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Research on scale effect of histogram

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Science China Earth Sciences 2002年第10期45卷 949-960页

作者：张颢李小文阎广建焦子锑王锦地赵红蕊杨华苏理宏 1. Research Center for remote sensing and GIS Department of Geography and Beijing Key Laboratory for Remote Sensing of Environment and Digital Cities Beijing Normal University 100875 Beijing China 2. Center for remote sensing and department of Geography Boston University 02215 MA USA

To describe the spatial relationship among the earth objects compactly, in this paper, we raised the concept of histo-variogram based on the analysis of the characteristics of other spatial analyzing methods such as variogram, information entropy. And we also raised a new spatial analysis method of histogram decomposition based on the definition of standing pixel and contour pixel. At the end of this paper, we demonstrated the characteristics of histo-variogram by two experiments, one for spatial analysis, the other for image fusion.

关键词： histo-variogram, scaling, histogram-decomposition, standing-pixel, HIS transform.

Interferometric orbit determination for geostationary satellites

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Science China(Information Sciences) 2017年第6期60卷 22-32页

作者： Roger M.FUSTER Marc FERNNDEZ USóN Antoni BROQUETAS IBARS remote sensing Laboratory Department of Signal and Communications TheoryUniversitat Politècnica de Catalunya

Future Geo SAR missions are expected to provide higher resolution radar images featuring shorter revisit times by locating a radar payload on-board of a geostationary satellite. One of the main challenges in Geo SAR processing is accurately determining the satellite orbit to obtain a precise phase history, in order to properly focus the retrieved data. To tackle this challenge, a multiple baseline ground-based interferometer is proposed as a compact and reliable method to achieve an unprecedented accuracy. As a proof of concept, this paper presents the results obtained from a single baseline prototype, whose results can be extrapolated to a larger system, able to be used in future missions.

关键词： GeoSAR interferometry orbit determination geostationary SAR

Microwave Doppler spectra of sea return at small incidence angles:specular point scattering contribution

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Chinese Physics B 2010年第8期19卷 384-390页

作者：张彦敏王运华赵朝方 department of Physics Ocean University of China Ocean remote sensing Institute Ocean University of China

It is well known that the sea return echo contains contributions from at least two scattering mechanisms. In addition to the resonant Bragg scattering, the specular point scattering plays an important role as the incidence angle becomes smaller （≥ 20°）. Here, in combination with the Kirchhoff integral equation of scattering field and the stationary phase approximation, analytical expressions for Doppler shift and spectral bandwidth of specular point scattering, which are insensitive to the polarization state, are derived theoretically. For comparison, the simulated results related to the two-scale method （TSM） and the method of moment （MOM） are also presented. It is found that the Doppler shift and the spectral bandwidth given by TSM are insufficient at small incidence angles. However, a comparison between the analytical results and the numerical simulations by MOM in the backscatter configuration shows that our proposed formulas are valid for the specular point scattering case. In this work, the dependences of the predicted results on incidence angle, radar frequency, and wind speed are also discussed. The obtained conclusions seem promising for a better understanding of the Doppler spectra of the specular point scattering fields from time-varying sea surfaces.

关键词： Doppler spectrum specular point scattering sea surface Kirchhoff approximation

Synchronous estimation of DTM and fractional vegetation cover in forested area from airborne LIDAR height and intensity data

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Science China(Technological Sciences) 2008年第S2期51卷 176-187页

作者： BAO YunFei1,2,CAO ChunXiang1,ZHANG Hao1,CHEN ErXue3,HE QiSheng1,2,HUANG HuaBing1,LI ZengYuan3,LI XiaoWen1,4 & GONG Peng1 1 State Key Laboratory of remote sensing Science,jointly sponsored by the Institute for remote sensing Applications of Chinese Academy of Sciences and Beijing Normal University,Beijing 100101,China 2 Graduate University of the Chinese Academy of Sciences,Beijing 100049,China 3 Institute of Forest resource Information Technique,the Chinese Academy of Forestry,Beijing 100091,China 4 Research Center for remote sensing and GIS,department of Geography and Beijing Key Laboratory for remote sensing of Environment and Digital Sites,Beijing Normal University,Beijing 100875,China State Key Laboratory of remote sensing Science jointly sponsored by the Institute for Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University Beijing 100101 China Graduate University of the Chinese Academy of Sciences Beijing 100049 China Institute of Forest resource Information Technique the Chinese Academy of Forestry Beijing 100091 China Research Center for remote sensing and GIS Department of Geography and Beijing Key Laboratory for Remote Sensing of Environment and Digital Sites Beijing Normal University Beijing 100875 China

