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Propagation of interplanetary shock excited ultra low frequency (ULF) waves in magnetosphere-ionosphere-atmosphere——Multi-spacecraft “Cluster” and ground-based magnetometer observations

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Science china(Technological sciences) 2010年第9期53卷 2528-2534页

作者： WANG ChengRui1,2,ZONG QiuGang1,3 & WANG YongFu1 1 Institute of Space Physics and Applied Technology,peking university,beijing 100871,china 2 Sate Key Laboratory of Space Weather,chinese academy of sciences,beijing 100190,china 3 center for Atmospheric Research,600 Suffolk Street,university of Massachusetts Lowell,MA 01854,USA Institute of Space Physics and Applied Technology Peking University Sate Key Laboratory of Space Weather Chinese Academy of Sciences center for Atmospheric Research 00 Suffolk Street University of Massachusetts Lowell

The ultra low frequency (ULF) wave in magnetosphere can act as an important means for solar wind energy inward *** paper quantitatively analyzes the propagation process of the ULF wave triggered by the interplanetary shock propagating from inner magnetosphere equatorial plane along magnetic field lines to the top of the ionosphere and below ionosphere propagating process and establishes a relatively complete magnetosphere-ionosphere-atmosphere propagation model which can be used to study the relationship between the amplitude of the ULF waves triggered by the interplanetary shock wave in magnetospheric space and the magnetic effect caused by the ULF *** a comparison with recent observations,we found that: in the event during November 7,2004 that an interplanetary shock wave interacted with the magnetosphere,Cluster satellites observed that electric field fluctuations and the band-pass filtered result of ground stations meridional component had similar *** with the geomagnetic measurement near the footprints,we found that the electric field disturbance in the magnetosphere spread along the ground magnetic field lines in the form of the ULF waves and changed into geomagnetic *** result reveals that the ULF wave is in contact with the ground geomagnetic *** ULF waves couple with ionized components in ionosphere and spread to the ground in the form of electromagnetic *** this research,we believe that the magnetosphere,ionosphere and ground magnetic effects caused by interplanetary shock wave are the same physical phenomena responding in different *** on the overall consideration of entire electromagnetic response to the interplanetary shock wave,we found that the correlation between CLUSTER multi-satellite observation and geomagnetic station observation is due to the ULF wave propagated in magnetosphere-ionosphere-atmosphere system,and we quantitatively interpreted this response process

关键词： ultra low frequency (ULF) wave magnetic storm ionosphere IRI model interplanetary shock

Contributions of different land cover types in Otindag Sandy Land and Bashang area of Hebei Province to the material source of sand stormy weather in beijing

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chinese Science Bulletin 2003年第17期48卷 1853-1856页

作者： LIU Hongyan, TIAN Yuhong & DING Deng Department of Ecology, College of Environmental sciences, peking university, beijing 100871, china Department of Ecology College of Environmental Sciences Peking University Beijing 100871 China

Different land cover types in Otindag Sandy Land and Bashang area of Hebei Province are linked to a material source of sand stormy weather in beijing based on results of field vegetation and soil survey and laboratory works. Results of grain size analysis show that dust release potential in per unit area of moving sandy land is small, while lowland meadow and meadow steppe in stony hills have high potential of releasing dusts in per unit area during sand stormy weather occurrence. Further considering the effects of vegetation, it is inferred that the moving sandy land served as a material source of past dust storm and the possi-bility of dust release in per unit area is low in current time. Typical steppe in stony hills is undergoing desertification and its dust release possibility in per unit area is high. Farmland has strong potential of release dusts when they are ploughed in spring, but a large amount of therophytes grow and thus prevent dusts from release when cultivation was terminated. Potentials of dust release in per unit area in fixed sand dunes, stony mountain meadow steppe and lowland meadow are low due to high cover of perennials. Sand dune reactivation and desiccation of lakes and lowlands under estimated future climatic change will make them serve as a future material source of sand stormy weather.

