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ON APPROXIMATION OF MAX n/2.UNCUT PROBLEM

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Journal of Systems Science & Complexity 2003年第2期16卷 260-267页

作者： XU Dachuan(institute of applied {2., {3. of {2. and Systems sciences, Chinese. {3. of sciences, beijing 100080, china) institute of applied {2. Academy of Mathematics ami Systems Sciences Chinese Aeailemy of Sciences 北京 100080

Using outward rotations, we obtain an approximation algorithm for MAXn/2.UNCUT problem, i.e., partitioning the vertices of a weighted graph into two blocks of equalcardinality such that the total weight of edges that do not cross the cut is maximized. In manyinteresting cases, the algorithm performs better than the algorithms of Ye and of Halperin andZwick. The main tool used to obtain this result is semidefinite programming.

关键词： approximation algorithm MAX n/2.UXCUT problem semidefinite programming approximation ratio

N DIMENSIONAL FINITE WAVELET FILTERS

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Journal of Computational mathematics 2003年第5期21卷 595-602页

作者： Si-long Peng (NADEC, institute of Automation, Chinese academy of {2.,{3., china) NADEC Institute of Automation Chinese Academy of Sciences 北京 100080

In this paper, a large class of n dimensional orthogonal and biorthognal wavelet filters (lowpass and highpass) are presented in explicit expression. We also characterize orthogonal filters with linear phase in this c... 详细信息

关键词： n Dimension Linear phase Wavelet filters.

Monomial Hopf algebras over fields of positive characteristic

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Science china mathematics 2006年第3期49卷 320-329页

作者： LIU Gongxiang & YE Yu institute of mathematics, {2. of mathematics and Systems Science, Chinese {2. of sciences, beijing 100080, china Department of mathematics, University of Science and Technology of china, Hefei 2.002., china institute of mathematics Academy of Mathematics Systems Science Chinese Academy of Sciences Beijing 100080 China Department of mathematics University of Science Technology of china Hefei 230026 China

In this paper, we study the structures of monomial Hopf algebras over a field of positive characteristic. A necessary and sufficient condition for the monomial coalgebra Cd(n) to admit Hopf structures is given here, and if it is the case, all graded Hopf structures on Cd(n)are completely classified. Moreover, we construct a Hopf algebras filtration on Cd(n) which will help us to discuss a conjecture posed by Andruskiewitsch and Schneider. Finally combined with a theorem by Montgomery, we give the structure theorem for all monomial Hopf algebras.

关键词： monomial coalgebra, Gaussian binomial coefficient, monomial Hopf algebra.

Global asymptotic stability of a two species competitive system with stage structure and harvesting

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Communications in Nonlinear Science and Numerical Simulation 2001年第2期6卷 81-87页

作者： Xinyu SONG and Lansun CHEN Department of mathematics, Xinyang Teachers College, Henan 464000, china {2. of mathematics, academy of mathematics and System sciences, Chinese academy of sciences, beijing 100080, china Department of mathematics Xinyang Teachers College Henan 464000 China institute of mathematics Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100080 China

The dynamics of a two species competitive system, where the species one has two stages, a immature stage and a mature stage with harvesting, and the growth of the species two is of Lotka-Volterra nature, is modelled by a system of retarded functional differential equations. We obtain the conditions for global asymptotic stability of three nonnegative equilibria and the threshold of harvesting mature population. The effect of the delay on the population at equilibrium and the optimal harvesting of mature population are also considered.

关键词： optimal harvesting stage structure competitive system global asymptotic stability.

Formation of Ultrafine Metal Particles and Metal Oxide Precursor on Anodized Al by Electrolysis Deposition

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Journal of Materials Science & Technology 2000年第1期16卷 50-54页

作者： Lingchuan LI (institute of Chemical Metallurgy, Chinese academy of {2.,{3., china) institute of Chemical Metallurgy Chinese Academy of Sciences Beijing 100080 China

Nickel was deposited by ac electrolysis deposition in the pores of the porous oxide film of Al produced by anodizing in phosphoric acid. Ultrafine rod-shaped Ni particles were formed in the pores. At the same time a film of Ni oxide precursor was developed on the surface of the porous oxide film. The Ni particles and the Ni oxide precursor were examined by SEM, TEM and X-ray diffraction. The thickness of the barrier layer of the porous oxide film was thin and it attributed to the formation of the metal particles, while the formation of the oxide precursor was associated with the surface pits which were developed in the pretreatment of Al.

