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Low-frequency fluctuations in the magnetosheath: Double Star TC-1 and Cluster observations

Science China(Technological sciences) 2008年第10期51卷 1626-1638页

作者： DU Jian1,2.WANG Chi1, SONG Pu3,4 & ZHANG TieLong5 1 State key laboratory of {2. {2., Center for {2. Science and Applied Research, chinese academy of sciences, beijing 100190, China 2.Graduate School, chinese academy of sciences, beijing 100049, China 3 Earth, Environmental and Atmospheric sciences Department, University of Massachusetts, Lowell, Mas-sachusetts MA 01854, USA 4 Center for Atmospheric Research, University of Massachusetts, Lowell, Massachusetts MA 01854, USA 5 {2. Research Institute, Austrian academy of sciences, Graz A-8010, Austria State key laboratory of {2. {2. Center for Space Science and Applied Research Chinese Academy of Sciences Beijing China Graduate School Chinese Academy of Sciences Beijing China Earth Environmental and Atmospheric Sciences Department University of Massachusetts Lowell USA Center for Atmospheric Research University of Massachusetts Lowell USA space Research Institute Austrian Academy of Sciences Graz Austria

The magnetic field variations are analyzed in the range of time periods from 4 s to 2.0 s in the magnetosheath observed by the Double Star TC-1 and Cluster in 2.04. The characteristics of the magnetic field fluctuations are strongly controlled by the angle between the upstream interplanetary magnetic field (IMF) and the normal of the bow shock. Generally speaking, the magnetic field fluctuations in the quasi- parallel magnetosheath are more intense than those in the quasi-perpendicular ones. Almost purely compressional waves are found in the quasi-perpendicular magnetosheath. With the increase of the local plasma β, both the magnitude and direction of the magnetic field fluctuate more intensely. There exists an inverse correlation between the local temperature anisotropy T⊥/T|| and the plasma β.

关键词： low-frequency fluctuations magnetosheath MHD instabilities

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Development of environmental monitoring satellite systems in China

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Science China Earth sciences 2010年第S1期53卷 1-7页

作者： LI GuoPing1 & CAO ChunXiang2.1 School of Earth and space sciences,Peking University,{2. 100871,China 2.State key laboratory of Remote Sensing Science,Jointly Sponsored by the Institute of Remote Sensing Applications of chinese academy of sciences and {2. Normal University,{2. 100101,China School of Earth and space sciences Peking University Beijing China State key laboratory of Remote Sensing Science Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University Beijing China

With the increase in global environmental problems,the necessity and urgency of remote sensing technology being applied to environmental monitoring has been widely recognized around the *** has launched the environment and disaster monitoring and forecasting small satellite constellation HJ-1A/B and the FY3 atmosphere and environmental satellite,but they still cannot fully satisfy requirements for environmental *** paper summarizes the current status of satellite environmental monitoring in China and the existing problems of inadequate load design and low data utilization efficiency,and discusses the demand for environmental monitoring *** on the development of foreign satellite systems for environmental monitoring,the future development and key tasks of the environmental monitoring satellite system in China is discussed,as are some related initiatives.

关键词： environmental satellite environmental monitoring global climate change specialty load satellite system

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The solid lubricating material experiment device for Shenzhou-7 spaceship

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Science China(Technological sciences) 2010年第9期53卷 2521-2527页

作者： WANG Ke1,2.REN WeiJia1,WANG ShiDa1 & WENG LiJun3 1 academy of Opto-Electronics,chinese academy of sciences,{2.,China 2.Graduate University of chinese academy of sciences,beijing 100049,China 3 Lanzhou Institute of Chemical Physics,chinese academy of sciences,Lanzhou 730000,China academy of Opto-Electronics Chinese Academy of Sciences Beijing China Graduate University of chinese academy of sciences Beijing China Lanzhou Institute of Chemical Physics Chinese Academy of Sciences Lanzhou China

A solid lubricating material exposure experiment in space is one of the missions during the seventh manned spaceflight of China,and the {2. is to develop a device which can be fixed reliably outside of the orbital module and can be fetched conveniently by an astronaut during space *** solid lubricating material experiment device needs to be locked reliably in a vibrating and impacting environment during the launch phase,and should meet the requirement that it can be unlocked and fetched reliably by the astronaut wearing an extravehicular spacesuit via simple operations in orbit in an environment of high and low *** for the device we developed,the environmental characteristic of the mission was analyzed,the mechanical analysis and thermal analysis were carried out,and then a mechanism with functions of mechanical locking,structural self-locking and manual unlocking was *** device was verified by a sequence of experiments and was fetched by the astronaut during the flight of the Shenzhou-7 spaceship.

