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Spectral analysis of quasi-stationary sea surface topography from GRACE mission

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Science china Earth sciences 2005年第11期48卷 2040-2048页

作者： ZHANG Zizhan1,2.& LU Yang1,3.1. Institute of Geodesy and Geophysics, chinese academy of {2., Wuhan 43.077, china 2. graduate school of the chinese academy of {2., beijing 10003., china 3. Unite Center for Astro-geodymics Research, chinese academy of {2., Shanghai 2.003., china 1. Institute of Geodesy and Geophysics Chinese Academy of Sciences 430077 Wuhan China 2. graduate school of the {2. academy of sciences 100039 Beijing China 3. Unite Center for Astro-geodymics Research Chinese Academy of Sciences 200030 Shanghai China

During the last two decades satellite altimetry has offered an abundance of meas-urements of the sea surface resulting in the improvement of global mean sea surface height (MSSH) and marine geoid determination. On the other hand, with the launching of new genera-tion gravity satellites, some high accuracy long-wavelength gravity models are available. These breakthroughs give us a great opportunity for new estimation of quasi-stationary sea surface topography (QSST). In this paper, the new gravity model GGM01C derived from GRACE mission is briefly presented, and a new global high precision and high-resolution QSST is determined based on the GGM01C model and the global MSSH. The spectral features of the QSST esti-mated by GGM01C and EGM96 gravity model to degree/order 2.0 are discussed by spectral analysis. As a result, the QSST is mainly composed of long waves, medium waves partially and short waves scarcely, its power spectral structures are different between the zonal direction and the meridional direction, there are great differences between the two models, which maybe ex-plain why the ocean currents derived from the two gravity models by Tapley show different pat-terns.

关键词： quasi-stationary sea surface topography, mean sea surface height, GGM01, fast Fourier transform, spectral analysis

Variation properties of ionospheric eclipse factor and ionospheric influence factor

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Progress in Natural Science:Materials International 2005年第6期15卷 573-576页

作者： ZHAO Chunmei 1,2.*, YUAN Yunbin1, OU Jikun1 and CHEN Jinping3.1. Institute of Geodesy and Geophysics, chinese academy of {2., Wuhan 43.077, china 2. graduate school of chinese academy of sciences, beijing 10003., china 3. Department of Precision Instrument and Mechanology, Tsinghua University, beijing 100084, china) Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan 430077 China graduate school of {2. {3. of sciences Beijing 100039 China Department of Precision Instrument and Mechanology Tsinghua University Beijing 100084 China

The concepts and calculation methods of ionospheric eclipse factor (IEF) and ionospheric influence factor (IFF) are further illustrated. The temporal and spacial variation properties of IEF and IFF are studied, which shows that the properties are influenced by the geographic position and season. The possibility of improving the precision of using GPS data to determine ionospheric delay based on the above variation properties is also analysed.

关键词： GPS ionospheric eclipse factor ionospheric influence factor

Relationships between tree-ring width index and NDVI of grassland in Delingha

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chinese Science Bulletin 2006年第9期51卷 1106-1114页

作者： HE Jicheng1,3.& SHAO Xuemei1,2.. Institute of Geographical sciences and Natural Resources Research, chinese {2. of sciences, beijing 100101, china 2. Institute of Tibetan Plateau Research, chinese {2. of sciences, beijing 100085, china 3. {13. {12. of chinese {2. of sciences, beijing 10003., china Institute of Geographical sciences and Natural Resources Research Chinese Academy of Sciences Beijing China graduate school of {2. {3. of sciences Beijing China Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China

Using five well-replicated Qilian juniper (Sabina przewalskii Kom.) tree-ring width index se- ries, monthly normalized difference vegetation index (NDVI) of grassland, and climatic data from 1982.to 2.01, the relationships between tree-ring width index, NDVI of grassland, and climatic data were analyzed firstly. Then, the relationship between tree-ring width index and NDVI of grassland was explored. The re- sults showed that: (1) Temperature and precipitation in June influenced tree-ring width index and NDVI of grassland deeply in Delingha. (2. There were sig- nificant relationships between five tree-ring width index series (DLH1-DLH5) and monthly NDVI of grassland from June to September, with the most significant relationship being between tree-ring width index series and NDVI of grassland in August. (3. The PC1 (the first principal component derived from DLH1-DLH5 series) exhibited good agreement with monthly NDVI of grassland in the grass growth sea- son (from June to September) and the averaged NDVI in the growth season, which was attributed to their common responses to water-supply limit in Delingha. This study may allow an increase in studying the past dynamics of grassland in Delingha in that the variation of grassland NDVI during the last millennium has been reconstructed from PC1.

