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Forest terrain and canopy height estimation using stereo images and spaceborne LiDAR data from GF-7 satellite

地球空间信息科学学报（英文版） 2024年第3期27卷 811-821页

作者： Liming Du Yong Pang Wenjian Ni Xiaojun Liang Zengyuan Li Juan Suarez Wei Wei Institute of Forest Resource Information Techniques Chinese Academy of ForestryBeijingChina Key Laboratory of Forestry Remote Sensing and Information System National Forestry and Grassland AdministrationBeijingChina State Key Laboratory of Remote Sensing Science Institute of Remote Sensing and Digital EarthChinese Academy of SciencesBeijingChina College of Resources and Environment University of Chinese Academy of SciencesBeijingChina Forest Research Northern Research StationMidlothianUK Institute of Science and Technology Information Yunnan Academy of Forestry and GrasslandKunmingChina

Accurate estimation of forest terrain and canopy height is crucial for timely understanding of forest *** Fen-7(GF-7)Satellite is China's first sub-meter-level three-dimensional(3D)mapping satellite for civilian use,which was equipped with a two-line-array stereo mapping camera and a laser altimeter system that can provide stereo images and full waveform LiDAR data *** of the existing studies have concentrated on evaluating the accu-racy of GF-7 for topographic survey in bare land,but few have in-depth studied its ability to measure forest terrain elevation and canopy *** purpose of this study is to evaluate the potential of GF-7 LiDAR and stereo image for forest terrain and height *** Airborne Laser Scanning(ALS)data were utilized to generate reference terrain and forest vertical *** validation test was conducted in Pu'er City,Yunnan Province of China,and encouraging results have *** GF-7 LiDAR data obtained the accuracy of forest terrain elevation with RMSE of 8.01 m when 21 available laser footprints were used for results verification;meanwhile,when it was used to calculate the forest height,R2 of 0.84 and RMSE of 3.2 m were obtained although only seven effective footprints were used for result *** canopy height values obtained from GF-7 stereo images have also been proven to have high accuracy with the resolution of 20 m x 20 m compared with ALS data(R2=0.88,RMSE=2.98 m).When the results were verified at the forest sub-compartment scale that taking into account the forest types,further higher accuracy(R2=0.96,RMSE=1.23 m)was *** results show that GF-7 has considerable application potential in forest resources monitoring.

关键词： Gao Fen-7(GF-7) spaceborne LiDAR stereo image Airborne Laser Scanning(ALS) forest height Pu'er

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Multi-objective Optimization of Electromagnetic Launch System Based on Improved RVEA-IGNG Algorithm 1

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19th International Conference of Intelligent Unmanned Systems, ICIUS 2023

作者： Li, Xiaoyu Guo, Ke Chao, Tao Ma, Ping Yang, Ming Wang, Songyan Harbin Institute of Technology Harbin150001 China National Key Laboratory of Modeling and Simulation for Complex Systems Harbin China Beijing Institute of Space Long March Vehicle Beijing100076 China

ISBN: (数字)9789819765911

ISBN: (纸本)9789819765904

For analyzing the influences of discharge sequence of each pulsed power supply and discharge voltage on the performance of the electromagnetic launch system, intelligent optimization algorithms are carried out based on the simulation model of the electromagnetic launch system. Based on the maximum rail current, projectile exit velocity and energy conversion efficiency, the corresponding multi-objective optimization model is established, and the Pareto front (PF) is acquired in RVEA-iGNG algorithm. The algorithm combines an evolutionary optimization algorithm with the reference vector adaptive adjustment by growing neural gas network. It can handle the multi-objective optimization of the electromagnetic launch system with complex irregular PF and achieve fast convergence. In order to provide decision makers with more diversified solutions, this paper proposes an improved RVEA-iGNG algorithm where the archive maintenance strategy is improved. The simulation results not only show that the RVEA-iGNG algorithm can effectively solve the electromagnetic launch system multi-objective optimization problem, but also show that the improved archive maintenance strategy is significantly better than the archive in the original RVEA-iGNG in terms of enhancing the diversity of solutions. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.

关键词： Electromagnetic launchers

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Soil Organic Carbon Changes in City Areas of China Over the Past Three Decades:Implications for Achieving Carbon Neutrality

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Engineering 2023年第9期28卷 11-15页

作者： Zhenrui Zhang Xinghui Xia Zhifeng Yang Key Laboratory of Water and Sediment Sciences of Ministry of Education&State Key Laboratory of Water Environment Simulation School of EnvironmentBeijing Normal UniversityBeijing 100875China Key Laboratory for City Cluster Environmental Safety and Green Development of the Ministry of Education Institute of Environmental and Ecological EngineeringGuangdong University of TechnologyGuangzhou 510006China

The substantial amount of greenhouse gas emissions from anthropogenic activities has caused the global mean surface temperature to increase by 0.99℃since the industrial revolution[1].China is committed to achieving carbon neutrality by 2060 in response to climate change[2].Soil stores approximately 2344–3000 Pg(1015 g)of carbon at depths of 0–100 cm in terrestrial ecosystems,an amount approximately equivalent to twice the amount in the atmospheric carbon pool and three times that in the terrestrial biomass;therefore,even a small change in soil carbon stocks will exert significant impacts on atmospheric CO_(2)concentrations[3].

