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Monitoring of rice crop using ENVISAT ASAR data

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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 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 Forestry Beijing 100091 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.

Effect of Carbon on Dynamic Recrystallization Behavior of Vanadium Microalloy Steels

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Journal of Iron and Steel Research International 2011年第S1期18卷 129-134页

作者： LIU Guo-quan 1,2,ZHAO Hai-tao 1,WU Jin-bin 1,WANG Cheng-yang 1,XU Lei 1,3 (1.School of Materials Science and Engineering,University of Science and Technology beijing,beijing 100083,china 2.state key laboratory for Advanced Metals and Materials,University of Science and Technology beijing,beijing 100083,china 3.Department of Materials Science and Engineering,Tsinghua University,beijing 100084,china) Univ Sci & Technol beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China Univ Sci & Technol beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China Tsinghua Univ Dept Mat Sci & Engn Beijing 100084 Peoples R China

The hot working behavior especially dynamic recrystallization of low-carbon and medium-carbon vanadium microalloy steels has been studied by performing isothermally compression tests and Avrami *** Avrami plots of the two experiment steels have been constructed based on flow stress curves following a new approach (Jonas,et *** Mater.,2009,57(2):2748-2756;Wu et al,Acta ***.,2010,46(7):838-843).It is experimentally found that the carbon effect on dynamic recrystallization is opposite to each other in lower and higher strain ranges:Carbon causes a softening effect at low strain rates (0.01,0.1,and 1.0 s-1),and a hardening effect at high strain rates (10.0 and 30.0 s-1).Correspondingly,carbon promotes the dynamic recrystallization at low strain rates and retards the dynamic recrystallization at high strain rates in the experimental *** phenomenon is then tentatively explained based on the possible mechanisms of dynamic process at different strain rates.

关键词： vanadium microalloy steels hot working dynamic recrystallization carbon strain rate Avrami modeling

Convergence for Imaginary Time Step evolution in the Fermi and Dirac seas

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Science china(Physics,Mechanics & Astronomy) 2010年第2期53卷 327-330页

作者： LI FangQiong1,ZHANG Ying2 & MENG Jie2,3,4 1Guizhou University for Nationalities,Guiyang 550025,china 2state key lab Nucl. Phys. & Tech.,School of Physics,Peking University,beijing 100871,china 3School of Physics and Nuclear Energy Engineering,Beihang University,beijing 100191,china 4Department of Physics,University of Stellenbosch,Stellenbosch,South Africa 1. Guizhou University for Nationalities Guiyang 550025 China2. State Key Lab Nucl. Phys. & Tech. School of Physics Peking University Beijing 100871 China3. School of Physics and Nuclear Energy Engineering Beihang University Beijing 100191 China4. Department of Physics University of Stellenbosch Stellenbosch South Africa

The convergence for the Imaginary Time Step (ITS) evolution with time step is investigated by performing the ITS evolution for the Schrdinger-like equation and the charge-conjugate Schrdinger-like equation deduced from Dirac equation for the single proton levels of 12C in both the Fermi and Dirac seas. For the guaranteed convergence of the ITS evolution to the "exact" results,the time step should be smaller than a "critical" time step Δtc for a given single-particle level. The "critical" time step Δtc is more sensitive to the quantum numbers |κ| than to the energy of the single-particle level. For the single-particle levels with the same κ,their "critical" time steps are in the same order. For the single-particle levels with similar energy,a relatively small (large) "critical" time step for larger (smaller) |κ| is needed. These conclusions can be used in the future self-consistent calculation to optimize the evolution procedure.