关键词：圆柏祁连山 NDVI 草原年轮宽度指数

Debris Flow Hazard Assessment Based on Support Vector Machine

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Wuhan University Journal of Natural sciences 2006年第4期11卷 897-900页

作者： YUAN Lifeng 1, 2., ZHANG Youshui 3. 1. Institute of Mountain Hazards and Environment, chinese academy of {2., Chengdu 610041, Sichuan, china 2. graduate University of chinese academy of {2., beijing 100049, china 3. Institute of Geographical {2. and Natural Resources Research, chinese academy of {2., beijing 100101, china Institute of Mountain Hazards Environment Chinese Academy of Sciences 610041 Chengdu Sichuan China graduate University of chinese {2. of {3. 100049 Beijing China Institute of Geographical sciences Natural Resources Research Chinese Academy of Sciences 100101 Beijing China

Seven factors, including the maximum volume of once flow , occurrence frequency of debris flow , watershed area , main channel length , watershed relative height difference , valley incision density and the length ratio of sediment supplement are chosen as evaluation factors of debris flow hazard degree. Using support vector machine （SVM） theory, we selected 2.9 basic data of 3. debris flow channels in Yunnan Province as learning samples in this study. We create a debris flow hazard assessment model based on SVM. The model was validated though instance applications and showed encouraging results.

关键词： debris flow hazard assessment support vector machine (SVM)

Integrated precise orbit determination of Shenzhou IV unmanned spacecraft

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Science china(Technological sciences) 2004年第5期47卷 518-525页

作者： L Congmin1,2. GU Yidong3. LIN Baojun3.& GUO Jiong3.1. Center for Space Science and Applied Research, chinese academy of {2., beijing 100080, china 2. graduate school of the chinese academy of {2., beijing 10003., china 3. General Establishment of Space Science and Application, chinese academy of {2., beijing 100080, china Correspondence should be addressed to L Congmin 1. Center for Space Science and Applied Research Chinese Academy of Sciences 100080 Beijing China 2. graduate school of the {2. academy of sciences 100039 Beijing China 3. General Establishment of Space Science and Application Chinese Academy of Sciences 100080 Beijing China

Considering the characteristic orbit of Shenzhou IV spacecraft and the advantages and disadvantages of several types of domestic orbit measurements, a scheme of IPOD is determined, which uses GPS, SLR and USB observation data jointly plus precise ionosphere corrections to GPS observation data. IPOD system and mathematic models of OD are introduced. The results of different joint OD are analyzed using true observation data, and show that radial accuracy is better than 2.m.

关键词： Shenzhou IV unmanned spacecraft integrated precise orbit determination GPS SLR USB.

Infrared Galaxies in the Nearby Universe

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chinese Journal of Astronomy and Astrophysics 2008年第6期8卷 643-652页

作者： Jian-Ling Wang 1 National Astronomical Observatories,chinese academy of {2.,{3. 100012.china 2.graduate school of chinese academy of {2.,{3. 100049,china National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China graduate school of {2. {3. of sciences Beijing 100049 China

We used the Sloan Digital Sky Survey （SDSS） Data Release 5 （DR5） to study the morphological properties of 113. nearby infrared （IR） galaxies, most of which are brighter than 15.9 mag in r-band. This sample was drawn from a cross-correlation of the Infra-Red Astronomical Satellite （IRAS） point source catalog redshift survey with DR5 at z ≤ 0.08. Based on this IR galaxy sample, we constructed five volume-limited sub-samples with IR luminosity ranging from 10^9.5 L⊙ to 10^12.⊙. By deriving the IR luminosity functions （LF） for different morphological types, we found that normal spiral galaxies are the dominant population below LIR ~ 8 ~ 10^10 L⊙; while the fraction of barred spiral galaxies increases with increasing IR luminosity and becomes dominant in spiral galaxies beyond LIR ≈ 5 × 10^10L⊙. As the IR luminosity decreases, the IR galaxies become more compact and have lower stellar masses. The analysis also shows that normal spiral galaxies give the dominant contribution to the total comoving IR energy density in the nearby universe, while, in contrast, the contribution from peculiar galaxies is only 3.%.

