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Approximation of dense-n/2.subgraph and table compression problems

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Science China Mathematics 2005年第9期48卷 1223-1233页

作者： XU Dachuan~1 HAN Jiye~2.& DU Dongle~3.1. College of Applied Sciences,beijing {2. of Technology,beijing 10002.,China 2. Institute of Applied Mathematics,Academy of Mathematics and Systems Science,Chinese Academy of Sciences,beijing 100080,China 3. Faculty of Administration,{2. of New Brunswick,p.O.Box 4400,Fredericton,NB E3. 5A3.Canada College of Applied Sciences Beijing University of Technology Beijing 100022 China Institute of Applied Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China Faculty of Administration University of New Brunswick P.O. Box 4400 Fredericton NB E3B 5A3 Canada

We develop improved approximation algorithms for two Np-hard problems: the dense-n/2.subgraph and table *** on SDp relaxation and advanced rounding techniques,we first propose 0. 5982.and 0. 5970-approximation algorithms respec- tively for the dense-n/2.subgraph problem (DSp) and the table compression problem (TCp). Then we improve these bounds to 0. 62.3.and 0. 6708 respectively for DSp and TCp by adding triangle inequalities to strengthen the SDp *** results for TCp beat the 0. 5 bound of a simple greedy algorithm on this problem,and hence answer an open question of Anderson in an affirmative way.

关键词： dense-n/2.subgraph problem(DSp) table compression problem(TCp) SDp approximation ratio

On higher analogues of Courant algebroids

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Science China Mathematics 2011年第3期54卷 437-447页

作者： BI YanHui1 & SHENG YunHe2.3.1Department of Mathematics and lmam, {2., {2., China 2.chool of Mathematics, Jilin {3., Changchun 13.012. China 3.chool of Mathematics, Dalian {3. of Technology, Dalian 11602., China 1. Department of Mathematics and lmam Peking University Beijing 100871 China2. School of Mathematics Jilin University Changchun 130012 China3. School of Mathematics Dalian University of Technology Dalian 116024 China

In this paper, we study the algebraic properties of the higher analogues of Courant algebroid structures on the direct sum bundle TM ⊕∧nT*M for an m-dimensional manifold. As an application, we revisit Nambu-poisson structures and multisymplectic structures. We prove that the graph of an (n + 1)-vector field π is closed under the higher-order Dorfman bracket iff π is a Nambu-poisson structure. Consequently, there is an induced Leibniz algebroid structure on ∧nT*M. The graph of an (n+1)-form ω is closed under the higher-order Dorfman bracket iff ω is a premultisymplectic structure of order n, i.e., dω = 0. Furthermore, there is a Lie algebroid structure on the admissible bundle A  ∧nT*M. In particular, for a 2.plectic structure, it induces the Lie 2.algebra structure given in (Baez, Hoffnung and Rogers, 2.10).

关键词： higher analogues of Courant algebroids multisymplectic structures Nambu-poisson structures Leibniz algebroids

Size-dependent hydroxyl radicals generation induced by SiO_2.ultra-fine particles: The role of surface iron

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Science China Chemistry 2009年第7期52卷 1033-1041页

作者： SHANG Yu1, ZHU Tong1, LI Yi1,2.& ZHAO JinCai3.1 College of Environmental Sciences and Engineering, p.king university, {2., China 2.Chinese Academy of Meteorological Sciences, {2., China 3.Institute of Chemistry, Chinese Academy of Sciences, {2., China 1. College of Environmental Sciences and Engineering Peking University Beijing 100871 China 2. Chinese Academy of Meteorological Sciences Beijing 100871 China 3. Institute of Chemistry Chinese Academy of Sciences Beijing 100871 China

Oxidative stress and hydroxyl radicals (·OH) play important roles in adverse health effects caused by inhalable ambient air particles (pM10). The ultra-fine fraction of pM10 has been hypothesized as one of the critical contributors to ·OH generation. Both in vivo and in vitro studies have shown that ultra-fine particles (UFps) or nano-particles generate more ·OH than larger particles with identical mass and composition. Both the surface area and surface-adsorbed redox-active metals have been suggested as factors to determine the oxidative capacity of UFps. In this study, the ·OH-generating capability of dif-ferent sizes of SiO2.particles was investigated in order to determine which factor influences particle-induced ·OH generation. The amount of ·OH generated in both acellular and cellular systems was quantified using a capillary electrophoresis method following exposure to SiO2.particles with diameters of 14, 100, and 500 nm. The amount of ·OH was strongly dependent on particle size, and a significant enhancement was observed only with 14 nm particles. Further studies indicated a close association between ·OH and iron ion concentration (R2.= 0.812. pparticles, with their surface iron being removed, did not generate ·OH. The iron-containing leachate from these washings was able to enhance ·OH production as untreated particles did. Therefore, the presence of adsorbed iron on the surface of the SiO2.particles is presented as a possible mechanism of UpFs-induced ·OH generation. The SiO2.acted as an inert substrate, and the surface of ultra-fine SiO2.particles acted as a carrier for iron.

