检索结果-南通市图书馆

Triaxial ellipsoid models of the Moon based on the laser altimetry data of Chang'E-1

在线全文

学校读者我要写书评

暂无评论

Science China Earth sciences 2010年第11期53卷 1594-1601页

作者： WANG WenRui1,2,3, LI Fei1, LIU JianJun1, REN Xin2, ZOU XiaoDuan2,3, MU LingLi2, YAN JianGuo1, ZOU YongLiao2, ZHANG HongBo2, Lü Chang2, LIU JianZhong2, ZUO Wei2, SU Yan2, WEN WeiBin2, BIAN Wei2, WANG Min2, LI ChunLai2 & OUYANG ZiYuan2 1 school of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China 2 National Astronomical Observatory of chinese academy of sciences, beijing 100012, China 3 graduate school of chinese academy of sciences, beijing 10004., China 1. school of Geodesy and Geomatics Wuhan University Wuhan 430079 China2. National Astronomical Observatory of Chinese Academy of Sciences Beijing 100012 China3. Graduate School of Chinese Academy of Sciences Beijing 100049 China

Lunar geodetic parameters, which play an important role in lunar exploration, can be calculated from the gravity and topography data. With the CE-1 altimetry data and LP gravity model, we calculate such geodetic parameters as the principle moment of inertia, the principle inertia axes, equatorial radius, polar radius, mean radius, flattening and offset between center of mass and center of figure (DCOM-COF). According to the CE-1 altimetry data and the above geodetic parameters, a tri-axial ellipsoid (CE-1-LAM-GEO) and a tri-axial level ellipsoid (CE-1-LAM-LEVEL) are calculated individually, providing mass center and figure center offset (DCOM-COF) and parameters more reliable in direction and magnitude.

关键词： Chang’E-1 laser altimetry data lunar ellipsoid lunar gravity

Validating global hydrological models by ground and space gravimetry

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2009年第9期54卷 1534-1542页

作者： ZHOU JiangCun1,2,3, SUN HePing1,2 & XU JianQiao1,2 1 Institute of Geodesy and Geophysics, chinese academy of sciences, Wuhan 430077, China 2 Key Laboratory of dynamic geodesy, chinese academy of sciences, Wuhan 430077, China 3 graduate University of chinese academy of sciences, beijing 10004., China Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan 430077 China Key Laboratory of dynamic geodesy Chinese Academy of Sciences Wuhan 430077 China graduate University of chinese academy of sciences Beijing 100049 China

The long-term continuous gravity observations obtained by the superconducting gravimeters (SG) at seven globally-distributed stations are comprehensively analyzed. After removing the signals related to the Earth's tides and variations in the Earth's rotation, the gravity residuals are used to describe the seasonal fluctuations in gravity field. Meanwhile, the gravity changes due to the air pressure loading are theoretically modeled from the measurements of the local air pressure, and those due to land water and nontidal ocean loading are also calculated according to the corresponding numerical models. The numerical results show that the gravity changes due to both the air pressure and land water loading are as large as 100×10-9 m s-2 in magnitude, and about 10×10-9 m s-2 for those due to the nontidal ocean loading in the coastal area. On the other hand, the monthly-averaged gravity variations over the area surrounding the stations are derived from the spherical harmonic coefficients of the GRACE-recovered gravity fields, by using Gaussian smoothing technique in which the radius is set to be 600 km. Com-pared the land water induced gravity variations, the SG observations after removal of tides, polar mo-tion effects, air pressure and nontidal ocean loading effects and the GRACE-derived gravity variations with each other, it is inferred that both the ground- and space-based gravity observations can effec-tively detect the seasonal gravity variations with a magnitude of 100×10-9 m s-2 induced by the land water loading. This implies that high precision gravimetry is an effective technique to validate the re-liabilities of the hydrological models.