关键词： stores terrestrial Carbon

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Bilateral Dense Feature Circulation for Small Object Detection 43

Bilateral Dense Feature Circulation for Small Object Detecti...

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43rd Chinese Control Conference, CCC 2024

作者： Duan, Junzhu Li, Fangyu Han, Honggui Beijing University of Technology Faculty of Information Technology Beijing100124 China Beijing University of Technology Beijing Key Laboratory of Computational Intelligence and Intelligent System Beijing100124 China Beijing University of Technology Engineering Research Center of Digital Community Ministry of Education Beijing100124 China Beijing Artificial Intelligence Institute Beijing University of Technology Beijing100124 China

ISBN: (纸本)9789887581581

Object detection is the task of classifying and locating objects. Deep learning-based object detection is the current mainstream, however, detecting small scale targets is still challenging. To achieve accurate detection of small objects, we propose a bilateral dense feature circulation method (BCM). First, to make the network strategically extract features that contain useful location information, we design a bilateral feature circulation module in a dense nested way to detect small objects. Second, in order to fully utilize and fuse each scale feature, we sequentially perform the channel and spatial attention to each layer in the feature fusion stage. Third, through repetitive and progressive feature extraction and fusion under the instruction of the attention module, we attain sufficient information to detect small objects. We conducted experiments on PASCAL VOC and Tsinghua-Tencent 100k. The experiment results show that the proposed model improves the mAP of small objects on PASCAL VOC by 1.8% and Tsinghua-Tencent 100k by 2.7% compared with SOTA methods. © 2024 Technical Committee on Control Theory, Chinese Association of Automation.

关键词： Feature extraction

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Bioinspired surface functionalization of biodegradable mesoporous silica nanoparticles for enhanced lubrication and drug release

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Friction 2023年第7期11卷 1194-1211页

作者： Xiaowei MAO Kexin CHEN Yanlong ZHAO Chunrong Xiong Jing LUO Yuguang WANG Bo WANG Hongyu ZHANG School of Chemical Engineering and Technology Hainan UniversityHaikou 570228China State Key Laboratory of Tribology Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China Peking University School of Nursing&National Engineering Laboratory for Digital and Material Technology of Stomatology Beijing 100191China Beijing Research Institute of Automation for Machinery Industry Co. Ltd.Beijing 100120China Center of Digital Dentistry Peking University School and Hospital of Stomatology&NHC Research Center of Engineering and Technology for Computerized DentistryBeijing 100081China College of Chemical and Biological Engineering Shandong University of Science and TechnologyQingdao 266590China

Osteoarthritis is associated with the significantly increased friction of the joint,which results in progressive and irreversible damage to the articular cartilage.A synergistic therapy integrating lubrication enhancement and drug delivery is recently proposed for the treatment of early-stage *** the present study,bioinspired by the self-adhesion performance of mussels and super-lubrication property of articular cartilages,a biomimetic self-adhesive dopamine methacrylamide-poly(2-methacryloyloxyethyl phosphorylcholine)(DMA-MPC)copolymer was designed and synthesized via free radical *** copolymer was successfully modified onto the surface of biodegradable mesoporous silica nanoparticles(bMSNs)by the dip-coating method to prepare the dual-functional nanoparticles(bMSNs@DMA-MPC),which were evaluated using a series of surface characterizations including the transmission electron microscope(TEM),Fourier transform infrared(FTIR)spectrum,thermogravimetric analysis(TGA),X-ray photoelectron spectroscopy(XPS),*** tribological test and in vitro drug release test demonstrated that the developed nanoparticles were endowed with improved lubrication performance and achieved the sustained release of an anti-inflammatory drug,i.e.,diclofenac sodium(DS).In addition,the in vitro biodegradation test showed that the nanoparticles were almost completely biodegraded within 10 ***,the dual-functional nanoparticles were biocompatible and effectively reduced the expression levels of two inflammation factors such as interleukin-1β(IL-1β)and interleukin-6(IL-6).In summary,the surface functionalized nanoparticles with improved lubrication and local drug release can be applied as a potential intra-articularly injected biolubricant for synergistic treatment of early-stage osteoarthritis.