关键词： ultra-fine particles nano-particles ·OH oxidative stress size-effect

Quick image-processing method of UAV without control points data in earthquake disaster area

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中国有色金属学会会刊：英文版 2011年第S3期21卷 523-528页

作者： LI Chang-chun1, ZHANG Guang-sheng1, LEI Tian-jie2. 3. GONG A-du2. 3.1. School of Surveying & Land Information Engineering, Henan polytechnic {2., Jiaozuo 454000, China 2. Key Laboratory of Environmental Change and Natural Disaster, Ministry of Education, beijing Normal {2., beijing 100875, China 3. Ministry of Civil Affairs/Ministry of Education of China Academy of Disaster Reduction and Emergency Management, beijing Normal {2., beijing 100875, China [a] School of Surveying & Land Information Engineering Henan Polytechnic University Jiaozuo 454000 China [b] Key Laboratory of Environmental Change and Natural Disaster Ministry of Education Beijing Normal University Beijing 100875 China [c] Ministry of Civil Affairs/Ministry of Education of China Academy of Disaster Reduction and Emergency Management Beijing Normal University Beijing 100875 China

The methods of unmanned aerial vehicles images splicing rapidly and rectifying without control points data, only using auxiliary data recorded by unmanned aerial vehicle (UAV) system, were researched. Two algorithms were proposed, including UAV images auto- splicing rapidly after image blocking and UAV images rectifying based on pseudo center points of auxiliary data. When SIFT algorithm for UAV images splicing is applied, the accuracy is very high, but the efficiency is very low. The splicing efficiency is improved greatly based on SIFT algorithm after image blocking. The results show that rectifying accuracy is very high and has no visual dislocation when pseudo center points of auxiliary data is applied.

关键词： unmanned aerial vehicles SIFT algorithm blocking quickly splicing rectification

Variation properties of ionospheric eclipse factor and ionospheric influence factor

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progress in Natural Science:Materials International 2005年第6期15卷 573-576页

作者： ZHAO Chunmei 1,2.*, YUAN Yunbin1, OU Jikun1 and CHEN Jinping3.1. Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 43.077, China 2. Graduate School of Chinese Academy of Sciences, {2. 10003., China 3. Department of precision Instrument and Mechanology, Tsinghua university, {2. 100084, China) Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan 430077 China Graduate School of Chinese Academy of Sciences Beijing 100039 China Department of precision Instrument and Mechanology Tsinghua University Beijing 100084 China

The concepts and calculation methods of ionospheric eclipse factor (IEF) and ionospheric influence factor (IFF) are further illustrated. The temporal and spacial variation properties of IEF and IFF are studied, which shows that the properties are influenced by the geographic position and season. The possibility of improving the precision of using GpS data to determine ionospheric delay based on the above variation properties is also analysed.

关键词： GpS ionospheric eclipse factor ionospheric influence factor

Raising approximation order of refinable vector by increasing multiplicity

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Science China Mathematics 2006年第1期49卷 86-97页

作者： YANG Shouzhi & pENG Lizhong Department of Mathematics, Shantou university, Shantou 515063. China {2., School of Mathematical Sciences, {2., {3., China Department of Mathematics Shantou University Shantou 515063 China lmam School of Mathematical Sciences Peking University Beijing 100871 China

An algorithm is presented for raising an approximation order of any given orthogonal multiscaling function with the dilation factor a. Let φ(x) = [φ1(x),φ2.x),…,φr(x)]T be an orthogonal multiscaling function with the dilation factor a and the approximation order m. We can construct a new orthogonal multiscaling function φnew(x) = [ φT(x). f3.+1(x),φr+2.x),…,φr+s(x)}T with the approximation order m + L(L ∈ Z+). In other words, we raise the approximation order of multiscaling function φ(x) by increasing its multiplicity. In addition, we discuss an especial setting. That is, if given an orthogonal multiscaling function φ(x) = [φ1 (x), φ2.x), …, φr(x)]T is symmetric, then the new orthogonal multiscaling function φnew(x) not only raise the approximation order but also preserve symmetry. Finally, some examples are given.

关键词： orthogonal, multiscaling functions, approximation order, symmetry.

