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Some scaled limit theorems for an immigration super-Brownian motion

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Science china Mathematics 2008年第2期51卷 203-214页

作者： zhang mei school of mathematical sciences,beijing normal university,beijing 100875.china 1. school of mathematical sciences Beijing Normal University Beijing 100875 China

In this paper,the small time limit behaviors for an immigration super-Brownian motion are studied,where the immigration is determined by Lebesgue *** first prove a functional central limit theorem,and then study the l... 详细信息

关键词： super-Brownian motion with immigration functional central limit theorem large deviation moderate deviation 60J80 60F05

ENERGY FLOWS IN COMPLEX ECOLOGICAL SYSTEMS:A REVIEW

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Journal of Systems Science & Complexity 2009年第3期22卷 345-359页

作者： Jiang zhang Department of Systems Science,school of Management,beijing normal university,beijing 100875.china. Department of Systems Science School of Management Beijing Normal University Beijing 100875 China

Energy flow drives the complex systems to *** allometric scaling as the universalenergy flow pattern has been found in different scales of ecological *** reflects the generalpower law relationship between flow and *** underlying mechanisms of energy flow patterns areexplained as the branching transportation networks which can be regarded as the result of systematicoptimization of a biological target under *** flows in the ecological system may bemodelled by the food web model and population dynamics on the *** paper reviews thelatest progress on the energy flow patterns,explanatory models for the allometric scaling and modellingapproach of flow and network evolution dynamics in ***,the possibility of generalizingthese flow patterns,modelling approaches to other complex systems is discussed.

关键词： Allometric scaling energy flow flows in complex systems food web.

△-tame quasi-hereditary algebras

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Science china Mathematics 2007年第2期50卷 240-252页

作者： Yun-ge XU & Ying-bo zhang Faculty of Mathematics and Computer Science, Hubei university, Wuhan 430062, china school of Mathematics sciences, beijing normal university, beijing 100875. china Faculty of Mathematics and Computer Science Hubei University Wuhan China school of Mathematics sciences Beijing Normal University Beijing China

Let (K, M,H) be an upper triangular bimodule problem. Briistle and Hille showed that the opposite algebra A of the endomorphism algebra of a projective generator P of the matrices category of (K., M, H) is quasi-hereditary, and there is an equivalence between the category of△-good modules of A and Mat(K, M). In this note, based on the tame theorem for bimodule problems, we show that if the algebra A associated with an upper triangular bimodule problem is of△-tame representation type, then the category F(△) has the homogeneous property, i.e. almost all modules in F(△) are isomorphic to their Auslander-Reiten translations. Moreover, if (K, M,H)is an upper triangular bipartite bimodule problem, then A is of△-tame representation type if and only if F(△) is homogeneous.

关键词： bimodule problem quasi-hereditary algebra △-tameness homogeneity.

Moderate deviation for super-Brownian motion with immigration

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Science china Mathematics 2004年第3期47卷 440-452页

作者： zhang mei Department of Mathematics, beijing normal university, beijing 100875. china Department of Mathematics, The Central university of Finance and Economics, beijing 100081, china 1. Department of Mathematics Beijing Normal University 100875 Beijing China 2. Department of Mathematics The Central University of Finance and Economics 100081 Beijing China

We prove a moderate deviation principle for a super-Brownian motion with immigration of all dimensions, and consequently fill the gap between the central limit theorem and large deviation principle.

关键词： moderate deviation principle super-Brownian motion with immigration large deviation principle evolution equation

Characteristics of energy dissipation in hyperconcentrated flows

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International Journal of Sediment Research 2008年第4期23卷 387-397页

作者： An-ping SHU 1,Qing-quan LIU2,Yu-jun YI 3,and Zhi-dong zhang 41 Assoc.Prof.,school of Environment,Key Laboratory of Water and Sediment sciences of Ministry of Education,beijing normal university,beijing 100875.china2 Prof.,Institute of Mechanics,Chinese Academy of sciences,beijing 100080,china3 Lecturer,Dr.,school of Environment,beijing normal university,beijing 100875.china4 Graduate student,school of Environment,beijing normal university,beijing 100875.china [a]Assoc. Prof. school of Environment Key Laboratory of Water and Sediment sciences of Ministry of Education beijing normal university beijing 100875 china [b]Prof. Institute of Mechanics Chinese Academy of sciences beijing 100080 china [c]Lecturer Dr. school of Environment beijing normal university beijing 100875 china. The project is supported by the National Natural Science Foundation of china (Grant No. 10672024) [d]Graduate student school of Environment beijing normal university beijing 100875 china

An equilibrium equation for the turbulence energy in sediment-laden flows was derived on the basis of solid–liquid two-phase flow theory. The equation was simplified for two-dimensional, uniform, steady and fully developed turbulent hyperconcentrated flows. An energy efficiency coefficient of suspended-load motion was obtained from the turbulence energy equation, which is defined as the ratio of the sediment suspension energy to the turbulence energy of the sediment-laden flows. Laboratory experiments were conducted to investigate the characteristics of energy dissipation in hyperconcentrated flows. A total of 115 experimental runs were carried out, comprising 70 runs with natural sediments and 45 runs with cinder powder. Effects of sediment concentration on sediment suspension energy and flow resistance were analyzed and the relation between the energy efficiency coefficient of suspended-load motion and sediment concentration was established on the basis of experimental data. Furthermore, the characteristics of energy dissipation in hyperconcentrated flows were identified and described. It was found that the high sediment concentration does not increase the energy dissipation; on the contrary, it decreases flow resistance.

