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Artificial coordinating field and its application to motion planning of robots in uncertain dynamic environments

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Science China(Technological sciences) 2004年第5期47卷 577-594页

作者： JING Xingjian1, 2, WANG Yuechao1 & TAN Dalong1 1. Robotics Laboratory, Shenyang Institute of Automation, chinese academy of sciences, Shenyang 110016, China 2. graduate school, chinese academy of sciences, beijing 100039, China Correspondence should be addressed to Jing Xingjian 1. Robotics Laboratory Shenyang Institute of Automation Chinese Academy of Sciences 10016 Shenyang China 2. graduate school Chinese Academy of Sciences 10039 Beijing China

Artificial coordinating fields (ACF) are proposed to deal with the motion planning problems of mobile robots in uncertain dynamic environments. An ACF around an obstacle can generate two orthogonal force vectors to a robot: one is called the coordinating force vector which is purposively designed in this paper, and the other is the repulsive force vector which is the same as that in a conventional artificial potential field. The ACF is designed according to the updated motion purpose and the relative states of the robot with respect to its local environment, and it also satisfies the robot’s dynamic constraints. The direction of the coordinating force can be determiend on line according to an optimal evaluation function. The ACF can effectively remove the local minima, and reduce the oscillation of the planned trajectory between multiple obstacles. Only local knowledge of the environments is needed in the ACF-based motion planning. The properties of the ACF such as controllability, adaptability, safety and reachability are studied and discussed in detail in this paper. Theoretical analysis and simulations are given to illustrate our main results.

关键词： artificial coordinating fields, artificial potential fields, mobile robots, motion planning, uncertain dynamic environments.

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 sciences, Qingdao 266071, China 2. Institute of Oceanology, chinese academy of sciences, Qingdao 266071, China 3. The graduate school of the chinese academy of sciences, beijing 100039, 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 chinese academy 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, 2159 tandem repeats were found, in which there were 1714 mi- crosatellites and 445 minisatellites, accounting for 79.4% and 20.6% 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 20 most abundant repeat sequence classes were as follows: AT (557), AC (471), AG (274), AAT (92), A (56), AAG (28), ATC (27), ATAG (27), 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

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 sciences, beijing 100080, China 2. graduate school, chinese academy of sciences, beijing 100060, China 3. Tropical Marine Science Institute, National University of Singapore, Singapore 119260 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.

The relation between black hole masses and Lorentz factors of the jet components in blazars

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Research in Astronomy and Astrophysics 2009年第3期9卷 293-301页

作者： Ming Zhou1,2,3 and Xin-Wu Cao1,2 1 Shanghai Astronomical Observatory, chinese academy of sciences, Shanghai 200030, China 2 Joint Institute for Galaxy and Cosmology (JOINGC) of SHAO and USMC, Shanghai 200030, China 3 graduate school of the chinese academy of sciences, beijing 10004., China Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China Joint Institute for Galaxy and Cosmology (JOINGC) of SHAO and USMC Shanghai 200030 China graduate school of the chinese academy of sciences Beijing 100049 China

We explore the relationship between black hole mass (MBH) and the motion of the jet components for a sample of blazars. The Very Long Baseline Array (VLBA) 2 cm Survey and its continuation: Monitoring of Jets in active galactic nuclei (AGNs) with VLBA Experiments (MOJAVE) have observed 278 radio-loud AGNs, of which 146 blazars have reliable measurements of their apparent velocities of the jet components. We calculate the minimal Lorentz factors for these sources from their measured apparent velocities, and their black hole masses are estimated with their broad-line widths. A sig- nificant intrinsic correlation is found between black hole masses and the minimal Lorentz factors of the jet components. The Eddington ratio is only weakly correlated with the min- imal Lorentz factor, which may imply that the Blandford-Znajek (BZ) mechanism may dominate over the Blandford-Payne (BP) mechanism for the jet acceleration (at least) in blazars.

关键词： black hole physics — galaxies: active — galaxies: jets — galaxies: nuclei

On the local wellposedness of 3-D water wave problem with vorticity

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Science China Mathematics 2007年第8期50卷 1065-1077页

作者： Ping ZHANG~1 Zhi-fei ZHANG~2 1 academy of Mathematics and Systems Science,chinese academy of sciences,beijing 100080,China 2 school of Mathematical sciences,Peking University,beijing 100871,China academy of Mathematics Systems Science Chinese Academy of Sciences Beijing 100080 China school of Mathematical sciences Peking University Beijing 100871 China

In this article, we first present an equivalent formulation of the free boundary problem to 3-D incompressible Euler equations, then we announce our local wellposedness result concerning the free boundary problem in Sobolev space provided that there is no self-intersection point on the initial surface and under the stability assumption that $\frac{{\partial p}}{{\partial n}}(\xi )\left| {_{t = 0} } \right. \leqslant - 2c_0 < 0$ being restricted to the initial surface.

