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Analysis of forest backscattering characteristics based on polarization coherence tomography

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,{3. 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 {3.,beijing 100101,china 3.nstitute of Forest Resources information Technique of Chinese Academy of Forestry,beijing 100091,china 4 School of Electronic Engineering,{3. of Electronic science and technology of china,Chengdu 610054,china State Key Lab Remote Sensing Sci Beijing 100101 Peoples R China beijing normal Univ Beijing 100101 Peoples R China Univ Elect Sci & Technol china Inst Geospatial Informat Sci & Technol Chengdu 610054 Peoples R China Chinese Acad Forestry Inst Forest Resources Informat Tech Beijing 100091 Peoples R China Univ Elect Sci & Technol china Sch Elect Engn Chengdu 610054 Peoples R 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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Synchronization of Digital Chaos in Secure Communication Systems

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Journal of university of science and technology {3. 2001年第4期8卷 299-305页

作者： Geng Zhao, Deling Zheng, ShaojunHuang 1)college of Electric science and technology {3.. {3. 100070, china 2)information Engineering School, university of science and technology {3.. {3. 100083. china Coll Elect Sci & Technol beijing Beijing 100070 Peoples R China Univ Sci & Technol beijing Informat Engn Sch Beijing 100083 Peoples R China

The theories of synchronization based on secure communications using digital chaos are presented. A new synchronous method-cycles-interval Pulse drive is developed and realized. Experimental results show it is available, and in order to reduce synchronous noise, a method using model references solves the ratio of signal power to noise power, so the secure communication system can be realized.

关键词： digital chaotic synchronization cycles-interval pulses drive synchronous noise model reference

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Retrieving crop leaf area index by assimilation of MODIS data into a crop growth model

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science china Earth sciences 2010年第5期53卷 721-730页

作者： WANG DongWei1,2,3. WANG JinDi1,2 & LIANG ShunLin4 1 State Key Laboratory of Remote Sensing science, Jointly Sponsored by beijing normal {3. and Institute of Remote Sensing Applications, CAS, beijing 100875, china 2 School of Geography, beijing Key Laboratory of Environmental Remote Sensing and Digital City, beijing normal {3., beijing 100875, china 3.Haihe River Water Conservancy Commission, Tianjin 3.0170, china 4 Department of Geography, {3. of Maryland, college Park, MD 20742, USA 1. State Key Laboratory of Remote Sensing science Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing Applications CAS Beijing 100875 China2. School of Geography Beijing Key Laboratory of Environmental Remote Sensing and Digital City Beijing Normal University Beijing 100875 China3. Haihe River Water Conservancy Commission Tianjin 300170 China4. Department of Geography University of Maryland College Park MD 20742 USA

Leaf area index (LAI) is an important parameter in monitoring crop growth. One of the methods for retrieving LAI from remotely sensed observations is through inversion of canopy reflectance models. Many model inversion methods fail to account for variable LAI values at different crop growth stages. In this research, we use the crop growth model to describe the LAI changes with crop growth, and consider a priori LAI values at different crop growth stages as constraint information. The key approach of this research is to assimilate multiple canopy reflectance values observed at different growth stages and a priori LAI values into a coupled crop growth and radiative transfer model sequentially using a variational data assimilation algorithm. Adjoint method is used to minimize the cost function. Any other information source can be easily incorporated into the inversion cost function. The validation results show that the time series of MODIS canopy reflectance can greatly reduce the uncertainty of the inverted LAI values. Compared with MODIS LAI product at Changping and Shunyi Counties of beijing, this method has significantly improved the estimated LAI temporal profile.

关键词： inversion leaf area index crop growth model time series MODIS

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Quasi-secure quantum dialogue using single photons

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science china(Physics,Mechanics & Astronomy) 2007年第5期50卷 558-562页

作者： YANG YuGuang1,2 & WEN QiaoYan3. college of Computer science and technology, {3. university of technology, {3. 100022, china 2 State Key Laboratory of information Security, Graduate university of the Chinese Academy of sciences, {3. 100049, china 3.School of science, {3. university of Posts and Telecommunications, {3. 100876, china college of Computer science technology Beijing University of Technology Beijing 100022 China State Key Laboratory of information Security Graduate University of the Chinese Academy of Sciences Beijing 100049 China School of science Beijing University of Posts Telecommunications Beijing 100876 China

A quasi-secure quantum dialogue protocol using single photons was proposed. Different from the previous entanglement-based protocols, the present protocol uses batches of single photons which run back and forth between the two parties. A round run for each photon makes the two parties each obtain a classical bit of information. So the efficiency of information transmission can be increased. The present scheme is practical and well within the present-day technology.

