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A cyclic behavior of CME accelerations for accelerating and decelerating events

Research in Astronomy and Astrophysics 2009年第10期9卷 1165-1172页

作者： Peng-Xin Gao Ke-Jun Li National Astronomical Observatories / Yunnan Observatory Chinese Academy of Sciences Kunming 650011 China graduate university of chinese academy of sciences Beijing 100049 China

We investigate the cyclic evolutionary behavior of CME accelerations for accelerating and decelerating CME events in cycle 23 from 1997 January to 2007 December. It is found that the absolute values of semiannual mean accelerations of both accelerating and decelerating CME events roughly wax and wane in a cycle, delaying the sunspot cycle in time phase. We also investigate the semiannual number of CMEs with positive and neg- ative acceleration and find that there are more decelerating CME events than accelerating CME events during the maximum period of a cycle （about three years）, but there are more accelerating CME events than decelerating CME events during the rest of the time interval of the cycle. Our results seem to suggest that the different driving mechanisms may be acting accelerate and decelerate CME events; for accelerating CME events, the propelling force （Fp） statistically seems to play a significant role in pushing CMEs outward; for decelerating CME events, the drag （Fd） statistically seems to play a more effective role in determining CME kinematic evolution in the outer corona. During the maximum period of a cycle, because of the V^2 dependence, Fd is generally stronger; because of the magnetic field dependence, Fp is also generally stronger. Thus, the absolute values of both the negative and positive accelerations are generally larger during that time. Because of the V^2 dependence, Fd may be more effective during the maximum period of a cycle. Hence, there are more decelerating CME events than accelerating CME events during that time. During the minimum time interval of a cycle, CMEs have relatively small speeds, and Fp may be more effective. Therefore, there are more accelerating CME events than decelerating CME events during that time.

关键词： Sun corona -- Sun coronal mass ejections (CMEs)

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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 3p electron spins and Fe 3d 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 3d 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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Three-dimensional decomposition method of global atmospheric circulation

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Science china Earth sciences 2008年第3期51卷 386-402页

作者： LIU HaiTao1,2,3, HU ShuJuan4, XU Ming5 & CHOU JiFan6,7 1 State Key Laboratory of Numerical Modeling for Atmospheric sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, chinese academy of sciences, beijing 100029, china 2 graduate university of chinese academy of sciences, beijing 100049, china 3 beijing Climate Center, beijing 100089, china 4 Department of Mathematics, Lanzhou university, Lanzhou 730000, china 5 Shanghai Typhoon Institute, Shanghai 200030, china 6 Department of Atmospheric sciences, Lanzhou university, Lanzhou 730000, china 7 china Meteorological Administration Training Center, beijing 100089, china 1. State Key Laboratory of Numerical Modeling for Atmospheric sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China 2. graduate university of chinese academy of sciences Beijing 100049 China 3. beijing Climate Center Beijing 100089 China 4. Department of Mathematics Lanzhou University Lanzhou 730000 China 5. Shanghai Typhoon Institute Shanghai 200030 China 6. Department of Atmospheric sciences Lanzhou University Lanzhou 730000 China 7. china Meteorological Administration Training Center Beijing 100089 China

By adopting the idea of three-dimensional Walker, Hadley and Rossby stream functions, the global atmospheric circulation can be considered as the sum of three stream functions from a global perspective. Therefore, a m... 详细信息

关键词： three-dimensional decomposition of the global atmospheric circulation generalized Walker Hadley and Rossby stream functions existence and uniqueness vertical motion

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Monitoring Dynamic Change of Land Cover Based on SVM and Satellite Images in Hanoi,Vietnam

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Wuhan university Journal of Natural sciences 2010年第4期15卷 355-362页

作者： ZHAO Jinling1,2, LIU Chuang1, 3 1. Institute of Geographic sciences and Natural Resources Research, chinese academy of sciences, beijing 100101, china 2. graduate university of chinese academy of sciences, beijing 100049, china 3. College of Resources Science and Technology, beijing Normal university, beijing 100875, china Institute of Geographic sciences and Natural Resources Research Chinese Academy of Sciences Beijing China graduate university of chinese academy of sciences Beijing China College of Resources Science and Technology Beijing Normal University Beijing China

An integral method,combining support vector ma-chine (SVM) with remote-sensing analysis techniques,was ex-plored to monitor Hanoi’s dynamic change of land cover. The landsat thematic mapper (TM) image in 1993,the enhanced the-matic mapper plus (ETM+) image in 2000,and the image with the charge-coupled device camera (CCD) on the china-Brazil earth resources satellite (CBERS) in 2008 were used. Six land-cover types,including built-up areas,woodland,cropland,sand,water body and unused land,were identified. The detected results showed visually the rapid urban expansion as well as land-cover change of Hanoi from 1993 to 2008. There were 12 637.54 hm2 cropland de-creased between 1993 and 2000,and 8 227.6 hm2 cropland de-creased between 2000 and 2008. Compared with cropland,wood-land firstly decreased and then increased,and the other types did not change significantly. The results indicate that CBERS dataset has the application potential in world resources researches.

