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Polynomial analysis of canopy spectra and biochemical component content inversion

Science china Earth Sciences 2005年第10期48卷 1780-1791页

作者： YAN Chunyan1, LIU Qiang1, NIU Zheng1, WANG Jihua2, HUANG Wenjiang2 & LIU Liangyun 2 1. 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 2. National Engineering research Center for Information technology in Agriculture, beijing 100089, 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 National Engineering research Center for Information technology in Agriculture beijing china

A polynomial expression model was developed in this paper to describe directional canopy spectra, and the decomposition of the polynomial expression was used as a tool for re-trieving biochemical component content from canopy multi-angle spectra. First, the basic formula of the polynomial expression was introduced and the physical meaning of its terms and coeffi-cients was discussed. Based on this analysis, a complete polynomial expression model and its decomposition method were given. By decomposing the canopy spectra simulated with SAILH model, it shows that the polynomial expression can not only fit well the canopy spectra, but also show the contribution of every order scattering to the whole reflectance. Taking the first scattering coefficients a10 and a01 for example, the test results show that the polynomial coefficients reflect very well the hot spot phenomenon and the effects of viewing angles, LAI and leaf inclination angle on canopy spectra. By coupling the polynomial expression with leaf model PROSPECT, a canopy biochemical component content inversion model was given. In the simulated test, the canopy multi-angle spectra were simulated by two different models, SAILH and 4-SCALE re-spectively, then the biochemical component content was retrieved by inverting the coupled polynomial expression + PROSPECT model. Results of the simulated test are promising, and when applying the algorithm to measured corn canopy multi-angle spectra, we also get relatively accurate chlorophyll content. It shows that the polynomial analysis provides a new method to get biochemical component content independent of any specific canopy model.

关键词： polynomial expression, canopy spectra, decomposition, biochemical component content, inversion.

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Hydraulic characteristics of converse curvature section and aerator in high-head and large discharge spillway tunnel

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Science china(Technological Sciences) 2011年第S1期54卷 33-39页

作者： LIU ZhiPing 1,2,ZHANG Dong 2,ZHANG HongWei 2 &WU YiHong 1,2 1 State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin,beijing 100038,china 2 china institute of Water Resources and Hydropower research,beijing 100038,china 1. State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin Beijing 100038 China2. China Institute of Water Resources and Hydropower Research Beijing 100038 China

The hydraulic characteristics and cavitation erosion near the converse curvature section in the high-head and large discharge spillway tunnel have been important issues of concern to the hydropower *** this paper,the evolutions of hydraulic elements such as pressure,flow velocity,wall shear stress,*** the converse curvature section are analyzed and the impacts of bottom aerator on hydraulic characteristics are discussed,with the commercial software FLUENT6.3 as a platform and combining the k-model and VOF *** flow pattern in the converse curvature section of spillway tunnel is given by the three-dimensional numerical *** indicates that the pressure changes rapidly with great pressure gradient from the beginning to the end of the *** also shows that the shear stress on side wall just downstream the end of the converse curvature curve is still increasing;the aeration cavity formed downstream the bottom aerator may cause the side wall pressure decreased to worsen the cavitation characteristics near the side *** means of the physical model experiment,the three-dimensional aerator composed of side wall baffling aerator and bottom aerator is studied,the baffling aerator suitable for the water flow conditions with water depth of 6.0 to 8.0 m and flow velocity of 35 to 50 m/s is proposed.

关键词： spillway tunnel baffling aerator converse curvature section hydraulic characteristics

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2.5-dimensional angle potential field algorithm for the real-time autonomous navigation of outdoor mobile robots

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Science china(Information Sciences) 2011年第10期54卷 2100-2112页

作者： QIU Quan 1,3 & HAN JianDa 2 1 beijing research Center of Intelligent Equipment for Agriculture,beijing 100097,china 2 State Key Laboratory of Robotics,Shenyang institute of Automation,Chinese Academy of Sciences,Shenyang 110016,china 3 National research Center for Intelligent Agricultural Equipment,beijing 100097,china 1. beijing research Center of Intelligent Equipment for Agriculture Beijing 100097 China3. National Research Center for Intelligent Agricultural Equipment Beijing 100097 China2. State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences Shenyang 110016 China

A new real-time algorithm for the autonomous navigation of mobile robots equipped with laser scanners is proposed in this *** from the existing algorithms designed for 2-dimensional navigation problems,the new algorithm introduces the height information of the obstacles into the guidance process and behaves as a 2.5-dimensional angle potential field algorithm (2.5D-APF) to fulfill the navigation requirements under complex outdoor terrain ***,one laser scan is partitioned into two kinds of function sectors: guidance sector and inspecting ***,the guidance sector and the inspecting sectors are reconstructed to form a virtual guidance scan,where the 2.5D information is taken into ***,the conventional APF is improved to analyze the virtual guidance scan and generate the navigation *** new algorithm is tested on a tracked mobile robot,and the experimental results validate the proposed algorithm.