关键词： galaxies evolution galaxies interactions galaxies starburst infrared galaxies galaxies luminosity function

Analysis of tandem repeats in the genome of chinese shrimp Fenneropenaeus chinensis

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chinese Science Bulletin 2005年第14期50卷 1462-1469页

作者： KONG Jie1 & GAO Huan2.3.1. Key Laboratory for Sustainable Utilization of Marine Fisheries Re- sources, Ministry of Agriculture, Yellow Sea Fisheris Research Insti- tute, chinese academy of Fishery {2., Qingdao 2.6071, china 2. Institute of Oceanology, chinese academy of {2., Qingdao 2.6071, china 3. The graduate {13. of the chinese academy of {2., beijing 10003., china Key Laboratory for Sustainable Utilization of Marine Fisheries Resources Ministry of Agriculture Yellow Sea Fisheris Research Institute Chinese Academy of Fishery Sciences Qingdao China Institute of Oceanology Chinese Academy of Sciences Qingdao China The graduate school of the {2. {3. of sciences Beijing China

Through random sequencing, we found a total of 884000 base-pairs (bp) of random genomic sequences in the genome of chinese shrimp (Fenneropenaeus chinensis). Using bio-soft Tandem Repeat Finder (TRF) software, 2.59 tandem repeats were found, in which there were 1714 mi- crosatellites and 445 minisatellites, accounting for 79.4% and 2..6% of repeat sequences, respectively. The cumulative length of repeat sequences was found to be 116685 bp, ac- counting for 13.2. of the total DNA sequence; the cumula- tive length of microsatellites occupied 9.78% of the total DNA sequence, and that of minisatellites occupied 3.42.. In decreasing order, the 2. most abundant repeat sequence classes were as follows: AT (557), AC (471), AG (2.4), AAT (92., A (56), AAG (2.), ATC (2.), ATAG (2.), AGG (18), ACT (15), C (11), AAC (11), ACAT (11), CAGA (10), AGAA (9), AGGG (7), CAAA (7), CGCA (6), ATAA (6), AGAGAA (6). Dinucleotide repeats, not only in the aspect of the number, but also in cumulative length, were the preponderant repeat type. There were few classes and low copy numbers of repeat units of the pentanucleotide repeat type, which included only three classes: AGAGA, GAGGC and AAAGA. The classes and copy numbers of heptanucleotide, eleven-nucleotide and thirteen-nucleotide primer-number-composed repeats were distinctly less than that of repeat types beside them.

关键词：虾遗传特性遗传基因 DNA

Representation of microscale ocean wavenumber spectrum correct to the second order

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Science china Earth sciences 2005年第4期48卷 549-554页

作者： YUAN Yeli2.& HUA Feng1,2.3.1. Institute of Oceanology, chinese {3. of {2., Qingdao 2.6071, china 2. Key Laboratory of Marine Science and Numerical Modeling, State Oceanic Administration, Qingdao 2.6061, china 3. graduate school of the chinese {3. of {2., beijing 10003., china 1. Key Laboratory of Marine Science and Numerical Modeling State Oceanic Administration 266061 Qingdao China 2. Institute of Oceanology Chinese Academy of Sciences 266071 Qingdao China 3. graduate school of the {2. {3. of sciences 100039 Beijing China

In this paper, the analytical representations of four wave source functions in high-frequency spectrum range are given on the basis of ocean wave theory and dimensional analysis, and the perturbation method is used to solve the governing equations of ocean wave high-frequency spectrum on the basis of the temporally stationary and locally homogeneous scale relations of microscale wave. The microscale ocean wavenumber spectrum correct to the second order has an explicit structure, its first order part represents the equilibrium between dif- ferent source functions, and its second order part represents the contribution of microscale wave propagation.

关键词： temporally stationary and locally homogeneous, source function in high-frequency spectrum range, microscale ocean wavenumber spectrum.

Effect of rock mass structure and block size on the slope stability——Physical modeling and discrete element simulation

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Science china(Technological sciences) 2005年第z1期48卷 1-17页

作者： LI Shihai1, LIAN Zhenzhong1,2.& J. G. Wang3.1. Institute of Mechanics, chinese academy of {2., beijing 100080, china 2. graduate school, chinese academy of {2., beijing 100060, china 3. Tropical Marine Science Institute, National University of Singapore, Singapore 1192.0 chinese Acad Sci Inst Mech Beijing 100080 Peoples R China chinese Acad Sci Grad Sch Beijing 100060 Peoples R China Natl Univ Singapore Trop Marine Sci Inst Singapore 119260 Singapore

This paper studies the stability of jointed rock slopes by using our improved three-dimensional discrete element methods (DEM) and physical modeling. Results show that the DEM can simulate all failure modes of rock slopes with different joint configurations. The stress in each rock block is not homogeneous and blocks rotate in failure development. Failure modes depend on the configuration of joints. Toppling failure is observed for the slope with straight joints and sliding failure is observed for the slope with staged joints. The DEM results are also compared with those of limit equilibrium method (LEM). Without considering the joints in rock masses, the LEM predicts much higher factor of safety than physical modeling and DEM. The failure mode and factor of safety predicted by the DEM are in good agreement with laboratory tests for any jointed rock slope.

关键词： rock masses, slope stability, DEM simulation, block size effect, joints configuration effect, limit equilibrium method.