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Periodic Solutions of N-Species Competition System with Time Delays

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生物数学学报 1997年第1期12卷 1-7页

作者： Li Yongkun(department of mathematics,{2. university,kunming 650091.People's Republic of China) 云南大学数学系云南昆明 650091

In this Paper,we establish the existence of a positive periodic solution for and obtain sufficient conditions for the periodic solution to be globally attractive.

关键词： N-species competition system periodic solution delay system global attractivity

Finite Dimensional Behavior of Global Attractors for Weakly Damping Ginzburg-Landau Equations Coupling with BBM Equations

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Communications in Nonlinear Science and Numerical Simulation 1998年第1期3卷 10-14页

作者： Boling GUO * and Murong JIANG + *(Institute of Applied Physics and Computational mathematics,Beijing,100088,China) +(department of mathematics,yunnan university,kunming 650091.China) E mail:guobl@*** Inst. Appl. Phys. and Compl. Math. Beijing 100088 China department of mathematics Yunnan University Kunming 650091 China

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关键词： dimension attractor Ginzburg Landau equation couped BBM equationIntroduction

A predict-correct projection method for monotone variant variational inequalities

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Chinese Science Bulletin 1998年第15期43卷 1264-1267页

作者： HAN Qiaoming 1 and HE Bingsheng 2.1. Institute of Applied mathematics, Chinese Academy of Sciences, Beijing 100080, China 2. department of mathematics, Nanjing {2., Nanjing 2.0093, China Institute of Applied mathematics Chinese Academy of Sciences Beijing China department of mathematics Nanjing University Nanjing China

A predict_correct projection method is presented for solving monotone variant variational inequalities, which could exploit the advantages and overcome the difficulties of both explicit and implicit projection methods.

关键词： variant variational inequality explicit projection method implicit projection method predict_correct projection method.

Two applications of generalized Carleson measures to meromorphic Besov-type spaces

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Chinese Science Bulletin 1998年第15期43卷 1260-1264页

作者： TAN Haiou 1 and XIAO Jie 2.1. department of mathematics, Wuyi {2., Jiangmen 52.02., China 2. School of Mathematical Sciences, Peking {2., Beijing 100871, China department of mathematics Wuyi University Jiangmen China School of Mathematical Sciences Peking University Beijing China

The generalized Carleson measures are used to characterize the meromorphic Besov_type spaces and to explore some inclusions between these spaces.

关键词： generalized Carleson measures meromorphic Besov_type spaces.

Mathematical stencil and its application in finite difference approximation to the Poisson equation

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Science China mathematics 2005年第10期48卷 1421-1429页

作者： FENG Hui~1 ZHANG Baolin~(1,2. & LIU Yang~1 1. department of mathematics,Wuhan {2.,Wuhan 430072.China 2. Laboratory of Computational Physics,Institute of Applied Physics and Computational mathematics,Beijing 100088. China 1. department of mathematics Wuhan University 430072 Wuhan China 2. Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics 100088 Beijing China

The concept of mathematical stencil and the strategy of stencil elimination for solving the finite difference equation is presented, and then a new type of the iteration algorithm is established for the Poisson equation. The new algorithm has not only the obvious property of parallelism, but also faster convergence rate than that of the classical Jacobi iteration. Numerical experiments show that the time for the new algorithm is less than that of Jacobi and Gauss-Seidel methods to obtain the same precision, and the computational velocity increases obviously when the new iterative method, instead of Jacobi method, is applied to polish operation in multi-grid method, furthermore, the polynomial acceleration method is still applicable to the new iterative method.

关键词： mathematical stencil, stencil elimination, Poisson equation, finite difference, iterative algorithm,parallelism.

Online uniform machine covering with the known largest size

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Progress in Natural Science:Materials International 2007年第11期17卷 1271-1278页

作者： Cao Shunjuan1,2.and Tan Zhiyi1,3(1. department of mathematics, Zhejiang {2., Hangzhou 31002., China 2. department of mathematics, Zhejiang Forestry {2., Hangzhou 311300, China 3. State Key Laboratory of CAD & CG, Zhejiang {2., Hangzhou 31002., China) department of mathematics Zhejiang University Hangzhou 310027 China department of mathematics Zhejiang Forestry University Hangzhou 311300 China State Key Laboratory of CAD & CG Zhejiang University Hangzhou 310027 China

This paper investigates the semi-online scheduling problem with the known largest size on two uniform machines. The objective is to maximize the minimum machine completion time. Both lower bounds and algorithms are given. Algorithms are optimal for the majority values of s≥1, where s is the speed ratio of the two machines. The largest gap between the competitive ratio and the lower bound is about 0.064. Moreover, the overall competitive ratio 2.matches the overall lower bound.

