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Remote sensing experiments for earth system science

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International Journal of Digital Earth 2021年第10期14卷 1237-1242页

作者： Tianjie Zhao Michael H.Cosh Alexandre Roy xihan mu Yubao Qiu Jiancheng Shi Aerospace Information Research Institute Chinese Academy of SciencesBeijingPeople’s Republic of China USDA-Agricultural Research Service Beltsville Agricultural Research CenterHydrology and Remote Sensing LaboratoryBeltsvilleMDUSA Universitédu QuébecàTrois-Rivières QuébecCanada Faculty of Geographical Science Beijing Normal UniversityBeijingPeople’s Republic of China National Space Science Center Chinese Academy of SciencesBeijingPeople’s Republic of China

The Earth system is an integrated system that can be divided into six main subsystems:geosphere,atmosphere,hydrosphere,cryosphere,biosphere,and *** subsystems are interconnected through the flows of global energy,water,and carbon,which are fundamental constituent cycles within the Earth *** improve our predictive understanding of the subsystem on our changing planet,there is a need to better represent these subsystems through modelling and *** central role of these fundamental cycles has prompted scientific institutions or meteorological centers to develop digital platforms dedicated to the integration,modelling,and assimilation of Earth observation data,e.g.,Big Earth Data Science Engineering(Guo,Li,and Qiu 2020).

关键词： system earth prompt

Quantitative Evaluation of Leaf Inclination Angle Distribution on Leaf Area Index Retrieval of Coniferous Canopies

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Journal of Remote Sensing 2021年第1期2021卷 1-15页

作者： Guangjian Yan Hailan Jiang Jinghui Luo xihan mu Fan Li Jianbo Qi Ronghai Hu Donghui Xie Guoqing Zhou State Key Laboratory of Remote Sensing Science Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China Southwest China Research Institute of Electronic Equipment Chengdu 610036China Guilin University of Technology Guilin 532100China

Both leaf inclination angle distribution(LAD)and leaf area index(LAI)dominate optical remote sensing *** G-function,which is a function of LAD and remote sensing geometry,is often set to 0.5 in the LAI retrieval of coniferous canopies even though this assumption is only valid for spherical *** uncertainties are thus ***,because numerous tiny leaves grow on conifers,it is nearly impossible to quantitatively evaluate such uncertainties in LAI *** this study,we proposed a method to characterize the possible change of G-function of coniferous canopies as well as its effect on LAI ***,a multi-Directional Imager(MDI)was developed to capture stereo images of the branches,and the needles were *** accuracy of the inclination angles calculated from the reconstructed needles was ***,we analyzed whether a spherical distribution is a valid assumption for coniferous canopies by calculating the possible range of the G-function from the measured LADs of branches of Larch and Spruce and the true G-functions of other species from some existing inventory data and threedimensional(3D)tree *** show that the constant G assumption introduces large errors in LAI retrieval,which could be as large as 53%in the zenithal viewing direction used by spaceborne *** a result,accurate LAD estimation is *** the absence of such data,our results show that a viewing zenith angle between 45 and 65 degrees is a good choice,at which the errors of LAI retrieval caused by the spherical assumption will be less than 10%for coniferous canopies.

关键词： distribution function viewing

High Spatial Resolution and High Temporal Frequency(30-m/15-day) Fractional Vegetation Cover Estimation over China Using multiple Remote Sensing Datasets:Method Development and Validation

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Journal of Meteorological Research 2021年第1期35卷 128-147页

作者： xihan mu Tian ZHAO Gaiyan RUAN Jinling SONG Jindi WANG Guangjian YAN Tim RMCVICAR Kai YAN Zhan GAO Yaokai LIU Yuanyuan WANG State Key Laboratory of Remote Sensing Science Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China Beijing Engineering Research Center for Global Land Remote Sensing Products Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China CSIRO Land and Water ACT2601Australia Department of Earth and Environment Boston UniversityBostonMA 02215USA Jiangsu Institute of Urban Planning and Design Nanjing 210036China Aerospace Information Research Institute Chinese Academy of SciencesBeijing 100094China National Satellite Meteorological Center China Meteorological AdministrationBeijing 100081China