关键词：河北北京沙暴土地覆盖砂地坝上地区材料源

Progress in multi-waveband observations of supernova remnants

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Progress in Natural Science:Materials International 2008年第9期18卷 1057-1062页

作者： Xuejuan Yang a,b, Fangjun Lua, Wenwu Tian c,d,* a Particle astrophysics center, Institute of High Energy Physics, chinese academy of sciences, beijing 100049, china b Department of Astronomy, beijing Normal university, beijing 100875, china c National Astronomical Observatories, chinese academy of sciences, 20A Datun Road, Chaoyang District, CAS, beijing 100012, china d Department of Physics & Astronomy, university of Calgary, Alberta, Canada T2N 1N4 Particle astrophysics center Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China Department of Astronomy Beijing Normal University Beijing 100875 China National Astronomical Observatories Chinese Academy of Sciences 20A Datun Road Chaoyang District CAS Beijing 100012 China Department of Physics & Astronomy University of Calgary Alberta Canada T2N 1N4

The development of observational techniques has enriched our knowledge of supernova remnants. In this paper, we review the main progresses in the last decade, including new discoveries of supernova remnants and the associated (rare type of) pulsars, nucleosynthesis, the interaction between supernova remnants and molecular clouds, dust in the supernova remnants, shock physics, and cosmic ray accelerations.

关键词： Supernova remnant Observations

Bifurcation timescales in power spectra of black hole binaries and ultraluminous X-ray sources

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 177-182页

作者： WANG TaiShan1 & LI TiPei1,2 1 Department of Physics & center for astrophysics,Tsinghua university,beijing 100084,china 2 Key Laboratory of Particle astrophysics,Institute of High Energy Physics,chinese academy of sciences,beijing 100049,china Department of Physics & center for astrophysics Tsinghua University Beijing China Key Laboratory of Particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing China

For black hole binaries(BHBs) and active galactic nuclei(AGNs),bifurcation timescales(BTs) Δtb exist,below which time-domain power is significantly higher than the corresponding Fourier ***-periodic oscillations(QPOs) are removed from the Fourier spectra of BHBs.A relationship between BT,black hole mass and bolometric luminosity is *** anti-correlation between BT and luminosity of Cyg X-1 is *** removing the QPOs,BTs are also obtained for two ultraluminous X-ray sources(ULXs),M82 X-1 and NGC5408 *** results support that they harbor intermediate mass black holes(IMBHs).

关键词： black hole binary ultraluminous X-ray source power spectral density data analysis

Uniform design over a convex polyhedron

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chinese Science Bulletin 1999年第2期44卷 112-114页

作者： FANG Kaitai , TIAN Guoliang XIE Minyu Hong Kong Baptist university, Kowloon, Hong Kong, china Institute of Applied Mathematics, chinese academy of sciences, beijing 100080, china Central china Normal university, Wuhan 430070, chinaCorresponding author: Present address: Department of Probability and Statistics, peking university, beijing 100871, china Hong Kong Baptist university Hong Kong China Institute of Applied Mathematics Chinese Academy of Sciences Beijing China Central china Normal university Wuhan China

A new method, called the simplex method, is proposed to generate the uniform design over a convex polyhedron in n-dimensional Euclidean

关键词： convex polyhedron experimental design uniform design.

Diagnostics for the structure of AGNs'broad line regions with reverberation mapping data:confirmation of the two-component broad line region model

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 196-201页

作者： ZHU Ling1 & ZHANG ShuangNan2 1 Department of Physics and Tsinghua center for astrophysics,Tsinghua university,beijing 100084,china 2 Key Laboratory of Particle astrophysics,Institute of High Energy Physics,chinese academy of sciences,beijing 100049,china Department of Physics and Tsinghua center for astrophysics Tsinghua University Beijing China Key Laboratory of Particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing China

We re-examine the ten Reverberation Mapping(RM) sources with public data based on the two-component model of the Broad Line Region(BLR).In fitting their broad Hβ Mlines,six of them only need one Gaussian component,one of them has a double-peak profile,one has an irregular profile,and only two of them need two components,i.e.,a Very Broad Gaussian Component(VBGC) and an Inter-Mediate Gaussian Component(IMGC).The Gaussian components are assumed to come from two distinct regions in the two-component model;they are the Very Broad Line Region(VBLR) and the Inter-Mediate Line region(IMLR).The two sources with a two-component profile are Mrk 509 and NGC *** time lags of the two components of both sources satisfy tIMLR/tVBLR=V 2VBLR/V 2IMLR,where tIMLR and tVBLR are the lags of the two components while VIMLR and VVBLR represent the mean gas velocities of the two regions,supporting the two-component model of the BLR of Active Galactic Nuclei(AGNs).The fact that most of these ten sources only have the VBGC confirms the assumption that RM mainly measures the radius of the VBLR;consequently,the radius obtained from the R-L relationship mainly represents the radius of ***,NGC 4051,with a lag of about 5 days in the one component model,is an outlier on the R-L relationship as shown in Kaspi et al.(2005);however this problem disappears in our two-component model with lags of about 2 and 6 days for the VBGC and IMGC,respectively.