关键词： robot 2.5-dimensional outdoor real-time autonomous navigation

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The discrete multiple-parameter fractional Fourier transform

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Science china(Information Sciences) 2010年第11期53卷 2287-2299页

作者： LANG Jun, TAO Ran& WANG Yue Department of Electronic Engineering, beijing institute of technology, beijing 100081, china 1. Department of Electronic Engineering Beijing Institute of Technology Beijing 100081 China

As a generalization of the Fourier transform (FT), the fractional Fourier transform (FRFT) has many applications in the areas of optics, signal processing, information security, etc. Therefore, the efficient discrete computational method is the vital fundament for the application of the fractional Fourier transform. The multiple-parameter fractional Fourier transform (MPFRFT) is a generalized fractional Fourier transform, which not only includes FRFT as special cases, but also provides a unified framework for the study of FRFT. In this paper, we present in detail the discretization method of the MPFRFT and define the discrete multiple-parameter fractional Fourier transform (DMPFRFT). Then, we utilize the tensor product to define two-dimensional multiple-parameter fractional Fourier transform (2D-MPFRFT) and the corresponding two-dimensional discrete multiple-parameter fractional Fourier transform (2D-DMPFRFT). Finally, as an application, a novel image encryption method based on 2D-DMPFRFT is proposed. Numerical simulations are performed to demonstrate that the proposed method is reliable and more robust to blind decryption than several existing methods.

关键词： multiple-parameter fractional Fourier transform fractional Fourier transform image encryption information security

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The correlation of multi-angle thermal infrared data and the choice of optimal view angles

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Science china Earth Sciences 2004年第6期47卷 570-576页

作者： FAN Wenjie1 & XU Xiru1,2 1.institute of Remote Sensing and GIS of Peking University,beijing 100871,china 2.Center of Remote Sensing and GIS of beijing Normal University,beijing 100875,china 1. institute of Remote Sensing and GIS of Peking University 100871 Beijing China 2. Center of Remote Sensing and GIS of beijing Normal University 100875 Beijing China

Based on the matrix formula of thermal infrared radiant system, the components temperature can be retrieved by the inversive matrix. Around the stability problem of retrieved result, the research work we did was focused on (i) the correlation of (wk,j) which is the key to affect the retrieval accuracy, (ii) a general method which can help us find the number of retrievable parameters and evaluate the retrieval error before its performance, (iii) the choice of “optimal viewing angle group” based on the formula of absolute error propagation. The row winter wheat field was chosen as an example. The results can provide a theoretical basis for multi-angle thermal infrared remote sensing and components temperature retrieval.

关键词： components temperature retrieval, correlation, number of retrievable parameters, optimal viewing angle group.

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Integral ear elimination and virtual point-based updating algorithms for constrained Delaunay TIN

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Science china(Technological Sciences) 2008年第S1期51卷 135-144页

作者： WU LiXin1,2,WANG YanBing2,3 & SHI WenZhong2,4 1 institute for Geo-informatics & Digital Mine research,Northeastern University,Shenyang 110004,china 2 institute for GIS/RS/GPS & Subsidence Engineering research,china University of Mining & technology,beijing 100085,china 3 Laboratory of 3D Information Acquisition & Application,Capital Normal University,beijing 100037,china 4 Center for Advanced GIS research,LSGI,Polytechnic University Hong Kong,Hong Kong,china Northeastern Univ Inst Geoinformat & Digital Mine Res Shenyang 110004 Peoples R China china Univ Mining & Technol Inst GIS RS GPS & Subsidence Engn Res Beijing 100085 Peoples R China Capital Normal Univ Lab Informat Acquisit & Applicat Beijing 100037 Peoples R China Hong Kong Polytech Univ LSGI Ctr Adv GIS Res Hong Kong Hong Kong Peoples R China

Constrained Delaunay Triangular Irregular Networks (CD-TIN),a kind of special data structure,have many practical applications in Geoinformatics,especially in the representation of linear constrained triangulation for DTM and DSM,such as in digital city and digital mine. Past researches on D-TIN mainly focused on point in-sertion and deletion without consideration of constraint,and that on CD-TIN usu-ally paid more attention to the insertion algorithms for points and edges,but little to the deletion algorithms. The presented algorithms are far insufficient for the dy-namic updating of CD-TIN. In this paper,the constraint edge in CD-TIN is consid-ered to be any set of broken lines,i.e.,polygon edges,broken lines and simple segments. The constraint edge may be composed of one or more constraint seg-ments,and it is allowed to be in any form: Open or close,intersection or self-in-tersection. By improving to present insertion and deletion algorithms for D-TIN,two new algorithms for CD-TIN updating are presented. According to the polymorphism of the constraints in CD-TIN,virtual point is adopted to represent the crossing node between constraint edges when a constraint edge is inserted in CD-TIN. Two new algorithms named as Integral Ear Elimination (IEE) and Influence Domain Retrian-gulation for Virtual Point (IDRVP) are presented,the former is for constraint point deletion,while the later is for the insertion and deletion of constraint edge. The principle of IDRVP is that to divide the influence domain of a virtual point into some parts by the constraint-keeping edges,and to retriangulate each part of the influ-ence domain individually referring to the constraint visible property and constraint empty circle (CEC) criterion. Finally,a prototype system is developed with VC++,one case on the integration of 3D terrain and buildings is demonstrated to test the correctness of new algorithms. It shows that the new algorithms are effective for the updating of CD-TIN.