关键词： land cover the china-Brazil earth resources satellite (CBERS) support vector machine (SVM) change detection

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The identity of some taxa of Schizophragma (Saxifragaceae)

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Journal of Systematics and Evolution 2009年第2期47卷 151-161页

作者： 1,2Wei LIU 1Xiang-Yun ZHU 1(Institute of Botany,chinese academy of sciences,beijing 100093,china) 2(graduate university of chinese academy of sciences,beijing 100049,china) ( graduate university of chinese academy of sciences Beijing 100049 China )

After examining a large number of type and authoritative specimens of Schizophragma Siebold & Zucc.,*** *** and *** *** Rehder were reduced to synonyms of *** Rehder and *** *** *** was reduced to synonym of *** *** crassum *** *** was treated as the correct name of *** ***(Chun) *** name *** *** Rehder is *** taxonomic treat-ment is supported by leaf epidermal characters.

关键词： leaf epidermis new synonym reinstatement Schizophragma

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Studies on MB-SAR 3D imaging algorithm using Yule-Walker method

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Science china(Information sciences) 2010年第9期53卷 1848-1859页

作者： WANG Bin1,2*,WANG YanPing1,HONG Wen1,TAN WeiXian1,2 & WU YiRong1 1National Key Laboratory of Microwave Imaging Technology,Institute of Electronics,chinese academy of sciences,beijing 100190,china 2graduate university of chinese academy of sciences,beijing 100049,china 1. National Key Laboratory of Microwave Imaging Technology Institute of Electronics Chinese Academy of Sciences Beijing 100190 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

Multibaseline synthetic aperture radar(MB-SAR) can form a synthetic aperture in the height direction with multiple parallel observations,so it has the resolving capability in the height direction and can realize three-dimensional(3D) imaging for the *** analytic model of MB-SAR based on spectrum estimation is analyzed in this *** on the more general geometric model,we derive the signal model for MB-SAR 3D *** then Yule-Walker algorithm is proposed to realize MB-SAR 3D imaging meanwhile the principle is analyzed and the steps of Yule-Walker algorithm are *** algorithm can get the 3D image of the target with high resolution using fewer ***,the experimental results of MB-SAR 3D imaging using Yule-Walker algorithm are presented,which are generated with the simulated data and the data collected in anechoic chamber.

关键词： MB-SAR 3D SAR imaging algorithm SAR spectrum estimation Yule-Walker method

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Microstructure and Wear Resistance Evolution of HVOFSprayed WC-(W,Cr)_2C-Ni Coating with Post Heat Treatment In Air Atmosphere

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稀有金属材料与工程 2012年第S1期41卷 388-393页

作者： Hou Guoliang1,2,Zhou Huidi1,An Yulong1,2,Liu Guang1,2,Chen Jianmin1,Chen Jie1,2 1 State Key Laboratory of Solid Lubrication,Lanzhou Institute of Chemical Physics,chinese academy of sciences,Lanzhou 730000,china 2 graduate university,chinese academy of sciences,beijing 100049,china chinese Acad Sci Lanzhou Inst Chem Phys State Key Lab Solid Lubricat Lanzhou 730000 Peoples R China chinese Acad Sci Grad Univ Beijing 100049 Peoples R China

WC-(W,Cr)2C-Ni coating was prepared on 1Cr18Ni9Ti stainless steel and C-276 Ni-base Hastelloy by high velocity oxy-fuel(HVOF)*** effect of post heat treatment in air atmosphere on the microstructure,phase composition,microhardness,fracture toughness,and wear resistance of HVOF-sprayed WC-(W,Cr)2C-Ni coating was *** microstructure and phase composition of the coatings were analyzed by means of field emission scanning electron microscopy(FESEM)and X-ray diffraction(XRD).The microhardness and fracture toughness of the coatings were measured using a microhardness tester and a Vickers hardness ***,dry friction and wear behavior of the coatings sliding against Si3N4 ball was investigated using an oscillating friction and wear tester;and the worn surfaces of the coatings were analyzed by means of scanning electron microscopy(SEM).It was found that heat treatment within 500-800°C resulted in crystallization of amorphous phase in as-sprayed coating,generating nanoscale new phases such as NiWO4,CrWO4 and ***,heat treatment led to increase of the microhardness of as-sprayed coating,and the highest microhardness was obtained after heat treatment at 800°*** fracture toughness and wear resistance of the as-sprayed coating increased with increasing heat treatment temperature up to 700°C but tended to decrease with further elevating *** other words,the mechanical properties and wear resistance of the as-sprayed coatings were worsened owing to excessive growth of oxidation grains and depletion of ductile Ni binder after heat treatment above 700°*** it was suggested that as-sprayed ceramic composite coating should be post heat treated in air at a moderate temperature of 700°C so as to achieve the optimized mechanical properties and wear resistance.