关键词：重力测量水文模型模型验证和空间地面重力变化季节性波动空气压力

SUSPENDED SEDIMENT TRANSPORT IN THE OFFSHORE NEAR YANGTZE ESTUARY

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2008年第3期20卷 373-381页

作者： CHEN Bin WANG Kai Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China graduate University of the chinese academy of sciences Beijing 100039 China

Based on the Estuarine, Coastal and Ocean Modeling System with Sediments （ECOMSED） model, a 3-D hydrodynamic-transport numerical model was established for the offshore area near the Yangtze Estuary in the East China Sea .The hydrodynamic module was driven by tide and wind. Sediment module included sediment resuspension, transport and deposition of cohesive and non-cohesive sediment. The settling of cohesive sediment in the water column was modeled as a fimction of aggregation （flocculation） and deposition. The numerical results were compared with observation data for August, 2006. It shows that the sediment concentration reduces gradually from the seashore to the offshore area. Numerical results of concentration time series in the observation stations show two peaks and two valleys, according with the observation data. It is mainly affected by tidal current. The suspended sediment concentration is related to the tidal current during a tidal cycle, and the maximum concentration appears 1 h-4 h after the current maximum velocity has reached.

关键词： Yangtze Estuary sediment concentration sediment transport

The biomarkers of 2,6,10,15, 19-pentamethylicosenes and their carbon isotopic composition in the sediments from the Gulf of Mexico

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2006年第14期51卷 1736-1740页

作者： SONG Zhiguang1,2 & WANG Cuiping1,31. State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, chinese academy of sciences, Guangzhou 510640, China 2. Guangzhou Research Center of Gas Hydrate, chinese academy of sciences, Guangzhou 510640, China 3. graduate school of chinese academy of sciences, beijing 100039, China State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China Guangzhou Research Center of Gas Hydrate Chinese Academy of Sciences Guangzhou 510640 China graduate school of chinese academy of sciences Beijing 100039 China

A group of 2,6,10,15,19-pentamethyli- cosenes (PMIΔ) containing 1―5 unsaturated double bonds has been identified in the sea floor sediments from the Gulf of Mexico at the Green Canyon 238 *** PMIΔ compounds are distributed between nC22 and nC24 on the mass chromatogram of aliphatic fraction. Their δ 13C values are very much depleted in 13C and in the range of ?86.7‰ to ?115.5‰, whereas the δ 13C values of companion n-alkanes range from ?28.4‰ to ?34.6‰. These unsaturated PMIΔ com-pounds are typical biomarkers derived from the an-aerobic oxidation of methane mediated by meth-ane-oxidizing archaeal bacteria and indicative of the gas seeps or even the occurrence of gas hydrates in the deep sea sediments.

关键词：生物标志墨西哥湾沉积物 PMIA 天然气水化物

Narrow line Seyfert 1 galaxies: where are the broad line regions?

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2010年第12期53卷 2307-2311,2339-2343页

作者： MAO WeiMing 1,2,3 , HU Chen 2 , WANG JianMin 2 , BIAN WeiHao 4 , ZHANG Shu 2 & ZHAO Gang 1 1 Key Laboratory of Optical Astronomy, National Astronomical Observatories, chinese academy of sciences, beijing 100012, China 2 Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, chinese academy of sciences, beijing 10004., China 3 graduate University of the chinese academy of sciences, beijing 10004., China 4 Department of Physics, Nanjing Normal University, Nanjing 210011, China 1. Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China2. Key Laboratory for Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China3. Graduate University of the Chinese Academy of Sciences Beijing 100049 China4. Department of Physics Nanjing Normal University Nanjing 210011 China

A sample consisting of 211 narrow line Seyfert 1 galaxies (NLS1s) with high quality spectra from the Sloan Digital Sky Survey (SDSS) is selected to explore where broad line regions are in these objects. We find that the Hβ profile can be fitted well by three (narrow, intermediate and broad) Gaussian components, and the FWHM ratios of the broad to the intermediate components hold a constant of 3.0 roughly for the entire sample. If the broad components originate from the region scaled by the well-determined Hβ reverberation mapping relation, we find that the intermediate components originate from the inner edge of the torus, which is scaled by dust K-band reverberation. We find that the IC and the BC are strongly linked dynamically, but the relation of their covering factors is much more relaxed, implying that both regions are clumpy.