We proposed a method to separate ground points and vegetation points from discrete return,small footprint airborne laser scanner data,called skewness change *** method,which makes use of intensity of laser scanner data,is especially applicable in steep,and forested *** does not take slope of forested area into account,while other algorithms consider the change of slope in steep forested *** ground points and vegetation points can be used to estimate digital terrain model(DTM) and fractional vegetation cover,respectively.A few vegetation points which were classified into the ground points were removed as noise before the generation of *** method was tested in a test area of 10000 square meters.A LiteMapper -5600 laser system was used and a flight was carried out over a ground of 700―800 *** this tested area,a total number of 1546 field measurement ground points were measured with a total station TOPCON GTS-602 and TOPCON GTS -7002 for validation of DTM and the mean error value is -18.5 cm and the RMSE(root mean square error) is ±20.9 cm.A data trap sizes of 4m in diameter from airborne laser scanner data was selected to compute vegetation fraction *** of fractional vegetation cover was carried out using 15 hemispherical photographs,which are georeferenced to centimeter accuracy by differential *** gap fraction was computed over a range of zenith angles 10° using the gap light analyzer(GLA) from each hemispherical *** R2 for the regression of fractional vegetation cover from these ALS data and the respective field measurements is *** this study presents a method for synchronous estimation of DTM and fractional vegetation cover in forested area from airborne LIDAR height and intensity data.

关键词： LIDAR intensity skewness synchronous DTM fractional vegetation cover

LEARNING GRANGER CAUSALITY GRAPHS FOR MULTIVARIATE NONLINEAR TIME SERIES

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Journal of Systems Science and Systems Engineering 2009年第1期18卷 38-52页

作者： Wei GAO Zheng TIAN department of Applied Mathematics Northwest Polytechnical University Xi'an Shanxi 710072 China estate Key Laboratory of remote sensing Science Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing 100101 China

An information theory method is proposed to test the. Granger causality and contemporaneous conditional independence in Granger causality graph models. In the graphs, the vertex set denotes the component series of the multivariate time series, and the directed edges denote causal dependence, while the undirected edges reflect the instantaneous dependence. The presence of the edges is measured by a statistics based on conditional mutual information and tested by a permutation procedure. Furthermore, for the existed relations, a statistics based on the difference between general conditional mutual information and linear conditional mutual information is proposed to test the nonlinearity. The significance of the nonlinear test statistics is determined by a bootstrap method based on surrogate data. We investigate the finite sample behavior of the procedure through simulation time series with different dependence structures, including linear and nonlinear relations.

关键词： Multivariate nonlinear time series Granger causality graph conditional mutual information surrogate data

Evaluation on the Two Filling Functions for the Recovery of Forest Information in Mountainous Shadows on Landsat ETM + Image

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Journal of Mountain Science 2011年第3期8卷 414-426页

作者： SHAHTAHMASSEBI Amir reza MOORE Nathan Institute of Agriculture remote sensing and Information Technology Zhejiang University Key Laboratory of Agricultural remote sensing and Information System of Zhejiang Province department of Geography Michigan State University

In general,topographic shadow may reduce performance of forest mapping over mountainous regions in remotely sensed *** this paper,information in shadow was synthesized by using two filling techniques,namely,roifill and imfill,in order to improve the accuracy of forest mapping over mountainous *** two methods were applied to Landsat Enhanced Thematic Mapper (ETM +) multispectral image from Dong Yang County,Zhejiang Province,*** performance of these methods was compared with two conventional techniques,including cosine correction and multisource *** results showed that by applying filling approaches,average overall accuracy of classification was improved by 14 ***,through conventional methods this value increased only by 9 *** results also revealed that estimated forest area on the basis of shadow-corrected images by 'roifill' technique was much closer to the survey data compared to traditional *** from this finding,our finding indicated that topographic shadow was an accentuated problem in medium resolution images such as Landsat ETM+ over mountainous regions.

