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A unified dynamic model for locomotion and manipulation of a snake-like robot based on differential geometry

Science china(Information sciences) 2011年第2期54卷 318-333页

作者： WANG ZhiFeng1,3, MA ShuGen1,2, LI Bin1 & WANG YueChao1 1State Key Laboratory of Robotics, Shenyang Institute of Automation, chinese academy of sciences, Shenyang 110016, china 2Department of Robotics, Ritsumeikan university, Shiga-ken 525-8577, Japan 3graduate university of chinese academy of sciences, beijing 100039, china 1. State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences Shenyang 110016 China3. Graduate University of Chinese Academy of Sciences Beijing 100039 China2. Department of Robotics Ritsumeikan University Shiga-ken 525-8577 Japan

A snake-like robot, whose body is a seried-wound articulated mechanism, can move in various environments. In addition, when one end is fixed on a base, the robot can manipulate objects. A method of dynamic modeling for locomotion and manipulation of the snake-like robot is developed in order to unify the dynamic equations of two states. The transformation from locomotion to manipulation is a mechanism reconfiguration, that is, the robot in locomotion has not a fixed base, but it in manipulation has one. First, a virtual structure method unifies the two states in mechanism (e.g., an embedding in the configuration space); second, the product-of-exponentials formula describes the kinematics; third, the dynamics of locomotion and manipulation are established in a Riemannian manifold; finally, based on the analysis of the dynamic model, the dynamics of manipulation can be directly degenerated from those of locomotion, and this degeneration relation is proved through using the Gauss equations. In the differential geometry formulation, this method realizes the unification of the dynamics of locomotion and manipulation. According to a geometrical point of view, the unified dynamic model for locomotion and manipulation is considered as a submanifold problem endowed with geometric meaning. In addition, the unified model offers an insight into the dynamics of the snake-like robot beyond the dynamic model separately established for locomotion or manipulation.

关键词： snake-like robot dynamics unified model differential geometry locomotion manipulation

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A study of spaceborne SAR raw data compression error based on a statistical model of quantization interval transfer probability

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Science china(Information sciences) 2010年第11期53卷 2352-2362页

作者： LI Xin1,2,3*, QI HaiMing1,2*, HUA Bin1,2,3, LEI Hong1 & YU WeiDong1 1Institute of Electronics, chinese academy of sciences, beijing 100190, china 2The National Key Laboratory of Microwave Imaging Technology, beijing 100190, china 3graduate university, chinese academy of sciences, beijing 100039, china 1. Institute of Electronics Chinese Academy of Sciences Beijing 100190 China2. The National Key Laboratory of Microwave Imaging Technology Beijing 100190 China3. Chinese Academy of Sciences Graduate University Beijing 100039 China

SAR raw data signal to noise ratio (SNR) after compression is of great importance since the choice of compression ratio is dependent on it during SAR system design and application analysis. The signal to quantization noise ratio (SQNR) generally used may not precisely indicate the relationship between signal and noise. Considering the thermal noise, a statistical model of quantization interval transfer probability is proposed in this paper. SNR mapping between SAR raw data before analog to digital converter (ADC) and after block adaptive quantization (BAQ) over the whole set of saturation degree is obtained using this model. When the power of echo is small with low SNR, after 1, 2, 3 or 4 bits BAQ compression, SNR has tiny difference among the four compression levels. When the power of the echo is medium with higher SNR, the SNR degradation after BAQ is about 5 dB with each bit decreasing from 4 bits. If voltage of the echo is higher than the clipping point of ADC, SNR after ADC and BAQ degrades stepwise. The higher the saturation degree of SAR raw data, the worse the SNR is. Simulated Gaussian data and real SAR raw data are used to verify the theoretical results, which are useful in the choice of BAQ compression ratio and further application analysis.

关键词： SAR raw data compression SNR saturation

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System time offset based RAIM in combined GPS/Beidou navigation system

System time offset based RAIM in combined GPS/Beidou navigat...

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第三届中国卫星导航学术年会

作者： XU LongXia1,2,3*1, LI XiaoHui1,2, XUE YanRong1,2,3, CAI ChengLin4& GUO MeiJun1,3 1National Time Service Center, chinese academy of sciences, Xi’an 710600, china 2Key Laboratory of Precision Navigation and Timing Technology, chinese academy of sciences, Xi’an 710600, china 3graduate university of chinese academy of sciences, beijing 100039, china 4Guilin university of Electronic Technology, Guilin, 541004, china

Compatibility and interoperability of GNSS （Global Navigation Satellite System） are becoming the main trend of future navigation. However, each navigation system has a time scale. When users positioning with not only one system, the time offset between them must be considered. There are several ways to acquire system time offsets. By adding unknown variables in the combined position equation to solve this variable is the commonly used way. For positioning with multi-constellations, system time offsets are some kind of burden which must be taken into account. This paper takes full use of the obtained offsets and proposes a new fault detection method for RAIM （Receiver Autonomous Integrity Monitoring）. Simulations are made to estimate the ability of this new method. This new method takes the high stability of system time offsets of GPS/Beidou system and applies it to assistant fault detection. This method has no additional requirements for navigation system and is fit for applied in receivers. It can be expected this method will be one means of RAIM for Beidou navigation system when integrated with other GNSS in future.

