the few-shot analysis serves to substantiate Traj-LLM's performance, as even with merely 50% of the dataset, it surpasses the majority of benchmarks relying on complete data utilization. This study explores endowing the trajectory prediction task with advanced capabilities inherent in LLMs, furnishing a more universal and adaptable solution for forecasting agent movements in a new way. IEEE

关键词： Semantics

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Design and Experimental Validation of Sealing Assembly for Lunar Regolith Volatile Extraction Heating Furnace

Design and Experimental Validation of Sealing Assembly for L...

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2023 IEEE International Conference on Robotics and Biomimetics, ROBIO 2023

作者： Zhang, Hongan Tang, Junyue Wang, Yinchao Lu, Zixiao Wang, Bo Cao, Miaoyan Jiang, Shengyuan Yanshan University Mechanical Engineering Qinhuangdao China Harbin Institute of Technology State Key Laboratory of Robotics and System Harbin China Shenyang Aerospace University Mechatronics Institute Shenyang China Chinese Academy of Science National Center for Nanoscience and Technlogy Beijing China China Academy of Space Technology Beijing China

ISBN: (纸本)9798350325706

A lunar regolith in-situ analysis payload deploying a mass spectrometer is proposed to exactly detect the water ice of the South Pole of the moon for China future lunar exploration missions. In order to realize the goal, an airtight heating furnace for volatile extraction from lunar regolith is desired. In this paper, sealing methods for lunar regolith volatile in heating furnace to future proposed in-situ sampling and analysis of lunar samples were investigated based on power requirements, furnace closing accuracy requirements, dust tolerance and operation in the Lunar environment. Methods implemented include a balanced metal hollow ring seal, a double channel ferrule tab ring radial seal and a spring energized seal. Comparing the performance of sealing methods under the above conditions, a spring energized seal is selected as the heating furnace seal. The materials and structure of the seal are designed based on the rigidity requirements, leakage rate requirements and working environment requirements. In order to test the sealing performance of seals after repeated sealing in high and low temperature environments, a seal leak detection system was designed. The test results indicate that the seal can meet the sealing performance requirements after repeated sealing at various temperatures. © 2023 IEEE.

关键词： Dust tolerance Leakage rate Lunar environment Repeated sealing Spring energized seal

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The missing base molecules in atmospheric acid-base nucleation

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National Science Review 2022年第10期9卷 196-208页

作者： Runlong Cai Rujing Yin Chao Yan Dongsen Yang Chenjuan Deng Lubna Dada Juha Kangasluoma Jenni Kontkanen Roope Halonen Yan Ma Xiuhui Zhang Pauli Paasonen Tuukka Pet?j? Veli-Matti Kerminen Yongchun Liu Federico Bianchi Jun Zheng Lin Wang Jiming Hao James N.Smith Neil M. Donahue Markku Kulmala Douglas R.Worsnop Jingkun Jiang State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Institute for Atmospheric and Earth System Research/Physics Faculty of Science University of Helsinki Aerosol and Haze Laboratory Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical Technology Collaborative Innovation Center of Atmospheric Environment and Equipment Technology Nanjing University of Information Science and Technology Laboratory of Atmospheric Chemistry Paul Scherrer Institute Center for Joint Quantum Studies and Department of Physics School of Science Tianjin University Key Laboratory of Cluster Science Ministry of Education of China School of Chemistry and Chemical Engineering Beijing Institute of Technology Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3) Department of Environmental Science and Engineering Fudan University Chemistry Department University of California Center for Atmospheric Particle Studies Carnegie Mellon University Department of Chemistry Carnegie Mellon University Aerodyne Research Inc.

Transformation of low-volatility gaseous precursors to new particles affects aerosol number concentration,cloud formation and hence the *** clustering of acid and base molecules is a major mechanism driving fast nucleation and initial growth of new particles in the ***,the acid-base cluster composition,measured using state-of-the-art mass spectrometers,cannot explain the measured high formation rate of new *** we present strong evidence for the existence of base molecules such as amines in the smallest atmospheric sulfuric acid clusters prior to their detection by mass *** demonstrate that forming（H2SO4）1（amine）1is the rate-limiting step in atmospheric H2SO4-amine nucleation and the uptake of（H2SO4）1（amine）1is a major pathway for the initial growth of *** proposed mechanism is very consistent with measured new particle formation in urban beijing,in which dimethylamine is the key base for H2SO4nucleation while other bases such as ammonia may contribute to the growth of larger *** findings further underline the fact that strong amines,even at low concentrations and when undetected in the smallest clusters,can be crucial to particle formation in the planetary boundary layer.