High spatial resolution and high temporal frequency fractional vegetation cover(FVC) products have been increasingly in demand to monitor and research land surface processes. This paper develops an algorithm to estimate FVC at a 30-m/15-day resolution over China by taking advantage of the spatial and temporal information from different types of sensors: the 30-m resolution sensor on the Chinese environment satellite(HJ-1) and the 1-km Moderate Resolution Imaging Spectroradiometer(MODIS). The algorithm was implemented for each main vegetation class and each land cover type over China. First, the high spatial resolution and high temporal frequency normalized difference vegetation index(NDVI) was acquired by using the continuous correction(CC) data assimilation method. Then, FVC was generated with a nonlinear pixel unmixing model. Model coefficients were obtained by statistical analysis of the MODIS NDVI. The proposed method was evaluated based on in situ FVC measurements and a global FVC product(GEOV1 FVC). Direct validation using in situ measurements at 97 sampling plots per half month in 2010 showed that the annual mean errors(MEs) of forest, cropland, and grassland were-0.025, 0.133, and 0.160, respectively, indicating that the FVCs derived from the proposed algorithm were consistent with ground measurements [R2 = 0.809,root-mean-square deviation(RMSD) = 0.065]. An intercomparison between the proposed FVC and GEOV1 FVC demonstrated that the two products had good spatial–temporal consistency and similar magnitude(RMSD approximates 0.1). Overall, the approach provides a new operational way to estimate high spatial resolution and high temporal frequency FVC from multiple remote sensing datasets.

关键词： fractional vegetation cover(FVC) high spatial resolution and high temporal frequency data fusion normalized difference vegetation index(NDVI) pixel unmixing model multiple remote sensing datasets

基于多时相GF-6遥感影像的水稻种植面积提取

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农业工程学报 2021年第17期37卷 189-196页

作者：张悦琦李荣平穆西晗任鸿瑞太原理工大学测绘科学与技术系太原030024 北京师范大学遥感科学国家重点实验室北京100875 中国气象局沈阳大气环境研究所沈阳110166

为获取高精度水稻种植面积提取方法和分析红边信息在作物识别能力上的优越性,该研究选取辽宁省盘锦市为研究区域,利用2020年水稻关键物候期的多时相高分6号宽幅相机(GF-6 WFV)遥感影像,构建归一化植被指数(Normalized Difference Vegeta... 详细信息

为获取高精度水稻种植面积提取方法和分析红边信息在作物识别能力上的优越性,该研究选取辽宁省盘锦市为研究区域,利用2020年水稻关键物候期的多时相高分6号宽幅相机(GF-6 WFV)遥感影像,构建归一化植被指数(Normalized Difference Vegetation Index,NDVI)、归一化水体指数(Normalized Difference Water Index,NDWI)、比值植被指数(Ratio Vegetation Index,RVI)和归一化差异红边1指数(Normalized Difference Red-Edge 1 Index,NDRE1),根据各地物类型进行时序分析,在获得水稻面积粗提取结果的基础上对其他地类进行掩膜,准确提取水稻种植面积。对2020年盘锦市水稻提取结果进行精度分析,结果表明,基于实测数据进行精度验证的总体精度为94.44%,基于目视解译数据进行精度验证的总体精度和Kappa系数分别为95.60%和0.91。根据目视解译数据对有无红边波段参与的水稻提取结果进行对比分析可知,红边波段的引入使总体分类精度、水稻制图精度和Kappa系数分别提高了3.20个百分点、6.00个百分点和0.06。该研究证明红边波段可以有效降低作物的错分、漏分情况,对水稻精准估产和丰富农作物遥感监测方法具有重要作用,显示出国产红边卫星数据在作物分类、面积提取方面具有巨大应用潜力。