关键词： quantum dialogue, single photon, quantum secure direct communication

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Electronic structure and magnetism of Fe-doped SiC nanotubes

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science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1582-1589页

作者： ZHANG WeiHu1,2,3.ZHANG FuChun3.ZHANG ZhiYong4,LU ShuYuan5 & YANG YanNing3.1 Xi’an Institute of Optics and Precision Mechanics,Chinese Academy of sciences,Xi’an 710068,china 2 Graduate university of Chinese Academy of sciences,beijing 100049,china 3.college of Physics and Electronic information,Yan’an university,Yan’an 716000,china 4 information science and technology Institution,Northwest university,Xi’an 710127,china 5 Department of Telecommunications,Xi’an Institute of Posts and Telecommunications,Xi’an 710121,china 1. Xi’an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi’an 710068 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. College of Physics and Electronic Information Yan’an University Yan’an 716000 China4. Information Science and Technology Institution Northwest University Xi’an 710127 China5. Department of Telecommunications Xi’an Institute of Posts and Telecommunications Xi’an 710121 China

The electronic structure and magnetic properties of Fe-doped SiC nanotubes are investigated by using the first-principles method based on density functional theory(DFT) in the local spin density approximation(LSDA).The calculation results indicate that the SiC nanotube of Fe substitution for C exhibits antiferromagnetism while ferromagnetism features prominently when Fe substitutes *** is a kind of half-metal magnetic *** formation energy calculation results show that the formation energy of ferromagnetic structure is 3.2 eV lower than that of antiferromagnetic *** atoms are more likely to replace Si ***-orbit coupling induces electron spin polarization in the ground ***,the doping Fe atoms make relaxation towards the outside of the tube to some extent and larger geometric distortion occurs when Fe substitutes C,but the whole geometric structure of SiC nanotubes is not damaged due to the *** is revealed in the calculation of energy band structure and density of states that more dispersed distribution of energy levels is produced near the Fermi *** Fe substitution for Si,obviously there are spin-split and intense p-d hybrid effects by Si 3. electron spins and Fe 3. electron spins localized at the exchanging interactions between magnetic transitional metal(TM) *** electronic density results indicate that system magnetic moments are mainly generated by the unpaired 3. electrons of Fe *** these results show that the transition metal doping SiC nanotube could be a potential route to fabricating the promising magnetic materials.

关键词： SiC nanotube the first-principles doped magnetic properties

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Research progress in studies on the coalbed gas geochemistry

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Progress in Natural science:Materials International 2006年第3期16卷 215-220页

作者： TAO Mingxin (college of Resources sciences & technology, {3. normal university, beijing 100875, china Key Laboratory of Gas Geochemistry, Institute of Geology and Geophysics, Chinese Academy of sciences, Lanzhou 73.000, china) [a]college of Resources sciences & technology Beijing Normal University Beijing China [b]Key Laboratory of Gas Geochemistry Institute of Geology and Geophysics Lanzhou China

The current situation of geochemical studies on coalbed gas is reviewed in this paper. Generally, coalbed gas is composi-tionally dominated by methane with δ13.1 values ranging approximately from - 80‰ to - 10‰. However, few isotopic studies have been carried out on other components of coalbed gas except for hydrogen and carbon dioxide, whose δDCH4 values available for utilization vary from - 3.3. to - 117‰, and δ13.CO2 values from - 29. 4‰ to + 18. 6‰. Two major types of coalbed gas, thermogenic gas and secondary biogenic gas, have been identified, and there are also some other classification criteria. Compared with conventional natural gases, coalbed gas has a wide distribution range of δ13.1 and δ13.CO2 values, especially possessing some extremely heavy values. Current problems that remain unsolved in the coalbed gas geochemistry include the variation mechanism, controlling factors and application of carbon and hydrogen isotopes of methane, the relation between the values of δ13.1 and Ro, the systematic classification scheme and criterion of genetic types, and the application of the coalbed gas geochemistry in evaluating target districts of the coalbed gas exploration.

关键词： coalbed gas geochemistry isotopic composition genetic type novel resource.

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Influence of Zn ion implantation on structures and field emission properties of multi-walled carbon nanotube arrays

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science china(Technological sciences) 2010年第3期53卷 776-781页

作者： CHEN KeFan,DENG JianHua,ZHAO Fei,CHENG GuoAn &ZHENG RuiTing Key Laboratory of Beam technology and Material Modification of Ministry of Education,college of Nuclear science and technology,beijing normal university,beijing100875,china 1. Key Laboratory of Beam technology and Material Modification of Ministry of Education College of Nuclear Science and Technology Beijing Normal University Beijing 100875 China

The structures and field emission properties of multi-walled carbon nanotube arrays implanted with Zn+ by MEVVA ion implanter have been *** results revealed that Zn+implantation induced structural damage and that the top of carbon nanotubes with multi-layered graphite structure were transformed into carbon nanowires with amorphous ***,C:Zn solid solution was synthesized after Zn+ *** turn-on field and threshold field were 0.80 and 1.3. V/μm,respectively for original multi-walled carbon nanotube arrays and were reduced to 0.66 and 1.04 V/μm due to the synthesis of C and Zn composite,in which the work function was reduced after low doses of Zn+*** is indicated that low doses of Zn+implantation can improve field emission performance of multi-walled carbon nanotube ***,high doses of Zn+implantation can reduce field emission properties of multi-walled carbon nanotube arrays,because radiation damage reduces the electric field enhancement factor.

