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Monitoring of rice crop using ENVISAT ASAR data

Science china Earth Sciences 2006年第7期49卷 755-763页

作者： DONG Yanfang1, 2, SUN Guoqing1,3 & PANG Yong4 1. State Key Laboratory of Remote Sensing Science, institute of Remote Sensing Applications, chinese academy of Sciences, beijing 100101, china 2. Graduate University of chinese academy of Sciences, beijing 100039, china 3. Department of Geography, University of Maryland, College Park, MD 20742, USA 4. forest Remote Sensing Lab, research institute of forest resource and information technology, chinese academy of for-estry, beijing 100091, china State Key Laboratory of Remote Sensing Science Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing China Graduate University of chinese academy of Sciences Beijing China Department of Geography University of Maryland College Park USA forest Remote Sensing Lab Research Institute of Forest Resource and Information Technology Chinese Academy of Forestry Beijing China

Because of the cloudy conditions during the rice growth period, rice is one of the agri-cultural crops most suited to monitoring with the SAR instruments. Backscatter response measured by SAR is correlated with rice conditions, including height, density, biomass and structure, which are variable at different growing stages. In this paper, multi-date ENVISAT ASAR Alternating Polarization Mode (APMode) imageries were acquired during the rice crop growing cycle. At the same time, the rice parameters were measured in field. A continuous canopy model was used to compute the back-scattering from rice fields during the growth cycle, and the relationship between rice parameters and radar backscattering coefficients from both ASAR and modeling was analyzed. The effects of polari-zation, incidence angle and polarization on radar backscattering coefficients were analyzed. It was found that simulated radar backscatter has similar trends as ASAR data. This will be meaningful for the further research of rice parameters estimation from ASAR data. Different features show signifi-cantly different signatures in ASAR images and they follow some certain laws, so rice area can be accurately mapped by using multi-temporal SAR images, then rice yield can be estimated.

关键词： rice, ASAR, radar backscattering, model.

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Digital forestry research in china

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Science china(Technological Sciences) 2006年第Z1期49卷 1-8页

作者： TANG Shouzheng, TANG Una, Guofan Shao & DAI Limin research institute of resource information Techniques, chinese academy of forestry, beijing 100091, china institute of Applied Ecology, chinese academy of Sciences, Shenyang 110016, china Departmet of forestry and Natural resources, Purdue University, West Lafayette, IN 47907, USA Graduate University, chinese academy of Sciences, beijing 100101, china research institute of resource information Techniques Chinese Academy of Forestry Beijing China institute of Applied Ecology Chinese Academy of Sciences Shenyang China Graduate University Chinese Academy of Sciences Beijing China Department of forestry and Natural resources Purdue University West Lafayette USA

Digital forestry as a concept was developed after the Digital Earth program. The chinese scientists were not only among the pioneers who first proposed the concept of Digital forestry, but also contributed a lot to the development of Digital forestry. Digital forestry is a digital framework to maintain forest planting, management, using, and protect. The synergetic use of computationally-intensive quantitative methods together with information technologies is the most important foundation for the development of Digital forestry. Under this situation, the experience of Digital forestry development in china is relatively rich. A number of academicians, scholars, and professional administrators were involved in discussing the Digital forestry Construction Scheme. The Project of Digital forestry Practicability approved by the State forestry Administration is a major instance in developing Digital forestry standard and key techniques. By introducing a case study of Digital forestry, this paper reviews the concept of Digital forestry, the way turning traditional forestry into Digital forestry, and the future development of Digital forestry.

关键词： Digital forest, Digital Earth, Digital forestry standard, Digital forestry techniques.

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Analysis of forest backscattering characteristics based on polarization coherence tomography

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Science china(Technological Sciences) 2010年第S1期53卷 166-175页

作者： LUO HuanMin 1,LI XiaoWen 1,2,CHEN ErXue 3,CHENG Jian 4 & CAO ChunXiang 21 institute of Geo-Spatial information Science and technology,University of Electronic Science and technology of china,Chengdu 610054,china 2 State Key Laboratory of Remote Sensing Science,Jointly Sponsored by the institute of Remote Sensing Applications of chinese academy of Sciences and beijing Normal University,beijing 100101,china 3institute of forest {{14.s information Technique of chinese academy of forestry,beijing 100091,china 4 School of Electronic Engineering,University of Electronic Science and technology of china,Chengdu 610054,china institute of Geo-Spatial information Science and technology University of Electronic Science and Technology of China Chengdu China State Key Laboratory of Remote Sensing Science Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University Beijing China institute of forest resources information Technique of chinese academy of forestry Beijing China School of Electronic Engineering University of Electronic Science and Technology of China Chengdu China