关键词： HVOF WC-(W,Cr)2C-Ni coating post heat treatment microstructure wear resistance

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Vortex genesis over the Bay of Bengal in spring and its role in the onset of the Asian Summer Monsoon

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Science china Earth sciences 2011年第1期54卷 1-9页

作者： WU GuoXiong1, GUAN Yue1,2, WANG TongMei3, LIU YiMin1, YAN JingHui4 & MAO JiangYu1 1 State Key Laboratory of Numerical Modeling for Atmospheric sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, chinese academy of sciences, beijing 100029, china 2graduate university of chinese academy of sciences, beijing 100049, china 3Department of Atmospheric Science, Sun Yat-Sen university, Guangzhou 510275, china 4National Climate Center, china Meteorological Administration, beijing 100080, china 1. State Key Laboratory of Numerical Modeling for Atmospheric sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. Department of Atmospheric Science Sun Yat-Sen University Guangzhou 510275 China4. National Climate Center China Meteorological Administration Beijing 100080 China

Physical processes associated with onset of the 1998 Asian summer monsoon were examined in detail using multi-source datasets. We demonstrated that strong ocean-atmosphere-land interaction in the northern Indian Ocean and tropical Asian area during spring is a fundamental factor that induces the genesis and development of a monsoon onset vortex over the Bay of Bengal (BOB), with the vortex in turn triggering onset of the Asian summer monsoon. In spring, strong surface sensible heating over India and the Indochina Peninsula is transferred to the atmosphere, forming prominent in situ cyclonic circulation, with anticyclonic circulations over the Arabian Sea and northern BOB where the ocean receives abundant solar radiation. The corresponding surface winds along the North Indian Ocean coastal areas cause the ocean to produce the in situ offshore currents and upwelling, resulting in sea surface temperature (SST) cooling. With precipitation on the Indochina Peninsula increasing from late April to early May, the offshore current disappears in the eastern BOB or develops into an onshore current, leading to SST increasing. A southwest-northeast oriented spring BOB warm pool with SST >31°C forms in a band from the southeastern Arabian Sea to the eastern BOB. In early May, the Somali cross-equatorial flow forms due to the meridional SST gradient between the two hemispheres, and surface sensible heat over the African land surface. The Somali flow overlaps in phase with the anticyclone over the northern Arabian Sea in the course of its inertial fluctuation along the equator. The convergent cold northerlies on the eastern side of the anticyclone cause the westerly in the inertial trough to increase rapidly, so that enhanced sensible heat is released from the sea surface into the atmosphere. The cyclonic vorticity forced by such sensible heating is superimposed on the inertial trough, leading to its further increase in vorticity strength. Since atmospheric inertial motion is destr

关键词： air-sea interaction spring BOB warm pool monsoon onset vortex inertial oscillation Asian summer monsoon onset

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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 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

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Plasmacytoid dendritic cells in antiviral immunity and autoimmunity

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Science china(Life sciences) 2010年第2期53卷 172-182页

作者： TANG Fei1,2,DU Qiumei1,2 & LIU Yong-Jun3 1 Center for Infection and Immunity,Institute of Biophysics,chinese academy of sciences,beijing 100101,china 2 graduate university of chinese academy of sciences,beijing 100049,china 3 Department of Immunology and Center for Cancer Immunology Research,university of Texas,M.D.Anderson Cancer Center,Houston,Texas 77030,USA 1. Center for Infection and Immunity Institute of Biophysics Chinese Academy of Sciences Beijing 100101 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. Department of Immunology and Center for Cancer Immunology Research University of Texas M.D. Anderson Cancer Center Houston Texas 77030 USA

Plasmacytoid dendritic cells (pDCs) represent a unique and crucial immune cell population capable of producing large amounts of type I interferons (IFNs) in response to viral *** function of pDCs as the professional type I IFN-producing cells is linked to their selective expression of Toll-like receptor 7 (TLR7) and TLR9,which sense viral nucleic acids within the endosomal *** I IFNs produced by pDCs not only directly inhibit viral replication but also play an essential role in linking the innate and adaptive immune *** aberrant activation of pDCs by self nucleic acids through TLR signaling and the ongoing production of type I IFNs do occur in some autoimmune ***,pDC may serve as an attractive target for therapeutic manipulations of the immune system to treat viral infectious diseases and autoimmune diseases.

关键词： plasmacytoid dendritic cells type I interferon TLR7 TLR9 antiviral immunity autoimmune diseases

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