关键词： water-waves free boundary incompressible Euler equations primary 35Q35 76B03 secondary 35J67 35L80

Identification of high-lipid producers for biodiesel production from forty-three green algal isolates in China

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Progress in Natural Science:Materials International 2011年第4期21卷 269-276页

作者： An-yue LIU~(1,2),Wei CHEN~1,Ling-ling ZHENG~1,Li-rong SONG~1 1.State Key Laboratory of Freshwater Ecology and Biotechnology,Institute of Hydrobiology, chinese academy of sciences,Wuhan 430072,China 2.graduate school,chinese academy of sciences,beijing 10004.,China [a] State Key Laboratory of Freshwater Ecology and Biotechnology Institute of Hydrobiology Chinese Academy of Sciences Wuhan 430072 China [b] graduate school Chinese Academy of Sciences Beijing 100049 China

To identify some desirable algal strains for our future research and/or the production of algae-based biofuel,43 green algal strains were successfully isolated from chinese freshwaters,and then incubated in the laboratory bioreactors for the growth and oil accumulation *** a 15 d incubation experiment,the accumulations of their biomass and total lipids,together with the lipid productivities for these green algal strains were systematically investigated and *** indicated that the accumulations of biomass for the 43 algal strains ranged from 0.53 g/L to 6.07 g/L during the experiments,with the highest biomass of 6.07 g/L for green algae Scenedesmus *** lipid content for the tested algal strains varied from 20%to 51%of the dry biomass at the end of cultivation *** algae Chlorella pyrenoidosa was one of the best oil producers based on our investigations,with the total lipid content of 51%of dry *** the growth rates and the accumulations of intracellular lipids into the consideration,10 strains were considered to have significant potential for biofuel *** addition,the lipid productivities of the selected strains were further investigated.

关键词： biofuel microalgae lipid accumulation

Assessing the Carrying Capacity of Tourist Resorts: An Application of Tourists’ Spatial Behavior Simulator Based on GIS and Multi-Agent System

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Wuhan University Journal of Natural sciences 2005年第4期10卷 779-784页

作者： ZHANG Ren-jun 1,2 1. Institute of Mountain Hazards and Environment, chinese academy of sciences, Chengdu 610041, Sichuan, China 2. graduated school of the chinese academy of sciences, beijing 100039, China chinese academy of sciences Institute of Mountain Hazards and Environment Chengdu Sichuan China (GRID:grid.9227.e) (ISNI:***) graduated school of the chinese academy of sciences Beijing China (GRID:grid.9227.e) (ISNI:***)

Based on the study of visitors' individual spatial behaviors, a tourists'spatial behavior simulator (TSBS) to assess the carrying capacity of tourist resorts was developed,TSBS employs GIS (Geographic Information System) to manage the spatial data,and Multi-Agent systemto simulate the actions of individual visitors. By utilizing TSBS, visitors' travel patterns such aslocation, cost, and state can be analyzed and predicted. Based on this analysis and prediction, themodel of assessing the carrying capacity of resorts is built. Our results show that TSBS will be aneffective tool to accurately assess the carrying capacity of tourist resorts.

关键词： tourist resort carrying capacity TSBS GIS Multi-Agent simulator

A SAR sidelobe suppression algorithm based on modified spatially variant apodization

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Science China(Technological sciences) 2010年第9期53卷 2542-2551页

作者： NI Chong1,2,WANG YanFei1,XU XiangHui1,ZHOU ChangYi1 & CUI PengFei1,2 1 Institute of Electronics,chinese academy of sciences,beijing 100190,China 2 graduate University of chinese academy of sciences,beijing 100039,China 1. Institute of Electronics Chinese Academy of Sciences Beijing 100190 China2. Graduate University of Chinese Academy of Sciences Beijing 100039 China

The existing spatially variant apodizations (SVAs) either cannot depress the sidelobes effectively or reduce the energy of the *** improve this,a modified SVA (MSVA) is put forward in this paper,which expands the traditional filter from 3-taps to 5-taps and sets relevant parameters according to different sampling rates to get the excellent result that satisfies constrained optimization theory.A method for synthetic aperture radar (SAR) sidelobe control based on MSVA is presented,which applies MSVA to range compression and azimuth compression to control *** method which is available for any Nyquist sampling rate can both depress the sidelobes effectively and keep the energy of the mainlobe and the resolution of the *** method can reduce sidelobe levels more effectively than classical amplitude weighting while maintaining the image resolution,as demonstrated by the result of the experiment.

关键词： synthetic aperture radar sidelobe suppression resolution SVA

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.