关键词：遥感作物分类面积提取水稻高分六号卫星红边波段

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规则林地覆盖度照相测量法的精度分析

农业工程学报 2013年第19期29卷 152-158页

作者：赵继强谢东辉孟夏穆西晗阎广建北京师范大学地理学与遥感科学学院遥感科学国家重点实验室北京100875

为定量研究照相法测量规则林地覆盖度中采样策略、相机非垂直拍摄等因素对覆盖度计算结果的影响,该文对河北怀来的一片梨树林进行了实地测量,通过对测量数据的统计计算,利用植被结构生成软件Onyx tree professional重建梨树林场景,采用... 详细信息

为定量研究照相法测量规则林地覆盖度中采样策略、相机非垂直拍摄等因素对覆盖度计算结果的影响,该文对河北怀来的一片梨树林进行了实地测量,通过对测量数据的统计计算,利用植被结构生成软件Onyx tree professional重建梨树林场景,采用基于物理的光线追踪算法模拟相机拍摄的照片,提出了规则林地覆盖度照相法测量的采样方案,并通过计算机模拟检验了采样方案。通过精确控制模拟相机的拍摄条件,进一步分析了非垂直拍摄对测量精度的影响。结果表明,相机的非竖直拍摄对覆盖度计算结果的精度有较大的影响,误差最大可达27.9%。该文提出的测量方案为规则林地的覆盖度实地测量提供了参考。

关键词：遥感采样方案。计算机模拟覆盖度照相法

基于计算机模拟模型LESS的落叶松林木质元素影响分析

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遥感学报 2021年第5期25卷 1138-1151页

作者：许月谢东辉漆建波阎广建穆西晗张吴明北京师范大学地理科学学部遥感科学与工程研究院遥感科学国家重点实验室北京100875 北京林业大学省部共建森林培育与保护教育部重点实验室北京100083

目前大部分植被辐射传输模型在模拟太阳辐射与植被之间的相互作用过程时,将植物结构进行了简化,只保留了叶片的结构和空间分布特征,而忽略了木质元素(枝干等)对冠层反射特性的影响。计算机模拟模型LESS能够充分考虑植被的多种组分光谱... 详细信息

目前大部分植被辐射传输模型在模拟太阳辐射与植被之间的相互作用过程时,将植物结构进行了简化,只保留了叶片的结构和空间分布特征,而忽略了木质元素(枝干等)对冠层反射特性的影响。计算机模拟模型LESS能够充分考虑植被的多种组分光谱和结构特征,精确模拟植被冠层内部的光散射和辐射过程。本文以地面实测数据为基础,发展了以单木为基本单元的复杂森林三维场景重建基本流程;并在重建森林场景基础上,利用计算机模拟模型LESS模拟森林三维场景反射率,对比分析了森林木质元素对冠层反射率的影响。结果表明,忽略木质元素会引起植被冠层反射率模拟的偏差,特别是在近红外波段,在不同叶面积指数(LAI)下,其相对偏差都在40%以上。高空间分辨率是一个会突出木质元素影响的重要因素,随着空间分辨率提高,偏差也随之增大。不同等级枝干结构均对冠层反射率产生影响,即使忽略最小分枝也会引起17.7%(近红外)的估计误差。因此,在进行定量遥感研究中,必须考虑到忽略木质元素引起的偏差,即使是高LAI森林也无法忽视木质元素的影响。特别是在高分辨率遥感图像中,传统的以统计特征代替三维结构分布的辐射传输模型已经无法满足精度的要求。

关键词：辐射传输模型森林反射率木质元素三维重建 LESS

Traveling Wave Characteristics Based Pilot Protection Scheme for Hybrid Cascaded HVDC Transmission Line

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Journal of Modern Power Systems and Clean Energy 2024年第3期12卷 971-980页

作者： Dalin mu Sheng Lin Xiaopeng Li the School of Electrical Engineering Southwest Jiaotong UniversityChengdu 611756China the State Grid Sichuan Electric Power Research Institute Chengdu 610041China