关键词： Delaunay TIN spatial constraint data updating spatial modeling polymorphism digital mine

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Semi-solid Casting of High Speed Steel Ingots Using Inclined Slope Pre-crystallization Method

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Journal of Wuhan University of technology(Materials Science) 2009年第5期24卷 750-752页

作者：和优锋 State Key Laboratory for Fabrication and Process of Nonferrous Metals General Research Institute for Nonferrous Metals

Semi-solid casting of M2 high speed steel ingots was investigated by inclined slope pre-crystallization method. Effects of casting temperature and slope length on the microstructure of M2 HSS ingots were investigated. M2 cast ingots of non-dendritic primary austenite and fine eutectic ledeburite network carbide structure were obtained, with the casting temperature, slope length and angle of 1480 ℃, 500 mm and 60° respectively. Meanwhile, the microstructure of cast samples was quantitatively assessed by Image tool software. Results show that optimum mean equivalent diameter of primary austenite crystal grain is 50.8 μm, shape factor is 0.83, and mean thickness of network carbide is 5.21 μm.

关键词： M2 high speed steel semi-solid pre-crystallization inclined slope

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DNA Damage, Signaling and Repair: Protecting genomic integrity and reducing the risk of human disease

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Chinese Science Bulletin 2011年第30期56卷 3119-3121页

作者： ZHOU PingKun Department of Radiation Toxicology and Oncology, beijing institute of Radiation Medicine, beijing 100850, china special Topic Editor Department of Radiation Toxicology and Oncology Beijing Institute of Radiation Medicine

DNA is the genetic material that contains the 'instructions' to not only guide the continuation of life but also govern the development, metabolism and functioning of living organisms. DNA damage occurs daily due to v... 详细信息

关键词： DNA损伤基因组伤信号人类疾病整性修复风险保护

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Analysis of moment invariants under general linear transformation

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Science china(Information Sciences) 2010年第7期53卷 1305-1311页

作者： DIAO LuHong1, LI Hua2, ZHANG Sen1 & LIU Lei1 1College of Applied Sciences, beijing University of technology, beijing 100124, china 2National Center of Intelligent Computing, institute of Computing technology, Chinese Academy of Science, beijing 100080, china 1. College of Applied Sciences Beijing University of Technology Beijing 100124 China2. National Center of Intelligent Computing Institute of Computing Technology Chinese Academy of Science Beijing 100080 China

This paper presents the necessary and sufficient condition of moment invariants under general linear transformation. Based on this condition, arbitrary order and dimensional moment invariant sets can be constructed. D... 详细信息

关键词： moment invariants independence linear transformation

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Integrative inversion of land surface component temperature

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Science china Earth Sciences 2005年第11期48卷 2011-2019页

作者： FAN Wenjie1 & XU Xiru1,2 1. institute of Remote Sensing and Geographical Information System, Peking University, beijing 100871, china 2. Center of Remote Sensing and GIS of beijing Normal University, beijing 100875, china 1. institute of Remote Sensing and Geographical Information System Peking University 100871 Beijing China 2. Center of Remote Sensing and GIS of beijing Normal University 100875 Beijing China

In this paper, the row winter wheat was selected as the example to study the com-ponent temperature inversion method of land surface target in detail. The result showed that the structural pattern of row crop can affect the inversion precision of component temperature evi-dently. Choosing appropriate structural pattern of row crop can improve the inversion precision significantly. The iterative method combining inverse matrix was a stable method that was fit for inversing component temperature of land surface target. The result of simulation and field ex-periment showed that the integrative method could remarkably improve the inversion accuracy of the lighted soil surface temperature and the top layer canopy temperature, and enhance inver-sion stability of components temperature. Just two parameters were sufficient for accurate at-mospheric correction of multi-angle and multi-spectral thermal infrared data: atmospheric trans-mittance and the atmospheric upwelling radiance. If the atmospheric parameters and component temperature can be inversed synchronously, the really and truly accurate atmospheric correction can be achieved. The validation using ATSRII data showed that the method was useful.

关键词： components temperature, inverse pattern, atmospheric correction

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