关键词： surface functionalization phosphorylcholine coating mesoporous silica nanoparticles hydration lubrication osteoarthritis

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Modeling the dynamic impacts of maritime network blockage on global supply chains

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The Innovation 2024年第4期5卷 103-109,102页

作者： Shen Qu Yunlei She Qi Zhou Jasper Verschuur Lu-Tao Zhao Huan Liu Ming Xu Yi-Ming Wei Center for Energy and Environmental Policy Research Beijing Institute of TechnologyBeijing 100081China School of Management Beijing Institute of TechnologyBeijing 100081China Beijing Key Lab of Energy Economics and Environmental Management Beijing 100081China Oxford Programme for Sustainable Infrastructure Systems(OPSIS) Environmental Change InstituteUniversity of OxfordOX12JD OxfordUK State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex Beijing 100084China School of Environment Tsinghua UniversityBeijing 100084China

Recent phenomena such as pandemics,geopolitical tensions,and climate change-induced extreme weather events have caused transportation network interruptions,revealing vulnerabilities in the global supply chain.A salient example is the March 2021 Suez Canal blockage,which delayed 432 vessels carrying cargo valued at$92.7 billion,triggering widespread supply chain *** ability to model the spatiotemporal ramifications of such incidents remains *** fill this gap,we develop an agent-based complex network model integrated with frequently updated maritime *** Suez Canal blockage is taken as a case *** results indicate that the effects of such blockages go beyond the directly affected countries and *** Suez Canal blockage led to global losses of about$136.9($127.5–$147.3)billion,with India suffering 75%of these *** losses show a nonlinear relationship with the duration of blockage and exhibit intricate trends post *** proposed model can be applied to diverse blockage scenarios,potentially acting as an earlyalert system for the ensuing supply chain ***,high-resolution daily data post blockage offer valuable insights that can help nations and industries enhance their resilience against similar future events.

关键词： chains valued extreme

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A tantalum-containing zirconium-based metallic glass with superior endosseous implant relevant properties

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Bioactive Materials 2024年第9期39卷 25-40页

作者： Yunshu Wu Feifei Wang Yao Huang Fu Zheng Yuhao Zeng Zhen Lu Songlin Wang Baoan Sun Yuchun Sun Center of Digital Dentistry Peking University School and Hospital of StomatologyBeijing100081China National Clinical Research Center for Oral Diseases&National Engineering Research Center of Oral Biomaterials and Digital Medical Devices Beijing100081China Beijing Key Laboratory of Digital Stomatology Beijing100081China Beijing Laboratory of Oral Health Capital Medical UniversityBeijing100069China Institute of Physics Chinese Academy of SciencesBeijing100190China Department of Orthodontics Peking University School and Hospital of StomatologyBeijing100081China Laboratory of Homeostatic Medicine School of MedicineSouthern University of Science and TechnologyShenzhen518055China

Zirconium-based metallic glasses(Zr-MGs)are demonstrated to exhibit high mechanical strength,low elastic modulus and excellent biocompatibility,making them promising materials for endosseous ***,tantalum(Ta)is also well known for its ideal corrosion resistance and biological ***,the metal has an elastic modulus as high as 186 GPa which is not comparable to the natural bone(10–30 GPa),and it also has a relative high ***,to fully exploit the advantages of Ta as endosseous implants,a small amount of Ta(as low as 3 at.%)was successfully added into a Zr-MG to generate an advanced functional endosseous implant,Zr58Cu25Al14Ta3 MG,with superior comprehensive *** carefully dissecting the atomic structure and surface chemistry,the results show that amorphization of Ta enables the uniform distribution in material surface,leading to a significantly improved chemical stability and extensive material-cell contact *** analyses on the immunological,angiogenesis and osteogenesis capability of the material are carried out utilizing the next-generation sequencing,revealing that Zr_(58)Cu_(25)Al_(14)Ta_(3)MG can regulate angiogenesis through VEGF signaling pathway and osteogenesis via BMP signaling *** experiment further confirms a sound osseointegration of Zr_(58)Cu_(25)Al_(14)Ta_(3)MG in achieving better bone-implant-contact and inducing faster periimplant bone formation.