关键词： Compatibility and Interoperability Time Offset Receiver Autonomous Integrity Monitoring Fault Detection.

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PLS path model building:A multivariate approach to land price studies-A case study in beijing

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Progress in Natural Science:Materials International 2009年第11期19卷 1643-1649页

作者： Wenjie Wu~(a,b),Wenzhong Zhang~(a,*) a Institute of Geographic sciences and Natural Resources Research,CAS,beijing 100101,china b graduate university of chinese academy of sciences,beijing 100049,china Institute of Geographic sciences and Natural Resources Research CAS Beijing 100101 China graduate university of chinese academy of sciences Beijing 100049 China

Previous studies have revealed that statistical methods can be used to analyze land-leasing parcel ***,the conventional statistical methods used in land analysis have some limitations,especially in cases of limited observational *** this paper,with the help of geographic information system(GIS) techniques,a partial least squares(PLS) path model is applied to study the relationship between residential land prices and various determinants through a case study of beijing in *** a preliminary analysis,four latent variables are selected:accessibility of the workplace center,livability,traffic,and environment *** results show that the observation variables have a strong explanatory power for their corresponding latent variables,and the four latent variables have varying impacts on residential land *** the latent variables,accessibility to the workplace center has the strongest impact on the residential land price.

关键词： Land PLS path model GIS beijing

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Effects of cosmological constant on motion of UHECR particles

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Science china(Physics,Mechanics & Astronomy) 2005年第1期48卷 44-56页

作者： CHEN Shaoxia & CHANG Zhe Institute of High Energy Physics, chinese academy of sciences, beijing 100039, china graduate School of chinese academy of sciences, beijing 100039, china Institute of High Energy Physics Chinese Academy of Sciences Beijing 100039 China graduate School Chinese Academy of Sciences Beijing 100039 China

Recent astronomical observations manifest that about two-thirds of the whole energy in the Universe is contributed by a small positive cosmological constant A (> 0). Then, an asymptotically de Sitter spacetime is premised naturally. However, physics in the de Sitter spacetime is very different from that in the Minkowski spacetime. As the first step, a covariant formalism of the kinematics in the de Sitter spacetime is presented here. By solving exactly the equations of motion for a field, we obtain the dispersion relation of a free particle. It is noticed that the dispersion relation is dependent on the degree of freedom of angular momentum of the particle. We show the threshold anomaly of the ultra high energy cosmic ray disappears naturally in the framework of the de Sitter kinematics.

关键词： ultrahigh energy cosmic ray, cosmological constant, curved spacetime.

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Estimating possible impact of human activity on the warm season temperature in beijing since the industrial era

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chinese Science Bulletin 2010年第16期55卷 1590-1593页

作者： QIN Li1,2 & ZHOU Xin1,2 1 Institute of Geology and Geophysics,chinese academy of sciences,beijing 100029,china 2 graduate university of chinese academy of sciences,beijing 100049,china Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China graduate university of chinese academy of sciences Beijing China

Global surface temperature shows an increasing trend over the past 100 *** and natural factors have been invoked to explain this warming, but their relative contribution and the spatial variability remain *** on a 2650-year temperature record from a stalagmite near beijing, we explore the possible impacts of human activity on the warm season temperature in beijing since the industrial era using the method of singular spectrum analysis (SSA).The results suggest that the warm season temperature in beijing under the natural forcing should have an overall decreasing trend for the past 130 years (1870 to 2000 AD) with an amplitude of 0.45±0.84°C, while the instrumental record and stalagmite data show an increase of 1.08°*** imply that human activity would have caused an increase in the warm season temperature of beijing for about 1.53±0.84°C compared to its natural trends, from 1870 AD to 2000 *** results also suggest that anthropogenic forcing began to significantly influence the temperature since 1870 AD, and the effect further intensified since 1915 AD.

关键词：人类活动北京温度工业时代季节温暖估计地表气温

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Recent beijing Spectroscopy (BES) results

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Science china(Physics,Mechanics & Astronomy) 2008年第6期51卷 567-576页

作者： LI WeiGuo Institute of High Energy Physics, chinese academy of sciences, beijing 100049, china 1. Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China

Recent experimental results from beijing Spectroscopy (BES) are reviewed, including the hadron spectroscopy from J/ψ decays, and a number of new states are found or confirmed, including σ, κ, X(1835), ωφ threshold enhancement in J/ψ→γωφ, a broad resonance in J/ψ→K + K ? π 0, decay studies of ψ(2S) and χ CJ , as well as the results of ψ(3770) non-D $ \bar D $ decays. The current status of BEPCII/BESIII, the major upgrade of BEPC/BESII, is also reported.

