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An Alternative Explanation for a Screw-like Meteoric Train Photographed by Double-Station Observations

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chinese Journal of Astronomy and Astrophysics 2007年第6期7卷 814-822页

作者： Guang-Jie Wu1,2.1 National Astronomical Observatories/Yunnan Observatory,chinese academy of {2.,Kunming 650011 2.Purple Mountain Observatory,chinese academy of {2.,Nanjing 2.0008 Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008

Two-station observation of meteors, especially a meteor trains, provides an effective approach to the measurement of the physical parameters. We have collected four special groups of photographs of meteoric trains taken at two stations during Leonids 2.01. One representative group has been measured and analyzed in detail. An analysis has been reported in our first paper. In this paper, an alternative explanation for the screw-like meteoric train is suggested based on some physical calculations. The results reveal that this train has a screw-like structure and, apparently, spoke beams. The mother meteor of this train may be negatively charged and moves forward along a left-hand screw trajectory under the effect of the geomagnetic field. The spoke beams might be the visual effect of the long time exposure of many particles released from the disintegrated meteoroid.

关键词： meteors meteoroids -- magnetic fields

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.,Beijing 100012.China 2.Graduate School of chinese academy of sciences,Beijing 100049,China National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Graduate School of chinese academy of sciences Beijing 100049 China

We used the Sloan Digital Sky Survey （SDSS） Data Release 5 （DR5） to study the morphological properties of 1137 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 39%.

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

SHRIMP zircon U-Pb geochronology of early Mesozoic felsic igneous rocks from the southern Lancangjiang and its tectonic implications

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Science China Earth sciences 2006年第10期49卷 1032-1042页

作者： PENG Touping1,2. WANG Yuejun1, FAN Weiming1, LIU Dunyi3, SHI Yuruo3 & MIAO Laicheng4 1. Key Laboratory of Isotope Geochronology and Geochemistry, Guangzhou Institute of Geochemistry, chinese academy of sciences, Guangzhou 510640, China 2. Graduate University of chinese academy of sciences, Beijing 100039, China 3. SHRIMP isotope Laboratory, {2. academy of Geological sciences, Beijing 100037, China 4. Institute of Geology and Geophysics, chinese academy of sciences, Beijing 10002., China Key Laboratory of Isotope Geochronology and Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China Graduate University of chinese academy of sciences Beijing China SHRIMP isotope Laboratory Chinese Academy of Geological Sciences Beijing China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China

The SHRIMP zircon U-Pb geochronology of three typical samples, including two monzo nitic granites from the Lincang batholith and a rhyolite from the Manghuai Formation are presented in the southern Lancangjiang, western Yunnan Province. The analyses of zircons for the biotite monzonitic granites from the northern (02.X-137) and southern (2.JH-10) Lincang batholith show the single and tight clusters on the concordia, and yield the weighted mean 2.6Pb/2.8U ages of 2.9.4 ± 3.0 Ma and 2.0.4 ± 3.6 Ma, respectively, representing the crystallized ages of these granites. The zircons for the rhyolitic sample (02.X-95) from the Manghuai Formation give a weighted mean 2.6Pb/2.8U age of 2.1.0 ± 5.0 Ma. These data suggest that the igneous rocks from the Lincang granitic batholith and Manghuai Formation have a similar crystallized age. In combination with other data, it is inferred that both were generated at a narrow age span (~2.0 Ma) and were originated from the postcollisional tectonic regime. An early Proterozoic 2.6Pb/2.8U apparent age of 1977±44 Ma is additionally obtained from one zircon from the biotite monzonitic granite (southern Lincang batholith), indicative of devel- opment of the early Proterozoic Yangtze basement in the region. These precisely geochronological data provide important constraints on better understanding the Paleozoic tectonic evolution of the Tethys, western Yunnan Province.

关键词： SHRIMP zircon U-Pb dating, Middle Triassic, Lincang granitic batholith, Manghuai Formation rhyolite, southern Lancangjiang.

THE STEP-TRANSITION OPERATORS FOR MULTI-STEP METHODS OF ODE'S

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Journal of Computational Mathematics 1998年第3期16卷 193-202页

作者： Feng K.(ICMSEC, chinese academy of sciences) 中科院计算数学与科学工程计算所北京

In this paper, we propose a new definition of symplectic multistep methods. This definition differs from the old ones in that it is given via the one step method defined directly on M which is corresponding to the m step scheme defined on M while the old definitions are given out by defining a corresponding one step method on M × M ×…× M = Mm with a set of new variables. The new definition gives out a steptransition operator g: M → M. Under our new definition, the Leap-frog method is symplectic only for linear Hamiltonian systems. The transition operator g will be constructed via continued fractions and rational approximations.