关键词： black hole physics galaxies: evolution quasars: general

Research on applying physical chaos generator to spacecraft information security

在线全文

学校读者我要写书评

暂无评论

Science China(Technological sciences) 2009年第5期52卷 1463-1470页

作者： ZHAO HePing State Key Laboratory of Information Security,graduate University of chinese academy of sciences,beijing 10004.,China China academy of Space Technology,beijing 100094,China State Key Laboratory of Information Security Graduate University of Chinese Academy of Sciences Beijing 100049 China China academy of Space Technology Beijing 100094 China

The effectiveness of a short-length message extension method based on physical chaos generator was analyzed and the entropy of the extended message was calculated in this *** analysis demon-strated that with the mentioned method the entropy of short-length messages,which are repeatedly used in spacecraft data systems,is obviously increased,and the security of transmission is enhanced as *** paper also presented an improvement of the protocol for secret key agreement presented by *** and *** of depending on characteristics of communication channel,this method takes advantage of the random data produced by physical chaos generator to preset the initial parameters of the procedure on both sides of communication,so that the procedure and quantity of cipher key can be precisely *** method can be used to cipher key management of se-cure communication between long life-span spacecraft and ground system.

关键词： physical chaos generator spacecraft information security message extension cipher key management

Environmental characteristics of Mid-Holocene recorded by lacustrine sediments from Lake Daihai, north environment sensitive zone, China

在线全文

学校读者我要写书评

暂无评论

Science China Earth sciences 2006年第9期49卷 968-981页

作者： SUN Qianli1,2, ZHOU Jie1, SHEN Ji3, CHEN Peng1,2, WU Feng1,2 & XIE Xiuping1,2 1. State Key Lab of Loess and Quaternary Geology, Institute of Earth Environment, chinese academy of sciences, Xi’an 710075, China 2. graduate University of chinese academy of sciences, beijing 100039, China 3. Nanjing Institute of Geography and Limnology, chinese academy of sciences, Nanjing 210008, China 1. State Key Lab of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi’an 710075 China 2. graduate University of chinese academy of sciences Beijing 100039 China 3. Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Nanjing 210008 China

Climate proxies, such as total organic carbon and nitrogen (TOC, TN), carbonate content (CaCO3), grain-size and pollen of the sediment core retrieved from enclosed Lake Daihai which lies in the north China environment sensitive zone are analyzed to reconstruct the environment evolution of the area based on high-resolution radiocarbon chronology. The results reveal that the TOC and TN contents of the sediments correlate well with pollen percentage and pollen flux variations during the Holocene, and both reach their peak values simultaneously at 6.7―3.5 ka BP (calendar age, 7.6―3.6 ka BP). Since 6.7 ka BP, both the CaCO3 and organic matter contents of the core have simultaneous variations, and their high values also occur during 6.7―3.5 ka BP. While during 9.0―6.7 ka BP (calendar age, 10―7.6 ka BP) relatively lower level of organic matter content and pollen flux corre- spond to the higher level of carbonate content. The above relations suggest that during 6.7―3.5 ka BP, the productivity and effective precipitation were greatly improved in the lake drainage area, and this would probably strengthen the hydrodynamic conditions, enhancing organic matter, pollen and carbonate inputs from terrestrial sources. Such processes would account for the enrichment of both organic matter and carbonate in the sediments. While during 9.0―6.7 ka BP, the lower level of or- ganic matter, pollen flux but high carbonate content show depressed productivity and declined vege- tation coverage. The higher carbonate content at this stage would have probably resulted from the higher evaporation ratio of the lake water under relatively drier climate conditions. Therefore, it is in- ferred that during 6.7―3.5 ka BP, the climate was more humid with abundant rainfalls and vegetation was more flourishing in the Lake Daihai area. This can be seen as Holocene Climate Optimum (HCO). As a result, this has evident discrepancies with the traditional notion that the HCO occurs at Early Holocene or early Mid

关键词： Lake Daihai, Mid-Holocene, lacustrine sediments, environmental characteristics.