关键词： scheduling and covering uniform machine design and analysis of algorithm online competitive ratio

Distribution of actinomycetes in oil contaminated ultisols of the Niger Delta(Nigeria)

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Journal of Environmental Sciences 2000年第3期12卷 296-302页

作者： J.P. Essien 1, E. D. Udosen 2.(1. department of Microbiology, university of Uyo, Nigeria 2. department of Chemistry and Biochemistry, university of Uyo,Nigeria) department of Microbiology University of Uyo Nigeria department of Chemistry and Biochemistry University of Uyo Nigeria

The distribution of actinomycetes in oil contaminated sandy loam ultisols of the Niger Delta region of Nigeria was studied to aid in understanding the effect of hydrocarbons on indigenous microbial population in tropical soils. The average total counts of actinomycetes in all the oil samples analysed was 10 3 cfu/g. Higher counts of actinomycetes were observed during the dry season than during the wet season. The counts of hydrocarbonoclastic actinomycetes correlated positively with the total count of actinomycetes. The actinomycetes were generally restricted to the top soil(0—10 cm soil depth) although a seemingly deeper(down to 40 cm soil depth) distribution was noticed in the dry season. The isolates included oil degrading species of Actinoplanes, Norcadia, Streptomyces and Streptosporangium. Their high oil utilization ability indicates their positive potential and role in the bioremediation of oil spilled soils.

关键词： actinomycetes oil contaminated ultisols

Pole assignment in descriptor periodic systems

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Science China mathematics 2005年第10期48卷 1309-1332页

作者： FAN Hung-Yuan~1 LIN Wen-Wei~1 & XU Shufang~2.1. department of mathematics,Tsing Hua {2.,Hsinchu 30043,China 2. LMAM,School of Mathematical Sciences,Peking {2.,Beijing 100871,China 1. department of mathematics Tsing Hua University 30043 Hsinchu China 2. LMAM School of Mathematical Sciences Peking University 100871 Beijing China

In this paper a pole assignment problem is considered for the descriptor linear discrete-time periodic systems, which is using the periodic proportional-derivative feedback to modify a given system such that the closed loop system has a specified selfconjugate set of eigenvalues. It is shown that the complete reachability of an open loop periodic system is equivalent to the possibility of assigning an arbitrary set of the eigenvalues to the system by choosing the suitable periodic proportional-derivative feedback.A computational approach is also proposed to solve the problem, which uses the reliable numerical techniques based on the orthogonal transformations. Numerical examples are presented to illustrate the effectiveness of the proposed approach.

关键词： descriptor linear periodic system, pole assignment, proportional and derivative feedback, numerical method, periodic Schur decomposition.

A Note on the Multifractal Decomposition of Directed Graph Self Similar Sets

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Wuhan university Journal of Natural Sciences 2004年第3期9卷 269-272页

作者： Zheng Shui-cao 1,2., Hu Di-he 1 1. School of mathematics and Statistics, Wuhan university , Wuhan 430072. Hubei, China 2. The Basic Teaching {2., Jimei university, Xiamen 36102., Fujian, China Wuhan university School of Mathematics and Statistics Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***) Jimei university The Basic Teaching Department Xiamen Fujian China (GRID:grid.411902.f) (ISNI:***) Wuhan university School of Mathematics and Statistics Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***)

We investigated the directed graph self similar sets under some weak overlapping condition. We get the multifractal decomposition formulas for these sets, i. e., dimK u a =DimK u a =f(a), wheref is the multifractal spectral function of the directed graph self similar measure, Especially, the results improve that of Edgar and Mauldin to the case which allows certain overlapping. Key words Hausdorff dimension - Hausdorff measure - multifractal decomposition CLC number O 2.1. 6 Foundation item: Supported by the National Natural Science Foundation of China (10371092. and the Foundation of Wuhan universityBiography: Zheng Shui-cao (1973-), male, Ph. D candidate, research direction: stochastic processes and random fractals.

关键词： Hausdorff dimension Hausdorff measure multifractal decomposition