It is difficult to make an inventory of vertical profiles of forest structure parameters in field ***,analysis and understanding of forest backscattering characteristics contribute to estimation and detection of forest vertical structure because of the close relationships between backscattering characteristics and structure *** vertical structure function in the complex interferometric coherence definition,which represents the vertical variation of microwave scattering with the penetration depth at a point in the 2-D radar image and can be used to analyze the forest backscattering characteristics,can be reconstructed from polarization coherence tomography(PCT).Based on PCT,the paper analyzes the forest backscattering characteristics and explores the inherent relationship between the result of PCT and the forest structure parameters from numerical simulation of Random Volume over Ground model(RVoG),Polarimetric SAR interferometry(PolInSAR)simulation of forest scene and PolInSAR data at L-band of the test site ***,the effects of the extinction coefficient and surface-to-volume scattering ratio in RVoG model on vertical backscattering characteristics are analyzed by means of numerical ***,by applying PCT to L-band POLInSAR simulations of forest scene,different variations of vertical backscattering due to different extinction coefficients and the ratios of surface-to-volume scattering resulting from different polarizations,forest types and densities are displayed and *** a concept of relative average backscattering intensity is presented,and the factors which affect its vertical distribution are also *** results show that there is high sensitivity of the vertical distribution of forest relative average backscattering intensity to the polarization,forest type and ***,based on repeat pass DLR E-SAR L-band airborne POLInSAR data,the capability of PCT technology for detection

关键词： backscattering characteristic POLInSAR PCT vertical structure function

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Threat and management strategies of potentially invasive insects in china

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Science china(Life Sciences) 2009年第10期52卷 903-910页

作者： ZHANG RunZhi1, ZHANG YaPing2 & JIANG YouXu3 1 State Key Laboratory of Integrated Management of Pest Insects and Rodents in Agriculture, institute of Zoology, chinese academy of Sciences, beijing 100101, china 2 Kunming institute of Zoology, chinese academy of Sciences, Yunnan, 650223, china 3 The research institute of forest Ecology, Environment and Protection, The chinese academy of forestry, beijing 100091, china State Key Laboratory of Integrated Management of Pest Insects and Rodents in Agriculture Institute of Zoology Chinese Academy of Sciences Beijing China Kunming institute of Zoology Chinese Academy of Sciences Yunnan China The research institute of forest Ecology Environment and Protection The Chinese Academy of Forestry Beijing China

The Global Invasive Species Database, GISD, comprises 27 species of the most significant invasive alien insects in the world (through November, 2005), 6 of which are originally native to china, 11 are established in china, and 10 have a potential invasion threat to china. This paper discusses these species in terms of distribution, harmfulness and dispersal ways, and finds that: (i) information re-garding invasive insects in the GISD remains inadequate. Such harmful invasive species as Opogona sacchari (Bojer), Oracella acuta (Lobdell), and Dendroctonus valens LeConte are not included. (ii) Ten species of invasive insects, particularly Lasius neglectus Van Loon and Linepithema humile (Mayr) which become established in areas near china, have the potential to become established in china. (iii) Special attention should be paid to species from Asia and the Americas because of their greater likeli-hood of becoming established in china. Finally, some management strategies including legislation, quarantine, early warning, prevention and control are suggested.

关键词： biological invasions invasive species insect china

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Seasonal patterns of spatial differentiation of landcover change in china

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chinese Science Bulletin 1999年第4期44卷 362-364页

作者： CHEN YufengState Key Laboratory of resource and Environment information System , institute of Geography, chinese academy of Sciences, beijing 100101, china State Key Laboratory of resource and Environment information System Institute of Geography Chinese Academy of Sciences Beijing China

Using the 1°×1° NOAA AVHRR NDVI data set in china, an index on the spatial different gradient of landcover is created. Then based on the index and supported by the geographical information system, it is revealed through principal component and factor analyses methods that there exist four types of seasonal patterns of spatial differentiation of landcover change in china, i.e. November to next March type, June to September type, May or October type and April type.

关键词： landcover spatial differentiation seasonal pattern.