Metallogenic characteristics of epithermal gold deposits in Tianshan, Xinjiang, China

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Chinese Science Bulletin 1999年第S2期44卷 138-139页

作者： FENG Jianzhong~1, FU Shuixing~2. WU Dewen~3.and YANG Zian~3.1. Department of Geology, {2., beijing 100871, China 2. {2. Institute of Geology for Mineral Resources, {2. 100012. China 3. Center of Remote Sensing for Geology, CNNC, {2. 101601, China Department of Geology Peking University Beijing 100871 China beijing Institute of Geology for Mineral Resources Beijing 100012 China Center of Remote Sensing for Geology CNNC Beijing 101601 China

TIANSHAN in southern Xinjiang belongs to the paleozoic island arc system in which volcanic rocks are extensively distributed. A series of epithermal gold deposits such as the Axi, Xitan, Cuiling andShuangfengshan gold deposits have been discovered. 1 Geological settings of epithermal gold deposits in Tianshan, southern Xinjiang Tianshan in southern Xinjiang belongs to the paleozoic island arc system. To its north is the Kazakhstan plate, and to its north is the Tarim plate. From west to east, the tectonic units are characterizedby Yili island arc, southern Tianshan arc-basin, Jiaoluotage island arc and Xingxingxia island arc. TheEW-trending Tianshan ore belt is controlled by Kanggurtag geosuture. In its west part, it is controlled byShenglidaban geosuture. The linear structure is NNW-trending; from north to south, the faults

关键词： metallogenic characteristics gold deposits Tianshan Xinjiang.

Integrative inversion of land surface component temperature

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Science China Earth Sciences 2005年第11期48卷 2011-2019页

作者： FAN Wenjie1 & XU Xiru1,2.1. Institute of Remote Sensing and Geographical Information System, p.king university, beijing 100871, China 2. Center of Remote Sensing and GIS of {2. Normal {3., {2. 100875, China 1. Institute of Remote Sensing and Geographical Information System Peking University 100871 Beijing China 2. Center of Remote Sensing and GIS of beijing Normal university 100875 Beijing China

In this paper, the row winter wheat was selected as the example to study the com-ponent temperature inversion method of land surface target in detail. The result showed that the structural pattern of row crop can affect the inversion precision of component temperature evi-dently. Choosing appropriate structural pattern of row crop can improve the inversion precision significantly. The iterative method combining inverse matrix was a stable method that was fit for inversing component temperature of land surface target. The result of simulation and field ex-periment showed that the integrative method could remarkably improve the inversion accuracy of the lighted soil surface temperature and the top layer canopy temperature, and enhance inver-sion stability of components temperature. Just two parameters were sufficient for accurate at-mospheric correction of multi-angle and multi-spectral thermal infrared data: atmospheric trans-mittance and the atmospheric upwelling radiance. If the atmospheric parameters and component temperature can be inversed synchronously, the really and truly accurate atmospheric correction can be achieved. The validation using ATSRII data showed that the method was useful.

关键词： components temperature, inverse pattern, atmospheric correction

The role of aerial algae in the formation of the landscape of the Yunnan Stone Forest,Yunnan province, China

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Science China Earth Sciences 2004年第9期47卷 846-864页

作者： TIAN Youping1,3. ZHANG Jie2. SONG Linhua1 & BAO Haosheng2.1. Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, beijing 100101, China 2. Department of Geography, Nanjing {2., Nanjing 2.0093. China 3. School of Earth Sciences and Resources, China {2. of Geosciences, beijing 100083. China Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Department of Geography Nanjing University Nanjing 210093 China School of Earth Sciences and Resources China University of Geosciences Beijing 100083 China

Aerial algae on the surface of carbonate rocks at the Stone Forest, Shilin County, Yunnan province, China, and their bioerosion were investigated in the field and studied in the laboratory in detail. Through the observation, identification and statistics of more than one hun- dred algal samples and rock samples with the optical microscopes (stereomicroscope, biological microscope) and the scanning electronic microscope (SEM), the relationships between erosional forms on the surface of the Stone Forest and algae and/or algal communities and the genetic mechanism for the formation of erosional forms were analyzed. It is suggested that aerial algae play an active role in bioerosive processes that may affect the formation of karst erosional forms. These effects include both direct and indirect ones. The direct effect is the initiative control (algal shape-controlling role) of algae on the formation of karst forms of various scales, mostly mi- cro-scale (3.) and minor-scale (10-3.10-1m) erosional forms. The algal shape-controlling roles can be divided into the algal individual shape-controlling role and the algal community shape-controlling role. The former mostly controls the formation of micro-scale erosional forms, while the latter mostly controls the formation of micro-scale and smaller minor-scale erosional forms. The indirect effect refers to the promoting role of algae in the formation of karst forms, which may affect the formation of karst forms of all types and scales. The bioerosion of algae accelerates the weathering process of the whole Stone Forest karst landforms.

关键词： aerial algae, bioerosion, the Stone Forest, Yunnan province, China.