关键词： Multi-step methods Explike and loglike function Fractional and rational approximation Simplecticity of LMM Nonexistence of SLMM.

Estimation on dynamic release of phosphorus from wind-induced suspended particulate matter in Lake Taihu

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Science China Earth sciences 2004年第8期47卷 710-719页

作者： FAN Chengxin1, ZHANG Lu1,2. QIN Boqiang1, WANG Sumin1, HU Weiping1 & ZHANG Chen1 1. Taihu Lake Laboratory for Ecosystem Research, Nanjing Institute of Geography & Limnology, chinese academy of sciences, Nanjing 2.0008, China 2. Graduate School of chinese academy of sciences, Beijing 100039, China 1. Taihu Lake Laboratory for Ecosystem Research Nanjing Institute of Geography & Limnology Chinese Academy of Sciences 210008 Nanjing China 2. Graduate School of chinese academy of sciences 100039 Beijing China

Through man-made disturbance experiments, the corresponding relationships be-tween suspended particulate matter (SPM) and wind speed in different lake areas were simu-lated, the physicochemical formal transformation and biological mineralizing and decaying processes of phosphorus in SPM were studied, the contribution of phosphorus transformation to phosphorus loading of the water of Lake Taihu was quantitatively estimated. The results show that about 0.44 t·a-1 loading in Lake Taihu mainly comes from phosphorus-releasing action of SPM in physicochemical transformed to soluble reactive phosphorus (SRP), and the contribution mainly from biological mineralizing and decaying was about 42..8 t·a-1, which is equal to 15.0% of the total external loading of Lake Taihu, namely 4.7—7.5 times as much as SRP loading en-tering the lake by the rivers; thus it is the important source in dynamical internal loading of the lake. The determining factors for dynamical internal loading in lakes are organic phosphorus content in suspended solid and its biological transition availability.

关键词： phosphorus release,wind wave disturbance,particulate decaying,dynamical loading,Lake Taihu.

Paleoenvironments indicated by the fossil mammalian assemblages from red clay-loess sequence in the chinese Loess Plateau since 8.0 Ma B.P.

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Science China Earth sciences 2006年第5期49卷 518-530页

作者： XUE Xiangxu1,2. ZHANG Yunxiang1,2.& YUE Leping1,2.1. State Key Laboratory of Continent Dynamics (Northwest University), Institute of Cenozoic Geology and Environment, De- partment of Geology, Northwest University, Xi’an 710069, China 2. Institute of Earth Environment, State Key Laboratory of Loess and Quaternary Geology, chinese academy of sciences, Xi’an 710075, China 1. State Key Laboratory of Continent Dynamics (Northwest University) Institute of Cenozoic Geology and Environment Department of Geology Northwest University Xi’an 710069 China 2. Institute of Earth Environment State Key Laboratory of Loess and Quaternary Geology Chinese Academy of Sciences Xi’an 710075 China

Information from eleven profiles of eolian earthy red silty clay and loess of the middle of the Late Miocene to Holocene age have been studied and correlated. A complete summary profile with projected isotopic ages and fossil-bearing beds has been assembled. The profile is subdivided into 12.stratigraphic units proceeding from the lower (older) to the upper (younger) one. The character of mammalian assemblages contained in each unit was analyzed and the corresponding pa- leo-climatic environments were deduced. The environmental character of each period and the change from the middle of the Late Miocene at about 8.0 Ma B.P. up to the Holocene progressed from the hot semiarid and semi-moist, warmer-moist, warm-moister of the Late Miocene. To slightly less warm moist, cool-dry, slight-warmer-moister of the Pliocene; later the cool to cold dry periods alternated frequently with the mild semiarid and semi-moist periods of the Quaternary. Vegetation progressed from the grasslands with sparse woods, wooded shrub-grasslands and subtropical forest-grasslands of the Late Miocene age to sparse grasslands and dry grasslands of the Pliocene; and to sparse grasslands, dry grasslands and tundras of the Quaternary. The climate changes in the Neogene were of low-amplitute in a generally warm-humid background. Those of the Quaternary were of higher am- plitude with a longer phase. Cool or cold dry and slightly warm semiarid and semi-moist climates al- ternated on a generally cool-dry background. The tendency since the start of the Quaternary was the change to more northern and western shift in the Loess Plateau, with progressively cooler and dryer conditions. The dramatic uplift of the Qinghai-Xizang (Tibet) Plateau and the forming and expansion of the Arctic ice sheet might be the main reasons of the more pronounced changes in the Quaternary.