关键词： manned spaceflight exposure experiment mechanism unlock

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Validating global hydrological models by ground and space gravimetry

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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 {2. of dynamic geodesy, chinese academy of sciences, Wuhan 430077, China 3 Graduate University of chinese academy of sciences, beijing 100049, China Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan China key laboratory of dynamic geodesy Chinese Academy of Sciences Wuhan China Graduate University of chinese academy of sciences Beijing 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

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A comparative study on 3-D solar wind structure observed by Ulysses and MHD simulation

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Science Bulletin 2005年第7期50卷 672-678页

作者： FENG Xueshang, XIANG Changqing, ZHONG Dingkun & FAN Quanlin SIGMA weather Group, key {2. of {2. weather key Labo- ratory of Geo{2. Environment and Geodesy, Ministry of Education, Center for {2. Science and Applied Research, chinese academy of sciences, beijing 100080, China SIGMA weather Group Key Laboratory of Space Weather Beijing China key Labo-ratory of Geospace Environment and Geodesy Ministry of Education Center for Space Science and Applied Research Chinese Academy of Sciences Beijing China

During Ulysses’ first rapid pole-to-pole transit from September 1994 to June 1995, its observations showed that middle- or high-speed solar winds covered all latitudes except those between ?2.° and +2.° near the ecliptic plane, where the velocity was 300―450 km/s. At poleward 40°, however, only fast solar winds at the speed of 700―870 km/s were observed. In addition, the transitions from low-speed wind to high-speed wind or vice versa were abrupt. In this paper, the large-scale structure of solar wind observed by Ulysses near solar minimum is simulated by using the three-dimensional numerical MHD model. The model com- bines TVD Lax-Friedrich scheme and MacCormack II scheme and decomposes the calculation region into two re- gions: one from 1 to 2. Rs and the other from 18 Rs to 1 AU. Based on the observations of the solar photospheric magnetic field and an addition of the volumetric heating to MHD equations, the large-scale solar wind structure mentioned above is reproduced by using the three-dimensional MHD model and the numerical results are roughly consistent with Ulysses’ observations. Our simulation shows that the initial magnetic field topology and the addition of volume heating may govern the bimodal structure of solar wind observed by Ulysses and also demonstrates that the three-dimensional MHD numerical model used here is efficient in modeling the large-scale solar wind structure.

关键词： Ulysses observation solar wind structure numerical simulation.

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Latest progress on interactions between VLF/ELF waves and energetic electrons in the inner magnetosphere

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Science China Earth sciences 2010年第3期53卷 317-326页

作者： XIAO FuLiang1,2. ZONG QiuGang3, SU ZhenPeng4, TIAN Tian3 & ZHENG HuiNan4 1 School of Physics and Electronic sciences, Changsha University of Science and Technology, Changsha 410004, China 2.State key {2. of {2. weather, chinese academy of sciences, beijing 100190, China 3 Institute of {2. Physics and Applied Technology, Peking University, beijing 100871, China 4 CAS key Lab for Basic Plasma Science, School of Earth and {2. sciences, University of Science and Technology of China, Hefei 2.002., China School of Physics and Electronic sciences Changsha University of Science and Technology Changsha China State key laboratory of {2. {2. Chinese Academy of Sciences Beijing China Institute of space Physics and Applied Technology Peking University Beijing China CAS key Lab for Basic Plasma Science School of Earth and Space Sciences University of Science and Technology of China Hefei China

Interactions between very/extremely low frequency (VLF/ELF) waves and energetic electrons play a fundamental role in dynamics occurring in the inner magnetosphere. Here, we briefly discuss global properties of VLF/ELF waves, along with the variability of the electron radiation belts associated with wave-particle interactions and radial diffusion. We provide cases of electron loss and acceleration as a result of wave-particle interactions primarily due to such waves, and particularly some preliminary results of 3D evolution of phase space density from our currently developing 3D code. We comment on the existing mechanisms responsible for acceleration and loss, and identify several critical issues that need to be addressed. We review latest progress and suggest open questions for future investigation.

关键词： wave-particle interaction VLF/ELF waves energetic electrons acceleration and loss inner magnetosphere

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Identification of ten new Galactic HII regions

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Science China(Physics,Mechanics & Astronomy) 2010年第6期53卷 1144-1152页

作者： RUAN GuiPing 1,2.& SHI WeiBin 1,2.1 Shandong Provincial key laboratory of Optical Astronomy and Solar-Terrestrial Environment,School of {2. Science and Physics,Shandong University at Weihai,Weihai 2.42.9,China 2.key laboratory of Optical Astronomy,National Astronomical Observatories,chinese academy of sciences,beijing 100012.China Shandong Provincial key laboratory of Optical Astronomy and Solar-Terrestrial Environment School of Space Science and Physics Shandong University at Weihai Weihai China key laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing China

We discovered ten large HII regions in the Sino-German λ6 cm polarization survey of the Galactic plane. They have been identified according to their flat spectral indexes and the high ratio between the 60 μm infrared emission and the λ6 cm emission. The integrated flux densities as well as the sizes of these sources are given at 4800 MHz. Cross-identifications are made with other major radio catalogs.