关键词： Dirac equation Schrdinger-like equation Imaginary Time Step method convergence

Wave coupling between the Tianshan orogen and the deformations in its south and north foreland basins in Cenozoic

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Science china Earth Sciences 2008年第S2期51卷 61-69页

作者： CHEN ShuPing1,2,TANG LiangJie & YU YiXin1,2 1 state key laboratory of Petroleum Resource and Prospecting,china University of Petroleum,beijing 102249,china 2 Department of Geoscience,china University of Petroleum,beijing 102249,china china Univ Petr State Key Lab Petr Resource & Prospecting Beijing 102249 Peoples R China china Univ Petr Dept Geosci Beijing 102249 Peoples R China

Attention has been paid to the deformations in the south and north foreland basins of the Tianshan Mountains and their relations to the tectonic movements of the mountains. Based on the seismic data interpretation and field work,the tectonic features,tectonic styles,controlling factors of deformation,deformation time,and their relationships in the three tectonic units were comparably studied. The Ce-nozoic deformations in the two foreland basins were characterized by zonation from south to north,segmentation from west to east,and layering from deep to shallow. The tectonic styles are compres-sive ones,including both basement-involved and cover-detaching. The two foreland basins underwent several times of deformation in Cenozoic and the deformations were transmitted from the Tianshan orogen to the inner basin. The deformation dynamics of the south and north foreland basins of the Tianshan Mountains can be represented by dynamics of orogenic wedges. In terms of the deformations of the wedges with wave-like features,the concept of a wave orogenic wedge was put forward,and a double wave orogenic wedge model was established.

关键词： Tianshan orogen basin-mountain coupling tectonics wave orogenic wedge

Modeling diameter distribution of the broadleaved-Korean pine mixed forest on Changbai Mountains of china

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Science china(Technological Sciences) 2006年第z1期49卷 177-188页

作者： WANG Shunzhong, DAI Limin, LIU Guohua, YUAN Jianqiong, ZHANG Hengmin & WANG Qingli Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, china Graduate University of Chinese Academy of Sciences, beijing 100039, china state key lab.of Systems Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, beijing 100085, china Institute of Applied Ecology Chinese Academy of Sciences Shenyang 110016 China Graduate University of Chinese Academy of Sciences Beijing 100039 China state key lab.of Systems Ecology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China

The broadleaved-Korean pine mixed forest is a native vegetation in the Changbai Mountains, northeast china. The probability density functions including the normal, negative exponential, Weibull and finite mixture distribution, were used to describe the diameter distributions of the species groups and entire forest stand. There is a strong correlation between parameters and mean DBH except the shape parameters in the mixture distribution. The diameter classes of species and entire forest stand showed not negative exponential but normal and "S" distribution. The mixture function was better than normal and Weibull to describe the model distribution. The location parameter had an effect on the estimated frequency in the first diameter class, when the estimated location parameter was bigger than the lower limit of the first diameter class.

关键词： broadleaved-Korean pine mixed forest, diameter distribution, finite mixture distribution.

biomimetic synthesis of calcium-strontium apatite hollow nanospheres

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Science china Chemistry 2010年第8期53卷 1723-1727页

作者： GAN Yong,HAN DongMei,GU FuBo,WANG ZhiHua & GUO GuangSheng state key laboratory of Chemical Resource Engineering,beijing University of Chemical Technology,beijing 100029,china 1. state key laboratory of Chemical Resource Engineering Beijing University of Chemical Technology Beijing 100029 China

In this work,calcium-strontium apatite (Sr-HA) hollow nanospheres were synthesized by a facile biomimetic *** structure and property of Sr-HA were characterized by FESEM,TEM,HRTEM,XRD and FT-IR *** influences of different ratios of calcium and strontium on the morphologies of the Sr-HA products were *** experimental results revealed that the hollow spherical Sr-HA,with a size of 30-120 nm in diameter,could be synthesized when the molar ratio of Ca/Sr was 1:*** possible formation mechanism of the hollow Sr-HA was *** drug release experiments indicated that the hollow spherical Sr-HA had the property of sustained release.