关键词： broad line region AGN Reverberation Mapping cross correlation

Observation constraints of the hard X-ray modulation telescope HXMT

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 31-35页

作者： LU Yu1,2,ZHANG WenZhao3,QU JinLu1,SONG LiMing1,GAO Jian3,ZHANG HongMei4 & OU Ge4 1 Key Laboratory of Particle astrophysics,Institute of High Energy Physics,chinese academy of sciences,beijing 100049,china 2 Graduate university of chinese academy of sciences,beijing 100049,china 3 Department of Astronomy,beijing Normal university,beijing 100875,china 4 Computing center,Institute of High Energy Physics,chinese academy of sciences,beijing 100049,china Key Laboratory of Particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing China Graduate university of chinese academy of sciences Beijing China Department of Astronomy Beijing Normal University Beijing China Computing center Institute of High Energy Physics Chinese Academy of Sciences Beijing China

The hard X-ray modulation telescope HXMT is a low orbit X-ray space telescope whose main science goals are to accomplish a hard X-ray all sky survey and to study timing and spectral characteristics of X-ray *** has three kinds of science instruments:the high energy X-ray detector(HE),the medium energy X-ray detector(ME) and the low energy X-ray detector(LE).The observation schedule of HXMT is a key to achieving the science goal of HXMT,and the analysis of the observation constraints is one of the first tasks in making the observation *** paper analyzes how the observation constraints influence the sky visibility and the visible time distribution of X-ray sources and discusses the schedule strategy with regard to the observation constraints.

关键词： HXMT observation constraints sky visibility

Design of secure operating systems with high security levels

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Science in china(Series F) 2007年第3期50卷 399-418页

作者： QING SiHan1,2 & SHEN ChangXiang3 1 Institute of Software, chinese academy of sciences, beijing 100080, china 2 School of Software and Microelectronics, peking university, beijing 102600, china 3 Institute of Computing Technology, Navy, beijing 100841, china Institute of Software Chinese Academy of Sciences School of Software and Microelectronics Peking University Institute of Computing Technology

Numerous Internet security incidents have shown that support from secure operating systems is paramount to fighting threats posed by modern computing environments. Based on the requirements of the relevant national and international standards and criteria, in combination with our experience in the design and development of the ANSHENG v4.0 secure operating system with high security level （hereafter simply referred to as ANSHENG OS）, this paper addresses the following key issues in the design of secure operating systems with high security levels： security architecture, security policy models, and covert channel analysis. The design principles of security architecture and three basic security models： confidentiality, integrity, and privilege control models are discussed, respectively. Three novel security models and new security architecture are proposed. The prominent features of these proposals, as well as their applications to the ANSHENG OS, are elaborated. Cover channel analysis （CCA） is a well-known hard problem in the design of secure operating systems with high security levels since to date it lacks a sound theoretical basis and systematic analysis approach. In order to resolve the fundamental difficulties of CCA, we have set up a sound theoretical basis for completeness of covert channel identification and have proposed a unified framework for covert channel identification and an efficient backward tracking search method. The successful application of our new proposals to the ANSHENG OS has shown that it can help ease and speedup the entire CCA process.

关键词： secure operating systems with high security levels architecture security model covert channel analysis

Callus formation in relation to changes of the membrane Ca^(2+) in the graft unions of Ginkgo biloba L.

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chinese Science Bulletin 1998年第20期43卷 1732-1736页

作者： YANG Xiong and LI Zhengli (Lee C. L.) College of Life sciences, peking university, beijing 100871, china College of Life sciences Peking University Beijing China

The relationship between the callus formation and intracellular Ca 2+ at the early stage of development of graft unions in Ginkgo biloba L. was investigated. On the second day after grafting, part of the undamaged living cells at the graft interface of the stock and scion in the regions of the cortex and pith began to dedifferentiate or divide. 8 d after grafting, a great number of callus cells were produced from the cortex and phloem, while callus bridges linking the stock with scion formed between the callus cells of the graft partners from the cortex. A membrane Ca 2+ probe, chlortetracycline (CTC), was used to locate the intracellular Ca 2+ distribution and it was found that the cortical and pith parenchyma cells were the first to show remarkably increased CTC Ca 2+ fluorescence, suggesting that the cortical and other parenchyma cells play a leading role at the early stage of development of graft unions by earlier dedifferentiation and more rapid production of callus cells.

关键词： callus formation membrane Ca 2+ graft union Ginkgo biloba.