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A mixed finite element method for the unilateral contact problem in elasticity

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Science china Mathematics 2006年第4期49卷 513-524页

作者： HUA Dongying & WANG Lieheng The First Fundamental Department, beijing information technology institute, beijing 100101, china institute of Computational Mathematics and Scientific/Engineering Computing, academy of Mathematics and System Sciences, chinese academy of Sciences, beijing 100080, china The First Fundamental Department Beijing Information Technology Institute Beijing China institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing China

In this paper, we provide a new mixed finite element approximation of the variational inequality resulting from the unilateral contact problem in elasticity. We use the continuous piecewise P2-P1 finite element to approximate the displacement field and the normal stress component on the contact region. Optimal convergence rates are obtained under the reasonable regularity hypotheses. Numerical example verifies our results.

关键词： unilateral contact problem, mixed finite element method.

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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 China Graduate University of the chinese academy of Sciences Beijing China institute of forest resource information Technique the Chinese Academy of Forestry Beijing 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 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

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Fiducial intervals of restricted parameters and their applications

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Science china Mathematics 2005年第11期48卷 1567-1583页

作者： LI Xinmin, LI Guoying & XU Xingzhong College of Mathematics and information Sciences, Shandong University of technology, Zibo 255049, china academy of Mathematics and System Sciences, chinese academy of Sciences, beijing 100800, china Department of Mathematics, beijing institute of technology, beijing 100801, china College of Mathematics and information Sciences Shandong University of Technology Zibo China academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing China Department of Mathematics Beijing Institute of Technology Beijing China

In practice, the unknown parameters are often restricted. This paper provides a general method for constructing the fiducial intervals of the restricted parameters. Applying the general method, the fiducial intervals are constructed for the location (scale)parameters and the difference (ratio) of two locations (scales) in a location (scale) family of distributions. The frequency properties of these intervals are verified. For a variance components model, the fiducial intervals for the three parameters of common interest are obtained. Their frequency properties are investigated theoretically and computationally.

关键词： restricted parameter space,fiducial interval,frequency property,variance components

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Mechanism and Defense on Malicious Code

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Wuhan University Journal of Natural Sciences 2005年第1期10卷 83-88页

作者： WEN Wei-ping 1,2,3, QING Si-han 1,2,31. institute of Software, the chinese academy of Sciences, beijing 100080, china 2.Engineering research Center for information Security technology, the chinese academy of Sciences, beijing 100080, china 3.Graduate School of the chinese academy of Sciences, beijing 100080, china institute of Software the Chinese Academy of Sciences Beijing China Engineering research Center for information Security technology the Chinese Academy of Sciences Beijing China Graduate School of the chinese academy of Sciences Beijing China

With the explosive growth of network applications, the threat of the malicious code against network security becomes increasingly serious. In this paper we explore the mechanism of the malicious code by giving an attack model of the malicious code, and discuss the critical techniques of implementation and prevention against the malicious code. The remaining problems and emerging trends in this area are also addressed in the paper.

关键词： malicious code attacking model mechanism defense system security network security

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Revision of seismic design codes corresponding to building damagesin the “5.12” Wenchuan earthquake

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Earthquake Engineering and Engineering Vibration 2010年第2期9卷 147-155页

作者： Wang Yayong institute of Earthquake Engineering, china academy of Building research, beijing 100013, china institute of Earthquake Engineering China Academy of Building Research Beijing China

A large number of buildings were seriously damaged or collapsed in the "5.12" Wenchuan earthquake. Based on field surveys and studies of damage to different types of buildings, seismic design codes have been updated. This paper briefly summarizes some of the major revisions that have been incorporated into the "Standard for classification of seismic protection of building constructions GB50223-2008" and "Code for Seismic Design of Buildings GB50011-2001." The definition of seismic fortification class for buildings has been revisited, and as a result, the seismic classifications for schools, hospitals and other buildings that hold large populations such as evacuation shelters and information centers have been upgraded in the GB50223-2008 Code. The main aspects of the revised GB50011-2001 code include: (a) modification of the seismic intensity specified for the Provinces of Sichuan, Shanxi and Gansu; (b) basic conceptual design for retaining walls and building foundations in mountainous areas; (c) regularity of building configuration; (d) integration of masonry structures and precast RC floors; (e) requirements for calculating and detailing stair shafts; and (f) limiting the use of single-bay RC frame structures. Some significant examples of damage in the epicenter areas are provided as a reference in the discussion on the consequences of collapse, the importance of duplicate structural systems, and the integration of RC and masonry structures.

关键词： Wenchuan earthquake earthquake damage to buildings revision of seismic design codes

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