关键词： radio continuum general-methods observational-HII regions

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Urban effects and summer thunderstorms in a tropical cyclone affected situation over Guangzhou city

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Science China Earth sciences 2007年第12期50卷 1867-1876页

作者： MENG WeiGuang1,3,YAN JingHua1 & HU HaiBo2.1 Institute of Tropical and Marine Meteorology,chinese Meteorological Administration(CMA),Guangzhou 510080,China 2.Institute of Urban Meteorology,CMA,beijing 100089,China 3 State {2. {2. of Severe weather,chinese academy of Meteorological sciences,beijing 100081,China Institute of Tropical and Marine Meteorology Chinese Meteorological Administration (CMA) Guangzhou China State key laboratory of Severe {2. Chinese Academy of Meteorological Sciences Beijing China Institute of Urban Meteorology CMA Beijing China

With data mainly from Guangzhou mesonet Automatic weather Stations(AWS),Guangzhou Doppler Radar and satellite TBB data,characteristics and evolution of the urban heat island(UHI) over Guang-zhou City were analyzed in a tropical cyclone affected situation for early August *** particular,two thunderstorms occurring during this period respectively at the night of 4 August and in the afternoon of 7 August were investigated to study the relationships between the development of thunderstorms and the *** showed that two thunderstorms were associated with the UHI *** induced local air convergence and initiated the thunderstorm *** cases showed a general agreement in time and {2. for the locations of maximum UHI,convergence,convection,and *** was found to be more favorable to developing in time periods and locations with stronger intensity of *** also showed that,due to the urban effects,both thunderstorms got strengthened when moving over Guangzhou City,with maximum radar echoes observed right over the urban area and precipitation located within the *** these features reveal that two thunderstorms were urban-induced storms.

关键词： summer thunderstorms, urban heat islands (UHI), urban effects, tropical cyclone

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Fuzzy dynamic characteristic model based attitude control of hypersonic vehicle in gliding phase

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Science China(Information sciences) 2011年第3期54卷 448-459页

作者： LUO Xiong 1,2.& LI Jiang 1 1 Department of Computer Science and Technology, key laboratory of Advanced Control of Iron and Steel Process (Ministry of Education), University of Science and Technology {2., {2. 100083, China 2.National laboratory of space Intelligent Control, beijing 100190, China Department of Computer Science and Technology Key Laboratory of Advanced Control of Iron and Steel Process (Ministry of Education) University of Science and Technology Beijing Beijing China National laboratory of space Intelligent Control Beijing China

The intelligent autonomous control of hypersonic vehicles has aroused great interest from the field of spacecraft. To solve the problem of longitudinal attitude control of hypersonic vehicle in gliding phase, a new intelligent controller is proposed in this paper. This new controller is based on the fuzzy dynamic characteristic modeling method. The fuzzy logic is introduced into the characteristic modeling by dividing the whole restriction range into several subspaces. Simulations show that this modification greatly improves the performance of the original method. With the same whole restriction range the fuzzy dynamic characteristic modeling decreases the time of convergence, and at the same time makes the attitude angle tracing more precise and robust. Since the sub-model is a characteristic model that has stronger adaptiveness than a fixed local model, the number of fuzzy rules is greatly reduced. Our model sharply reduces the complexity in constructing a fuzzy dynamic model. Finally, simulation results are given to show the effectiveness of the proposed approach in dealing with the attitude control problem of hypersonic vehicle in gliding phase.

关键词： hypersonic vehicle gliding attitude control fuzzy dynamic characteristic modeling

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IMPLICITIZATION USING UNIVARIATE RESULTANTS

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Journal of Systems Science & Complexity 2010年第4期23卷 804-814页

作者： Liyong SHEN Chunming YUAN School of Mathematical sciences Graduate University Chinese Academy of Sciences Beijing 100049 China key laboratory of Mathematics Mechanization Institute of Systems Science Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

Among several implicitization methods, the method based on resultant computation is a simple and direct one, but it often brings extraneous factors which are difficult to remove. This paper studies a class of rational space curves and rational surfaces by implicitization with univaxiate resultant computations. This method is more efficient than the other algorithms in finding implicit equations for this class of rational curves and surfaces.

关键词： Implicitization rational space curves rational surfaces resultants.

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