关键词： Shadow Imfill: Roifill: Landsat ETM+

Co-loading Pd and CeO_(2)on Silicalite-1 as High-performance Catalyst for Methane Dry Reforming Reaction

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Chemical Research in Chinese Universities 2025年第1期41卷 15-20页

作者： XU Jing ZHANG Rui WANG Ke WANG Xiao SONG Shuyan ZHANG Hongjie State Key Laboratory of Rare Earth resource Utilization Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun130022P.R.China School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei230026P.R.China department of Chemistry Tsinghua UniversityBeijing100084P.R.China

The methane dry reforming(DRM)reaction can convert CO_(2)and CH_(4),both of which contribute to climate change,into syngas,which holds great significance in mitigating specific environmental issues stemming from the greenhouse ***,the challenges that persist include the substantial energy consumption and the catalyst’s susceptibility to deactivation,both of which necessitate ***,we developed a catalyst,PdCe/S1,featuring small-sized Pd species and CeO_(2)stabilized on pure silicon zeolite(silicalite-1),which is employed in the DRM *** can achieve 97%CH_(4)conversion and 98%CO_(2)conversion at 750℃,surpassing binary Pd/CeO_(2)and Pd/S1 *** small size of CeO_(2)stabilized by silicalite-1 promotes oxygen defects formation and enhances the CO_(2)adsorption *** introduction of silicalite-1 further enhances the interaction between Pd and CeO_(2),boosting DRM performance.

关键词： Dry reforming of methane CeO_(2) Zeolite

Multi-criteria decision based geospatial mapping of flood susceptibility and temporal hydro-geomorphic changes in the Subarnarekha basin, India

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Geoscience Frontiers 2021年第5期12卷 327-341页

作者： Sumit Das Amitesh Gupta department of Geography Savitribai Phule Pune UniversityPune 411007India Marine and Atmospheric Science department Indian Institute of Remote Sensing(ISRO)DehradunIndia department of remote sensing and GIS JIS UniversityKolkataIndia

The Subarnarekha River in east India experiences frequent high magnitude flooding in monsoon *** this study,we present an in-depth analysis of flood hydrology and GIS-based flood susceptibility mapping of the entire *** 40 years of annual peak discharge data,historical cross-sections of different gauging sites,and 12 flood conditioning factors were *** flood susceptibility mapping followed an expert knowledge-based multi-parametric analytical hierarchy process(AHP)and optimized AHP-VIP *** hydrology data indicated more than 5 times higher discharge contrasted with the mean streamflow of the peak monsoon month in all hydro-monitoring stations that correspond to possible overbank flooding in the shallow semi-alluvial reaches of the Subarnarekha *** ratio revealed continuous changes on the channel cross-sections at decadal scale in all gauging *** flood susceptibility map through optimized AHP-VIP method showed a great amount of areas(38%)have a high probability of flooding and demands earnest attention of administrative *** AHP-VIP based flood susceptibility map was theoritically validated through AUC approach and it showed fairly high accuracy(AUC=0.93).Our study offers an exceptionally cost and time effective solution to the flooding issues in the Subarnarekha basin.

关键词： Flood susceptibility AHP GIS Discharge Subarnarekha India

Big Earth Data from space: a new engine for Earth science

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Science Bulletin 2016年第7期61卷 505-513页

作者： Huadong Guo Lizhe Wang Dong Liang Institute of remote sensing and Digital Earth Chinese Academy of Sciences

Big data is a strategic highland in the era of knowledge-driven economies, and it is also a new type of strategic resource for all nations. Big data collected from space for Earth observation—so-called Big Earth Data—is creating new opportunities for the Earth sciences and revolutionizing the innovation of methodologies and thought patterns. It has potential to advance in-depth development of Earth sciences and bring more exciting scientific *** Academic Divisions of the Chinese Academy of Sciences Forum on Frontiers of Science and Technology for Big Earth Data from Space was held in Beijing in June of *** forum analyzed the development of Earth observation technology and big data, explored the concepts and scientific connotations of Big Earth Data from space, discussed the correlation between Big Earth Data and Digital Earth, and dissected the potential of Big Earth Data from space to promote scientific discovery in the Earth sciences, especially concerning global changes.

关键词： Big data Big Earth Data from spaceDigital Earth Earth sciences Earth observation Scientific big data Data-intensive science