关键词： new particle formation acid-base nucleation aerosol polluted urban environment

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Synergetic roadmap of carbon neutrality and clean air for China

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Environmental Science and Ecotechnology 2023年第4期16卷 1-25页

作者： Qiang Zhang Zhicong Yin Xi Lu Jicheng Gong Yu Lei Bofeng Cai Cilan Cai Qimin Chai Huopo Chen Hancheng Dai Zhanfeng Dong Guannan Geng Dabo Guan Jianlin Hu Cunrui Huang Jianing Kang Tiantian Li Wei Li Yongsheng Lin Jun Liu Xin Liu Zhu Liu Jinghui Ma Guofeng Shen Dan Tong Xuhui Wang Xuying Wang Zhili Wang Yang Xie Honglei Xu Tao Xue Bing Zhang Da Zhang Shaohui Zhang Shaojun Zhang Xian Zhang Bo Zheng Yixuan Zheng Tong Zhu Jinnan Wang Kebin He Ministry of Education Key Laboratory for Earth System Modelling Department of Earth System ScienceTsinghua UniversityBeijing100084China Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science&TechnologyNanjing210044China State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing100084China Institute for Carbon Neutrality Tsinghua UniversityBeijing100084China State Key Joint Laboratory for Environment Simulation and Pollution Control College of Environmental Sciences and Engineering and Center for Environment and HealthPeking UniversityBeijing100871China Center of Air Quality Simulation and System Analysis Chinese Academy of Environmental PlanningBeijing100012China Center for Carbon Neutrality Chinese Academy of Environmental PlanningBeijing100012China National Center for Climate Change Strategy and International CooperationBeijing100035China Nansen-Zhu International Research Centre Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China College of Environmental Sciences and Engineering Peking UniversityBeijing100871China Institute of Environmental Policy Management Chinese Academy of Environmental PlanningBeijing100012China Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control School of Environmental Science and EngineeringCollaborative Innovation Center of Atmospheric Environment and Equipment TechnologyNanjing University of Information Science and TechnologyNanjing210044China Vanke School of Public Health Tsinghua UniversityBeijing100084China Center for Energy and Environmental Policy Research Beijing Institute of TechnologyBeijing100081China China CDC Key Laboratory of Environment and Population Health National Institute of En

It is well recognized that carbon dioxide and air pollutants share similar emission sources so that synergetic policies on climate change mitigation and air pollution control can lead to remarkable co-benefits on greenhouse gas reduction,air quality improvement,and improved *** the context of carbon peak,carbon neutrality,and clean air policies,this perspective tracks and analyzes the process of the synergetic governance of air pollution and climate change in China by developing and monitoring 18 *** 18 indicators cover the following five aspects:air pollution and associated weather-climate conditions,progress in structural transition,sources,inks,and mitigation pathway of atmospheric composition,health impacts and benefits of coordinated control,and synergetic governance system and *** tracking the progress in each indicator,this perspective presents the major accomplishment of coordinated control,identifies the emerging challenges toward the synergetic governance,and provides policy recommendations for designing a synergetic roadmap of Carbon Neutrality and Clean Air for China.

关键词： Carbon neutrality Clean air Synergetic roadmap

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The role of botanical triterpenoids and steroids in bile acid metabolism,transport,and signaling:Pharmacological and toxicological implications

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Acta Pharmaceutica Sinica B 2024年第8期14卷 3385-3415页

作者： Zichen Luo Wei Zhou Tong Xie Weichen Xu Chen Shi Zihan Xiao Yu Si Yan Ma Qingling Ren Liuqing Di Jinjun Shan Medical Metabolomics Center Institute of PediatricsJiangsu Key Laboratory of Children’s Health and Chinese MedicineNanjing University of Chinese MedicineNanjing 210023China State Key Laboratory of Natural Medicines School of Traditional Chinese PharmacyChina Pharmaceutical UniversityNanjing 210009China Jiangsu CM Clinical Medicine Innovation Center for Obstetrics Gynecologyand ReproductionAffiliated Hospital of Nanjing University of Chinese MedicineNanjing 210001China National Institute of Biological Sciences Beijing 102206China Jiangsu Engineering Research Center for Efficient Delivery System of TCM School of PharmacyNanjing University of Chinese MedicineNanjing 210023China

Bile acids(BAs)are synthesized by the host liver from cholesterol and are delivered to the intestine,where they undergo further metabolism by gut microbes and circulate between the liver and intestines through various *** serve to emulsify dietary lipids and act as signaling molecules,regulating the host’s metabolism and immune homeostasis through specific ***,disruptions in BA metabolism,transport,and signaling are closely associated with cholestasis,metabolic disorders,autoimmune diseases,and *** triterpenoids and steroids share structural similarities with BAs,and they have been found to modulate BA metabolism,transport,and signaling,potentially exerting pharmacological ortoxicological ***,we have updated the research progress on BA,with a particular emphasis on new-found microbial ***,the latest advancements in targeting BA metabolism and signaling for disease treatment are ***,the roles of botanical triterpenoids in BA metabolism,transport,and signaling are examined,analyzing their potential pharmacological,toxicological,or drug interaction effects through these ***,a research paradigm is proposed that utilizes the gut microbiota as a link to interpret the role of these important natural products in BA signaling.

关键词： Bile acid Triterpenoid Phytosterol Saponin Gut microbes Cholestasis Metabolic disorders Rheumatoid arthritis

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