关键词： calcium-strontium apatite hollow nanosphere biomimetic synthesis

Luminescence resonance energy transfer based on β-NaYF_4:Yb,Er nanoparticles and TRITC dye

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Science china Chemistry 2009年第10期52卷 1590-1595页

作者： SUN LingDong, GU JianQin, ZHANG ShuZhuo, ZHANG YaWen & YAN ChunHua beijing National laboratory for Molecular Sciences, state key lab.of Rare Earth Materials Chemistry and Applications & PKU-HKU Joint lab in Rare Earth Materials and Bioinorganic Chemistry, College of Chemistry and Molecular Engineering, Peking University, beijing 100871, china 1. beijing National laboratory for Molecular Sciences State Key Lab of Rare Earth Materials Chemistry and Applications & PKU-HKU Joint Lab in Rare Earth Materials and Bioinorganic Chemistry College of Chemistry and Molecular Engineering Peking University Beijing 100871 China

β-NaYF4:Yb,Er nanoparticles (NPs) are one of the most efficient upconversion materials, which can convert near-infrared light to higher-energy light through multiple photon absorptions or energy transfer. In addition, they may be attractive alternative donors for luminescence resonance energy transfer (LRET) studies, because of their sharp absorption and emission profiles, high quantum yields, large anti-stokes shifts, long lifetime, low toxicity, and superior photo-stability. In principle, many problems of fluorescence resonance energy transfer (FRET), such as excitation of acceptors, emission overlaps between donors and acceptors, high background noise, potential toxicity, and instability, can be overcome using β-NaYF4:Yb,Er NPs as energy donors. Because the organic coating induced separation can significantly reduce the energy transfer efficiency and aqueous FRET system is difficult to be applied in devices, we demonstrate a novel NP-dye LRET system in solid state. The emission of the β-NaYF4:Yb,Er NPs at 539 nm overlaps with the absorption of the tetrametrylrhodarnine isothiocyante (TRITC), satisfying the requirement of LRET process. Since TRITC molecules are adsorbed on the β-NaYF4:Yb,Er NPs by an electrostatic interaction, the interaction distance is suitable for LRET without any further modulation. The resultant solid LRET system is ready for the further applications for devices.

关键词： upconversion emission β-NaYF4:Yb Er nanoparticles TRITC assembly luminescence resonance energy transfer (LRET)

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 Resources 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 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

Chemical Constituents from Fruits of Gymnocladus chinensis

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Chinese Herbal Medicines 2009年第1期1卷 66-70页

作者： HAN Li1,2, FU Hong-zheng1 1. state key laboratory of natural and biomimetic drugs, Peking University, beijing 100083, china 2. Department of natural Products Chemistry, Pharmaceutical Science School, china Medical University, Shenyang 110001, china state key laboratory of natural and biomimetic drugs Peking UniversityBeijing 100083China Department of natural Products Chemistry Pharmaceutical Science SchoolChina Medical UniversityShenyang 110001China state key laboratory of natural and biomimetic drugs Peking UniversityBeijing 100083China

Objective To study chemical constituents from fruits of Gymnocladus chinensis. Methods The compounds were isolated by various chromatographic techniques and their structures were elucidated on the basis of spectral analyses. Results Ten compounds were isolated from the EtOAc extract and were identified as 2-methyl pentyl (2E, 6S)-6-hydroxy-2, 6-dimethyl-2, 7-octadienoate (1), (2E, 6S)-6-α-L-arabino pyranosyloxy-2, 6-dimethyl-2, 7-octadienoic acid (2), ethyl (2E, 6S)-6-hydroxy-2, 6-dimethyl-2, 7-octadienoate (3), 5, 2’, 5’-trihydroxy-3, 7, 4’-trimethoxyflavone (4), (2R, 3R)-3, 3’, 5, 5’, 7-pentahydroxyflavanone (5), 2’, 4’-dihydroxy-4-methoxychalcone (6), kaempferol (7), apigenin (8), 4’, 7-dihydroxyflavone (9), and 5, 7, 4’-trihydroxy-3’-methoxyflavone (10). Conclusion Compound 1 is a new compound, compound 3 is firstly obtained from natural source, and compounds 4 -10 are isolated from G. chinensis for the first time. Furthermore, the assignments of 13C-NMR data of compounds 3 and 4 are reported in this paper for the first time.

关键词： chemical constituents flavone Gymnocladus chinensis Baill. monoterpene