The hybrid cascaded high-voltage direct current(HVDC)transmission system has various operation modes,and some operation modes have sharply increasing requirements for protection rapidity,while the traditional pilot differential protection(PDP)has poor rapidity,and even refuses to operate when faults occur on the DC ***,a novel pilot protection scheme based on traveling wave characteristics is ***,the adaptability of the traditional PDP applied in engineering is analyzed for different operation ***,the expressions of the forward traveling wave(FTW)and backward traveling wave(BTW)on the rectifier side and the inverter side are derived for different fault *** the theoretical derivation,the difference between the BTW and FTW on the rectifier side is less than zero,and the same is true on the inverter ***,in the event of an external fault of DC line,the difference between the BTW and FTW at nearfault terminal protection installation point is greater than ***,by summing over the product of the difference between BTW and FTW of the rectifier side and that of the inverter side,the fault identification criterion is *** simulation results show that the proposed pilot protection scheme can quickly and reliably identify the short-circuit faults of DC line in different operation modes.

关键词： Hybrid cascaded high-voltage direct current(HVDC)transmission system DC line operation mode pilot protection

An optimization-oriented modeling approach using input convex neural networks and its application on optimal chiller loading

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Building Simulation 2024年第4期17卷 639-655页

作者： Shanshuo Xing Jili Zhang Song mu Dalian University of Technology Dalian116024China Guangdong Airport Baiyun Information Technology Co. Ltd.Guangzhou510000China

Optimization for the multi-chiller system is an indispensable approach for the operation of highly efficient chiller *** optima obtained by model-based optimization algorithms are dependent on precise and solvable objective *** classical neural networks cannot provide convex input-output mappings despite capturing impressive nonlinear fitting capabilities,resulting in a reduction in the robustness of model-based *** this paper,we leverage the input convex neural networks(ICNN)to identify the chiller model to construct a convex mapping between control variables and the objective function,which enables the NN-based OCL as a convex optimization problem and apply it to multi-chiller optimization for optimal chiller loading(OCL).Approximation performances are evaluated through a four-model comparison based on an experimental data set,and the statistical results show that,on the premise of retaining prior convexities,the proposed model depicts excellent approximation power for the data set,especially the unseen ***,the ICNN model is applied to a typical OCL problem for a multi-chiller system and combined with three types of optimization *** with conventional and meta-heuristic methods,the numerical results suggest that the gradient-based BFGS algorithm provides better energy-saving ratios facing consecutive cooling load inputs and an impressive convergence speed.

关键词： chiller plant input convex neural network optimal load distribution convex optimization

Strong synergy between physical and chemical properties:Insight into optimization of atomically dispersed oxygen reduction catalysts

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Journal of Energy Chemistry 2024年第4期91卷 36-49页

作者： Yifan Zhang Linsheng Liu Yuxuan Li Xueqin mu Shichun mu Suli Liu Zhihui Dai School of Chemistry and Molecular Engineering Nanjing Tech UniversityNanjing 211816JiangsuChina State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology InstitutionWuhan 430070HubeiChina School of Chemistry and Materials Science Nanjing Normal UniversityNanjing 210023JiangsuChina

Atomically dispersed catalysts exhibit significant influence on facilitating the sluggish oxygen reduction reaction(ORR)kinetics with high atom economy,owing to remarkable attributes including nearly 100%atomic utilization and exceptional catalytic ***,accurately controlling atomic physical properties including spin,charge,orbital,and lattice degrees of atomically dispersed catalysts can realize the optimized chemical properties including maximum atom utilization efficiency,homogenous active centers,and satisfactory catalytic performance,but remains ***,through physical and chemical insight,we review and systematically summarize the strategies to optimize atomically dispersed ORR catalysts including adjusting the atomic coordination environment,adjacent electronic orbital and site density,and the choice of dual-atom *** the emphasis is on the fundamental understanding of the correlation between the physical property and the catalytic behavior for atomically dispersed ***,an overview of the existing challenges and prospects to illustrate the current obstacles and potential opportunities for the advancement of atomically dispersed catalysts in the realm of electrocatalytic reactions is offered.

关键词： Atomically dispersed catalysts Coordination environment Electronic orbitals Inter-site distance effect Oxygen reduction reaction