关键词： Al Formation of Ultrafine Metal Particles and Metal Oxide Precursor on Anodized Al by Electrolysis Deposition

ON THE HYPER ORDER OF SOLUTIONS OF HIGHER ORDER DIFFERENTIAL EQUATIONS

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Chinese Annals of mathematics,Series B 2003年第4期24卷 501-508页

作者： CHEN ZONGXUAN Department of mathematics, Jiangxi Normai University, Nanchang 3.002., china. {2. of mathematics, academy of mathematics and System sciences, Chinese academy of sciences, beijing 100080, china. Jiangxi Normal Univ Dept Math Nanchang 330027 Peoples R China Chinese Acad Sci Acad Math & Syst Sci Inst Math Beijing 100080 Peoples R China

The author investigates the hyper order of solutions of the higher order linear equation, andimproves the results of M. Ozawa[15], G. Gundersen[6] and J. K. Langley[12..

关键词： Differential equation Entire function Hyper order

Geochemical simulation of the formation of brine and salt minerals based on Pitzer model in Caka Salt Lake

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Science china Earth sciences 2004年第8期47卷 720-726页

作者： LIU Xingqi1, CAI Keqin2.& YU Shengsong3.1. Nanjing institute of Geography and Limnology, Chinese academy of {2., Nanjing 2.0008, china 2. china University of Geo{2., beijing 100083. china 3. institute of Salt Lakes, Chinese academy of {2., Xining 810008, china 1. Nanjing institute of Geography and Limnology Chinese Academy of Sciences 210008 Nanjing China 2. china University of Geosciences 100083 Beijing China 3. institute of Salt Lakes Chinese Academy of Sciences 810008 Xining China

The geochemical simulation of the formation of brine and salt minerals based on Pitzer model was made in Caka Salt Lake. The evolution of the mixed surface-water and the mineral sequences were calculated and compared with the hydrochemical compositions of the brine and the salt minerals of the deposit in Caka Salt Lake. The results show that the formation temperature of the lake is between 0°C and 5°C, which is well identical with other studies. The mixing of salt-karst water with the surface waters, neglected by the former researchers, is very important to the formation of the lake, indicating that the initial waters resulting in the formation of the lake are multi-source. It is the first time to use Pitzer model in china for making geochemical simulation of the formation and evolution of inland salt lake and satisfactory results have been achieved.

关键词： Pitzer model,Caka Salt Lake,geochemical simulation,salt-karst water.

A global solution of the Ein-stein-Yang-Mills equation on the conformal space

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Chinese Science Bulletin 2001年第6期46卷 460-461页

作者： LU Qikenginstitute of mathematics, Chinese {2. of {3., beijing 100080, china institute of mathematics Chinese Academy of Sciences Beijing China

A global solution of the Einstein-Yang-Mills (EYM) equation on the conformal space is constructed. This solution is conformal invariant under the conformal group.

关键词： Einstein-Yang-Mills equation $12.2.-connection confor- mal space.

Relationships between tree-ring width index and NDVI of grassland in Delingha

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Chinese Science Bulletin 2006年第9期51卷 1106-1114页

作者： HE Jicheng1,3.& SHAO Xuemei1,2.. institute of Geographical sciences and Natural Resources Research, Chinese {2. of sciences, beijing 100101, china 2. institute of Tibetan Plateau Research, Chinese {2. of sciences, beijing 100085, china 3. Graduate School of Chinese {2. of sciences, beijing 10003., china institute of Geographical sciences and Natural Resources Research Chinese Academy of Sciences Beijing China Graduate School of Chinese academy of sciences Beijing China institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China

Using five well-replicated Qilian juniper (Sabina przewalskii Kom.) tree-ring width index se- ries, monthly normalized difference vegetation index (NDVI) of grassland, and climatic data from 1982.to 2.01, the relationships between tree-ring width index, NDVI of grassland, and climatic data were analyzed firstly. Then, the relationship between tree-ring width index and NDVI of grassland was explored. The re- sults showed that: (1) Temperature and precipitation in June influenced tree-ring width index and NDVI of grassland deeply in Delingha. (2. There were sig- nificant relationships between five tree-ring width index series (DLH1-DLH5) and monthly NDVI of grassland from June to September, with the most significant relationship being between tree-ring width index series and NDVI of grassland in August. (3. The PC1 (the first principal component derived from DLH1-DLH5 series) exhibited good agreement with monthly NDVI of grassland in the grass growth sea- son (from June to September) and the averaged NDVI in the growth season, which was attributed to their common responses to water-supply limit in Delingha. This study may allow an increase in studying the past dynamics of grassland in Delingha in that the variation of grassland NDVI during the last millennium has been reconstructed from PC1.

关键词：圆柏祁连山 NDVI 草原年轮宽度指数