关键词： paleoenvironment, mammalian fossils, eolian red clay-loess sequence, Loess Plateau.

Statistical distribution of nonlinear random wave height

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Science China Earth sciences 2006年第4期49卷 443-448页

作者： HOU Yijun1, GUO Peifang1,2. SONG Guiting1,2. SONG Jinbao1, YIN Baoshu1 & ZHAO Xixi1,2.1. Institute of Oceanology, chinese academy of sciences, Qingdao 2.6071, China 2. Graduate University of the chinese academy of sciences, Beijing 100039, China 1. Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China 2. Graduate University of the chinese academy of sciences Beijing 100039 China

A statistical model of random wave is developed using Stokes wave theory of water wave dynamics. A new nonlinear probability distribution function of wave height is presented. The results indicate that wave steepness not only could be a parameter of the distribution function of wave height but also could reflect the degree of wave height distribution deviation from the Rayleigh distribution. The new wave height distribution overcomes the problem of Rayleigh distribution that the prediction of big wave is overestimated and the general wave is underestimated. The prediction of small probability wave height value of new distribution is also smaller than that of Rayleigh distribution. Wave height data taken from East China Normal University are used to verify the new distribution. The results in- dicate that the new distribution fits the measurements much better than the Rayleigh distribution.

关键词： Random ocean wave, nonlinearity, wave height distribution.

Modeling and verifying Web services driven by requirements:An ontology-based approach

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Science in China(Series F) 2006年第6期49卷 792-820页

作者： HOU Lishan1,3,JIN ZHi1,2.& WU Budan1,4 1. academy of Mathematics and Systems Science, chinese academy of sciences, Beijing 100080, China 2. Institute of Computing Technology, chinese academy of sciences, Beijing 100080, China 3. Institute of Software, chinese academy of sciences, Beijing 100080, China 4. Graduate University of chinese academy of sciences, Beijing 100049, China 1. academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China 3. Institute of Software Chinese Academy of Sciences Beijing 100080 China 2. Institute of Computing Technology Chinese Academy of Sciences Bejing 100080 China 4. Graduate University of chinese academy of sciences Beijing 100049 China

Automatic discovery and composition of Web services is an important research area in Web service technology, in which the specification of Web services is a key issue. This paper presents a Web service capability description framework based on the environment ontology. This framework depicts Web services capability in two aspects： the operable environment and the environment changes resulting from behaviors of the Web service. On the basis of the framework, a requirement-driven Web service composition model has been constructed. This paper brings forward the formalization of Web service interactions with π calculus. And an automatic mechanism converting conceptual capability description to the formal process expression has been built. This kind of formal specification assists in verifying whether the composite Web service model matches the requirement.

关键词： Web service environment ontology automatic composition π calculus formal verification.

Improvement of different source function expressions in SWAN model for the Bohai Sea

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Progress in Natural Science:Materials International 2005年第8期15卷 720-724页

作者： YIN Baoshu1*, YANG Dezhou1, SHA Rina 1,2.and CHENG Minghua1(1. Institute of Oceanology, chinese academy of sciences, Qingdao 2.6071, China 2. Graduate School of the chinese academy of sciences, Beijing 100039, China) Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China. Graduate School of the chinese academy of sciences Beijing 100039 China

The simulating wave nearshore （SWAN） wave model has been widely used in coastal areas, lakes and estuaries. However, we found a poor agreement between modeling results and measurements in analyzing the chosen four typical cases when we used the default parameters of the source function formulas of the SWAN to make wave simulation for the Bohai Sea. Also, it was found that at the same wind process the simulated results of two wind generation expressions （Komen, Janssen） demonstrated a large difference. Further study showed that the proportionality coefficient α in linear growth term of wave growth source function plays an unperceived role in the process of wave development. Based on experiments and analysis, we thought that the coefficient α should change rather than be a constant. Therefore, the coefficient α changing with the variation of friction velocity U*was introduced into the linear growth term of wave growth source function. Four weather processes were adopted to validate the improvement in the linear growth term. The results from the improved coefficient α agree much better with the measurements than those from the default constant coefficient α. Furthermore, the large differences of results between Komen wind generation expression and Janssen wind generation expression were eliminated. We also experimented with the four weather processes to test the new white-capping mechanisms based on the cumulative steepness method. It was found that the parameters of the new white-capping mechanisms are not suitable for the Bohai Sea, but Alkyon's white-capping mechanisms can be applicable to the Bohai Sea after amendments, demonstrating that this improvement of parameter α can improve the simulated results of the Bohai Sea.

关键词： waves SWAN model wave growth source function new proportionality coefficient formula.