关键词： Hyperconcentrated flows Turbulence energy Efficiency coefficient Energy dissipation

Limit Theorems for Critical Galton-Watson Processes with Immigration Stopped at Zero

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Acta Mathematica Sinica,English Series 2024年第2期40卷 435-450页

作者： Dou Dou LI mei zhang Xian Yu zhang College of Statistics and Data Science Faculty of ScienceBeijing University of TechnologyBeijing 100124P.R.China Laboratory of Mathematics and Complex Systems(Ministry of Education) School of Mathematical SciencesBeijing Normal UniversityBeijing 100875P.R.China

In this paper,we consider a critical Galton-Watson branching process with immigration stopped at zero *** precise estimation on the probability generating function of the n-th population are obtained,and the tail prob... 详细信息

关键词： Branching immigration critical life period limit theorems

Geographical Agglomeration of Chinese Manufacturing Industries

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中国人口·资源与环境：英文版 2007年第2期5卷 3-11页

作者： zhang Hua 1, 2, Zheng Wei3 1. Institute of Geographical sciences and Natural Resources Research, Chinese Academy of sciences, beijing 100101, china 2. Graduate school of the Chinese Academy of sciences, beijing 100039, china 3. school of Geography, beijing normal university, beijing 100875. china Institute of Geographical sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Graduate school of the Chinese Academy of sciences Beijing 100039 China school of Geography Beijing Normal University Beijing 100875 China

Based on the plant level data from the First National Census of Basic Units, the Second National Census of Basic Units, and the First National Economic Census of china, this paper ex- amines the geographical agglomeration of Chinese manufacturing industries at a more disaggregated level both by industrial classi-fication and spatial unit analysis. Applying the agglomeration index proposed by Maurel and Sedillot, studies show that the most agglomerated industries are resource-intensive, and capital and technology intensive while industries demanding localized inputs or serving localized markets or favored by local governments are fairly dispersed. The more disaggregated industries are more spa- tially agglomerated. At the finer spatial scale, industries are more dispersed. Results indicate that within-county spillovers are stronger than nearby-county spillovers, and within-prefecture spillovers are stronger than nearby prefecture spillovers. Local- ized spillovers are still quite substantial at a range beyond that of counties. Comparing the agglomeration index of Chinese manu- facturing industries in 1996, 2001 and 2004, agglomeration seems to be a general tendency. Results also indicate that some industries have experienced remarkable changes in their levels of agglom- eration in the period 1996–2004.

关键词： industrial agglomeration manufacturing industries the MS index

Recent progress on the structure of Ser/Thr protein phosphatases

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Science china(Life sciences) 2008年第6期51卷 487-494页

作者： WANG BaiJing1,2, zhang Peng1 & WEI Qun1 1 Department of Biochemistry and Molecular Biology, beijing normal university, beijing Key Laboratory, beijing 100875. china 2 school of Life Science, Changchun normal university, Changchun 130032, china 1. Department of Biochemistry and Molecular Biology Beijing Normal University Beijing Key Laboratory Beijing 100875 China 2. school of Life Science Changchun Normal University Changchun 130032 China

PP1, PP2A and PP2B, belonging to the PPP family of Ser/Thr protein phosphatases, participate in regulating many important physiological processes, such as cell cycle control, regulation of cell growth and division regulation, etc. The sequence homology between them is relatively high, and ter- tiary structure is conserved. Because of the complexity of the structure of PP2A and the diversity of its regulatory subunits, its structure is less well known than those of PP1 and PP2B. The PP2A holoen- zyme consists of a heterodimeric core enzyme, comprising a scaffolding subunit and a catalytic sub- unit, as well as a variable regulatory subunit. In this study, the subunit compositions, similarities and differences between the Ser/Thr protein phsphatases structures are summarized.

关键词： Ser/Thr phosphatases subunit composition similarities and differences crystal structure

Robust Correlation Clustering Problem with Locally Bounded Disagreements

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Tsinghua Science and Technology 2024年第1期29卷 66-75页

作者： Sai Ji Min Li mei Liang Zhenning zhang Institute of Mathematics Hebei University of TechnologyTianjin 300401China school of Mathematics and Statistics Shandong Normal UniversityJinan 250358China College of Statistics and Data Science Beijing University of TechnologyBeijing 100124China Department of Operations Research and Information Engineering Beijing University of TechnologyBeijing 100124China

Min-max disagreements are an important generalization of the correlation clustering problem(CorCP).It can be defined as *** a marked complete graph G=(V,E),each edge in the graph is marked by a positive label"+"or a negative label"_"based on the similarity of the connected *** goal is to find a clustering C of vertices V,so as to minimize the number of disagreements at the vertex with the most ***,the disagreements are the positive cut edges and the negative non-cut edges produced by clustering *** paper considers two robust min-max disagreements:min-max disagreements with outliers and min-max disagreements with *** parameter δ∈(0,1/14),we first provide a threshold-based iterative clustering algorithm based on LP-rounding technique,which is a(1/δ,7/(1-14δ))-bi-criteria approximation algorithm for both the min-max disagreements with outliers and the min-max disagreements with outliers on one-sided complete bipartite ***,we verify that the above algorithm can achieve an approximation ratio of 21 for min-max disagreements with penalties when we set parameter δ=1/21.

关键词： min-max disagreements outliers penalties approximation algorithm LP-rounding