关键词： beijing Spectroscopy hadron spectroscopy charm physics BEPCII

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Mass Spectrometric Evidence of Heparin Disaccharides for the Catalytic Characterization of A Novel Endolytic Heparinase

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Acta Biochimica et Biophysica Sinica 2004年第12期36卷 840-844页

作者： Yapeng CHAO1,3, Shaoxiang XIONG2, Xiulan CHENG1, and Shijun QIAN1* 1Institute of Microbiology, chinese academy of sciences, beijing 100080, china 2Center of Mass Spectrometry, Institute of Chemistry, chinese academy of sciences, beijing 100080, china 3graduate School of the chinese academy of sciences, beijing 100039, china Institute of Microbiology Chinese Academy of SciencesBeijing 100080 China graduate School of the chinese academy of sciencesbeijing 100039 China Center of Mass Spectrometry Institute of Chemistry Chinese Academy of SciencesBeijing 100080 China

Heparinase from different sources can eliminate heparin or/and heparan sulfate into various low-molecular weight heparins with different characteristics. Porcine intestinal mucosa heparin was de- graded into a series of oligosaccharides by a novel heparinase from the species Sphingobacterium. Disaccha- ride components from the digests were separated and purified by ultrafiltration and HPLC. Five major peaks appeared as three types according to their retention time. The mass spectrometry of peak I mainly gave the non-sulfated disaccharide with the mass of 379 Da. Peak II and III were indicated as two major monosulfated disaccharides with molecular mass of 417 and 459 Da respectively. Moreover, the peak III represented an N- acetyl disaccharide. Both peak IV and V showed the same mass of 496 Da, hinting that they were disulfate- substituted disaccharides. No trisulfate-substituted disaccharides were detected in the mixture of the heparin digest though they were abundant in the heparin structure. The results revealed that the heparinase might specifically cut the sites with low sulfated domain in heparin.

关键词： electrospray ionization-mass spectrometry heparin disaccharides heparinase high perfor- mance liquid chromatography Sphingobacterium sp.

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Recent advances in the data analysis method of functional magnetic resonance imaging and its applications in neuroimaging

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Progress in Natural Science:Materials International 2006年第8期16卷 785-795页

作者： TIAN Jie, YANG Lei and HU Jin (Institute of Automation, chinese academy of sciences, beijing 100080, china graduate School of chinese academy of sciences, beijing 100039, china) [a]chinese academy of sciences Institute of Automation Beijing China [b]graduate School of chinese academy of sciences Beijing China

Functional magnetic resonance imaging (fMRI) has opened a new area to explore the human brain. The fMRI can reveal the deep insights of spatial and temporal changes underlying a broad range of brain function, such as motor, vision, memory and emotion, all of which are helpful in the clinical investigation. In this paper, we introduce some recent-developed algorithms for fMRI signal detection such as model-driven method (general linear model, deconvolution model, non-linear model, etc. ) and data-driven method (principle component analysis, independent component analysis, self-organization mapping, clustered constrained non-negative matrix factorization, etc. ). We also propose several important applications of neuroimaging and point out their shortcomings and future perspectives.

关键词： fMR1 data analysis neuroimaging.

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Twistor bundle theory and its application

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Science china Mathematics 2004年第4期47卷 605-616页

作者： PENG Chia-Kuei & TANG ZizhouDepartment of Mathematics, graduate School of chinese academy of sciences, beijing 100039, china Department of Mathematical sciences, Tsinghua university, beijing 100084, china 1. Department of Mathematics Graduate School of Chinese Academy of Sciences 100039 Beijing China 2. Department of Mathematical sciences Tsinghua University 100084 Beijing China

Over an oriented even dimensional Riemannian manifold(M 2m ,ds2 ), in terms of the Levi-Civita connection form Ω and the canonical form Θ on the bundle of positive orthonormal frames, we give a detailed description of the twistor bundle Гm = SO(2m)/U(m)? J +(@#@ M,ds2 ) →M. The integrability on an almost complex structureJ compatible with the metric and the orientation, is shown to be equivalent to the fact that the corresponding cross section of the twistor bundle is holomorphic with respect toJ and the canonical almost complex structureJ 1 onJ +(M,ds2 ), by using moving frame theory. Moreover, for various metrics and a fixed orientation onM, a canonical bundle isomorphism is established. As a consequence, we generalize a celebrated theorem of LeBrun.

关键词： almost complex structure, integrability, twistor bundle.

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