关键词： multi-walled carbon nanotubes ion implantation field electron emission

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Suitability evaluation for land reclamation in mining area:A case study of Gaoqiao bauxite mine

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中国有色金属学会会刊：英文版 2011年第S3期21卷 506-515页

作者： WANG Shi-dong1, 2, LIU Chang-hua2, ZHANG He-bing2 1. college of Resources science and technology, {3. normal university, beijing 100875, china 2. School of Surveying and Land information Engineering, Henan Polytechnic university, Jiaozuo 454000, china [a] college of Resources science and technology Beijing Normal University Beijing 100875 China [b] School of Surveying and Land information Engineering Henan Polytechnic University Jiaozuo 454000 China

Suitability evaluation plays an important role in land reclamation because the choice of evaluation methods affects the accuracy and objectivity of the suitability evaluation results. Furthermore, it influences the decision-making related to land reclamation. An improved method, which is called limit comprehensive conditions method, was developed after different suitability evaluation methods were studied. Based on this method, the reclaimed land of the Gaoqiao bauxite mining area was evaluated. The Gaoqiao mining area was divided into seven evaluation units that were evaluated respectively by selecting evaluation factors and establishing grade standards. The results show that the proposed method is more applicable and easier to handle. Moreover, its evaluation results are more scientific compared with the traditional evaluation methods. The improved method can be beneficial to the rapid monitoring and the effective management of reclaimed land in the opencast mine area.

关键词： mining area land reclamation suitability evaluation Gaoqiao bauxite mine

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Shell effect and capture cross sections in the synthesis of superheavy nuclei

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science china(Physics,Mechanics & Astronomy) 2009年第10期52卷 1489-1493页

作者： DU SaiSai1,2,BIAN BaoAn1,2,3.LIU Min1,2,4,FENG ZhaoQing5,6 & ZHANG FengShou1,2,6 1 Key Laboratory of Beam technology and Material Modification of Ministry of Education,college of Nuclear science and technology,beijing normal university,beijing 100875,china 2 beijing Radiation Center,beijing 100875,china 3.School of science,Jiangnan university,Wuxi 214122,china 4 college of Physics and technology,Guangxi normal university,Guilin 541004,china 5 Institute of Modern Physics,Chinese Academy of sciences,Lanzhou 73.000,china 6 Center of Theoretical Nuclear Physics,National Laboratory of Heavy Ion Accelerator of Lanzhou,Lanzhou 73.000,china Key Laboratory of Beam technology and Material Modification of Ministry of Education College of Nuclear Science and Technology Beijing Normal University Beijing 100875 China beijing Radiation Center Beijing 100875 China School of science Jiangnan University Wuxi 214122 China college of Physics and technology Guangxi Normal University Guilin 541004 China Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou 730000 China

The shell effect is included in the improved isospin dependent quantum molecular dynamics model in which the shell correction energy of the system is calculated by using the deformed two-center shell model. A switch function is introduced to connect the shell correction energy of the projectile and the target with that of the compound nucleus during the dynamical fusion process. It is found that the calculated capture cross sections reproduce the experimental data quantitatively at the energy near the Coulomb barrier. The capture cross sections for reaction 3. 80 Br + 82 208 Pb → 117 288 X are also calculated and discussed.

关键词： superheavy nuclei transport theory shell effect cross sections

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From the Green's Function in Tight-Binding Representation to Interatomic Many-body Potentials

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Journal of Materials science & technology 1999年第4期15卷 315-319页

作者： Shaojun LIU(Department of physics, beijing normal university,{3., china)Xiaobo WEI(Department of Physics, Liuzhou college of Education, Liuzhou 545005, china)Zhaodou CHEN Jun CAI and Benkun MA(Department of Physics, beijing normal university, beijing normal Univ Dept Phys Beijing 100875 Peoples R China Liuzhou Coll Educ Dept Phys Liuzhou 545005 Peoples R China

In this paper, we deduce the analytical form of many-body interatomic potentials based on the Green's function in tight-binding representation. The many-body potentials are expressed as the functions of the hopping integrals which are the physical origin of cohesion of atoms. For thesimple case of s-valent system, the inversion of the many-body potentials are discussed in detail by using the lattice inversion method.

关键词： Rev Li Chen From the Green’s Function in Tight-Binding Representation to Interatomic Many-body Potentials body

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