Functional Analysis of Multiple Transcription Factor Sites in a Regulatory Element of Human ε-Globin Gene

在线全文

学校读者我要写书评

暂无评论

Acta Biochimica et Biophysica Sinica 2004年第10期36卷 673-680页

作者： Chun-Hui HOU, Jian HUANG, and Ruo-Lan QIAN* State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological sciences, chinese academy of sciences, graduate school of the chinese academy of sciences, Shanghai 200031, China State Key Laboratory of Molecular Biology Institute of Biochemistry and Cell Biology Shanghai Institutes for Biological Sciences Chinese Academy of Sciences Graduate School of the Chinese Academy of Sciences

The developmental control of the human ε-globin gene expression is mediated by transcrip- tional regulatory elements in the 5’ flanking DNA of this gene. A previously identified negative regulatory element (–3028 to –2902 bp, termed ε-NRAII) was analyzed and one putative NF-κB site and two GATA sites locate at –3004 bp, –2975 bp and –2948 bp were characterized. Electrophoresis mobility shift assay (EMSA) showed that the putative NF-κB site was specifically bound by nuclear proteins of K562 cells. Data obtained from transient transfection showed that the expression of reporter gene could be upregulated about 50% or 100% respectively when ε-NRAII was inserted upstream of the SV40 promoter or ε-globin gene proximal promoter (–177 bp to +1 bp), suggesting that ε-NRAII might not be a classic silencer. Mutation in the putative NF-κB site or in the GATA site (at –2975 bp) slightly reduced the expression of reporter gene driven by SV40 promoter or ε-globin gene proximal promoter. However, the mutation of GATA site at –2948 bp remarkably reduced the reporter gene activity driven by SV40 promoter, but not by ε-globin gene proximal promoter. Further mutation analysis showed that the negative effect of mutation in GATA site at –2948 bp on SV40 promoter was not affected by the mutation of the putative NF-κB site, whereas it could be abolished by the mutation of GATA site at –2975 bp. Furthermore, the mutation of both GATA sites could synergistically reduce the reporter gene activity driven by ε-globin gene proximal promoter. Those results suggested that ε- NRAII might function differently on the SV40 promoter and ε-globin gene proximal promoter.

关键词： ε-globin gene regulatory element NF-κB GATA

Properties and applications of cold supersonic gas jet

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2006年第6期49卷 709-715页

作者： ZHANG Shaofeng1,2,MA Xinwen1,2,LIU Huiping2,LI Bin1,2 & ZHU Xiaolong1,2 1. Institute of Modern Physics,chinese academy of sciences,Lanzhou 730000,China 2. graduate University of chinese academy of sciences,beijing 10004.,China 1. Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China 2. graduate University of chinese academy of sciences Beijing 100049 China

By analyzing the formation mechanism of a supersonic gas jet,a set of equations which describe the atomic beam properties were established. The influence of initial temperature,initial pressure,background gas pressure and pumping speed was discussed in detail. A simulation program was developed based on the equations,and the results under different initial conditions were obtained. The results are in good agreement with the experimental data,and suggest that,in order to get much smaller transverse momentum in collision experiments,it is necessary to lower the initial temperature and the initial pressure of the supersonic gas jet,together with increasing the pumping speed. These results are very instructive for construction of a new generation of cold supersonic gas jets.

关键词： cold supersonic gas jet,zone of silence,nozzle,skimmer.