关键词： Tantalum Zirconium-based metallic glass Surface chemistry Atomic structure Endosseous implant

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A low Mach number asymptotic analysis of dissipation-reducing methods for curing shock instability

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Applied Mathematics and Mechanics(English Edition) 2025年第4期46卷 723-744页

作者： Hongping GUO Xun WANG Zhijun SHEN National Key Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsBeijing100088China Faculty of Mathematics Baotou Teachers’CollegeBaotouInner Mongolia Autonomous Region014030China School of Mathematical Sciences Peking UniversityBeijing100871China PKU-Changsha Institute for Computing and Digital Economy Changsha410205China Center for Applied Physics and Technology Peking UniversityBeijing100871China

We are intrigued by the issues of shock instability,with a particular emphasis on numerical schemes that address the carbuncle phenomenon by reducing dissipation rather than increasing *** a specific class of planar flow fields where the transverse direction exhibits vanishing but non-zero velocity components,such as a disturbed onedimensional(1D)steady shock wave,we conduct a formal asymptotic analysis for the Euler system and associated numerical *** analysis aims to illustrate the discrepancies among various low-dissipative numerical ***,a numerical stability analysis of steady shock is undertaken to identify the key factors underlying shock-stable *** verify the stability mechanism,a consistent,low-dissipation,and shock-stable HLLC-type Riemann solver is presented.

关键词： Riemann solver numerical shock instability low Mach number HLLC

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In Situ 3D Scene Synthesis for Ubiquitous Embodied Interfaces 24

In Situ 3D Scene Synthesis for Ubiquitous Embodied Interface...

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32nd ACM International Conference on Multimedia, MM 2024

作者： Jiang, Haiyan Song, Leiyu Weng, Dongdong Sun, Zhe Li, Huiying Dongye, Xiaonuo Zhang, Zhenliang Beijing Institute of Technology Beijing China School of Animation and Digital Arts Communication University of China Beijing China State Key Laboratory of General Artificial Intelligence Beijing Institute for General Artificial Intelligence Beijing China

ISBN: (纸本)9798400706868

Virtual reality enables us to access and interact with immersive virtual environments anytime and anywhere in various fields such as entertainment, training, and education. However, users immersed in virtual scenes remain physically connected to their real-world surroundings, which can pose safety and immersion challenges. Although virtual scene synthesis has attracted widespread attention, many popular methods are limited to generating purely virtual scenes independent of physical environments or simply mapping physical objects as obstacles. To this end, we propose a scene agent that synthesizes situated 3D virtual scenes as a kind of ubiquitous embodied interface in VR for users. The scene agent synthesizes scenes by perceiving the user's physical environment as well as inferring the user's demands. The synthesized scenes maintain the affordances of the physical environment, enabling immersive users to interact with the physical environment and improving the user's sense of security. Meanwhile, the synthesized scenes maintain the style described by the user, improving the user's immersion. The comparison results show that the proposed scene agent can synthesize virtual scenes with better affordance maintenance, scene diversity, style maintenance, and 3D intersection over union compared to baselines. To the best of our knowledge, this is the first work that achieves in situ scene synthesis with virtual-real affordance consistency and user demand. © 2024 ACM.

关键词： Virtual environments

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Multi-scale variability of internal solitary wave speed in the Sulu Sea

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Journal of Oceanology and Limnology 2025年第3期43卷 709-722页

作者： Xixi LI Jianjun LIANG Kaiguo FAN Xiao-Ming LI Key Laboratory of Digital Earth Science Aerospace Information Research InstituteChinese Academy of SciencesBeijing 100094China Key Laboratory of Earth Observation of Hainan Province Hainan Aerospace Information Research InstituteWenchang 571333China International Research Center of Big Earth Data for Sustainable Development Goals Beijing 100094China School of Meteorology and Oceanography National University of Defense TechnologyChangsha 410015China University of Chinese Academy of Sciences Beijing 100049China

Internal solitary waves(ISWs)have considerable energy to drive the mixing of water masses in the Sulu *** propagation speed is one of the critical parameters in quantifying the energy budget of the *** collected 1354 groups of ISWs’speeds from tandem satellite remote sensing images with temporal intervals shorter than 25 min and analyzed their spatial and multi-scale temporal variations in the Sulu *** found that water depth plays an important role in modulating the spatial variation of wave speeds,which increase exponentially with water depth with a power of *** currents,ocean stratification,background circulation,and climate affect the temporal variations of wave speeds from days to months or *** fortnightly spring/neap tidal currents cause daily variations of wave speeds up to 40%by modulating the ISW *** addition to the well-accepted results that monthly variations of wave speeds are related to density stratification,we found that enhanced stratification increases wave speeds,and the background circulation leads to a maximum decrease of 0.27 m/s in the linear counterparts of wave ***,the averaged wave speed collected in October is lower than the corresponding linear one possibly due to some unknown dynamical processes or underestimation of background *** for the interannual variations,we show that wave speed increases in La Niña years and decreases in El Niño years as a result of the climatic modulation on the depth of the maximum value of buoyancy frequency.

关键词： internal solitary wave(ISW) tidal current circulation current El Niño-Southern Oscillation(ENSO) Sulu Sea

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