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Applications of URANS on predicting unsteady turbulent separated flows

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Acta Mechanica Sinica 2009年第3期25卷 319-324页

作者： Jinglei Xu Huiyang Ma department of physics, Graduate university of the Chinese Academy of Sciences, 100049 beijing, china department of physics Graduate University of the Chinese Academy of Sciences Beijing China

Accurate prediction of unsteady separated turbulent flows remains one of the toughest tasks and a practi cal challenge for turbulence modeling. In this paper, a 2D flow past a circular cylinder at Reynolds number 3,900 is numerically investigated by using the technique of unsteady RANS （URANS）. Some typical linear and nonlinear eddy viscosity turbulence models （LEVM and NLEVM） and a quadratic explicit algebraic stress model （EASM） are evaluated. Numerical results have shown that a high-performance cubic NLEVM, such as CLS, are superior to the others in simulating turbulent separated flows with unsteady vortex shedding.

关键词： URANS Nonlinear eddy viscosity turbulencemodel ,Separated flows Circular cylinder

Some New Results in Waring's Problem

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Acta Mathematica Sinica,English Series 1996年第3期12卷 262-267页

作者： Meng Zaizhao, department of Mathematics peking university beijing 100871 china department of Mathematics Peking University Beijing China

Let G(k) denote the smallest number s such that every sufficiently large natural number is the sum of, at most, s k-th powers of natural numbers. In this paper, we give new bounds for G(12), G(13) and G(19).

关键词： Waring’s problom Circle method Iterative method Difference

Expression of PDCD5 , a novel apoptosis related protein, in human osteoarthritic cartilage

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Acta Pharmacologica Sinica 2004年第5期25卷 143-148页

作者： Ai-xin CHENG, Si-quan LOU2, Hao-wei ZHOU, Ying WANG3, Da-long MA3department of Orthopaedic Surgery, Third Hospital, peking university, beijing 100083 3Center for Human Disease Genomics, peking university, beijing 100083, china department of Orthopaedic Surgery Third Hospital Peking University 北京 100083 Center for Human Disease Genomics Peking University 北京 100083

AIM: To investigate the expression features of PDCD5 (programmed cell death 5 protein) in osteoarthritic andnormal human cartilage, and speculate on its potential functions in the pathogenesis of osteoarthritis (OA).METHODS: Articular cartilage specimens were obtained from 30 patients with OA and 16 healthy patients at thetime of arthroplasty. Expression of PDCD5 was detected by flow cytometry, immunofluorescence, RT-PCR andimmunohistochemical analysis. RESULTS: Enhanced expression and nuclear accumulation of PDCD5 in OAchondrocytes were found. PDCD5-positive chondrocytes were mainly distributed in the superficial and deep zonesof OA tissue sections, as opposed to, in the superficial and middle regions of normal healthy tissue ***: Since apoptotic chondrocyte death occurs more frequently in OA cartilage than in normal healthycartilage and PDCD5 is an apoptosis-related protein, the different expression patterns of PDCD5 in OA cartilagefrom that in normal healthy cartilage indicate that PDCD5 is involved in the pathogenesis of OA.

关键词： apoptosis cartilage osteoarthritis PDCD5

Excessive Cu and Zn affecting on distribution of the metals and activities of glycolytic and nitrogen incorporating key enzymes in mycelia of ectomycorrhizal fungi Suillus bovinus

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Journal of Environmental Sciences 2001年第3期13卷 337-341页

作者： HUANG Yi, TAO Shu(department of Urban and Environmental Sciences, peking university, beijing 100871, china. 北京大学北京 100871

Concentration of copper and zinc in isolated Suillus bovinus mycelia, used nutrient solution and 0.5 mol/L EDTA mycelia washing solution were measured to investigate the distribution of heavy metals in mycelia growth in excess copper or zinc nutrient solution. Treated with zinc, most of added zinc maintained in used solution, and 9.8%/14.6% was in/on mycelia in treatment, and in treatment 2 was 3.9%/8.0% in/on mycelia. In the copper applications, copper stimulated in more than on mycelia, i.e., 25.9%/4.5% in/on mycelia in treatment, and 7%/18.8% in/on mycelia while most of copper retained in used nutrient solution. Certain amount of copper or zinc uptake by mycelia led to pronounced influence on glycolysis and nitrogen incorporating process of Suillus bovinus, while the tested enzymes kept constant in treatment. In crude extracts of copper treatment 2 mycelia, activities of HK, PFK and GS were inhibited and decrease to 63%, 48% and 38% and GIDH increased by 68% of the control, respectively. The behaviors of these tested enzymes toward zinc corresponded in general with that towards copper. The potential protection of Suillus bovinus for its host plant under excess copper or zinc threaten was discussed.

关键词： Suillus bovinus ectomycorrhizal fungous copper zinc glycolysis nitrogen incorporate enzymes

Some Results on Entire Functions of Finite Lower Order

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Acta Mathematica Sinica,English Series 1994年第2期10卷 168-178页

作者： Wu Shengjian department of Mathematics peking university beijing, 100871 china department of Mathematics Peking University Beijing China

Let f（z） be an entire function of order λ and of finite lower order μ. If the zeros of f（z） accumulate in the vicinity of a finite number of rays, then （a） λ is finite; （b） for every arbitrary number k1>1, there exists k2>1 such that T（k1r, f）≤k2T（r, f） for all r≥r0. Applying the above results, we prove that if f（z） is extremal for Yang’s inequality p=g/2, then （c） every deficient value of f（z） is also its asymptotic value; （d） every asymptotic value of f（z） is also its deficient value; （e） λ=μ; （f） ∑a≠∞δ5（a, f）≤1-k（μ）.

关键词： Some Results on Entire Functions of Finite Lower Order

Flux of dimethylsulfide in the Jiaozhou Bay,china

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Journal of Environmental Sciences 1997年第1期9卷 80-85页

作者： Hu Min Tang Xiaoyan Center of Environmental Sciences,peking university,beijing 100871,chinaLi Jinlong Yu Zhongju department of Technical physics,peking university,beijing 100871,china Center of Environmental Sciences Peking University Beijing 100871 China department of Technical physics Peking University Beijing 100871 China

Seasonal measurements of dimethylsulfide(DMS)in surface waters were carried out during 1993-1994 in the Jiaozhou Bay.A seasonal variation is observed for DMS concentrations in seawater,ranging from 0.6 to 8.97 nmol S/L with the highest values in spring.A factor of 4 was measured for DMS concentrations with mean concentrations of 5.85 nmol S/L or 6.58 nmol S/L in spring and 1.40nmol S/L in winter.A sea-to-air flux of DMS also showed a seasonal variation.

关键词： dimethyl sulfide flux seawater atmosphere.

On the Essential Self-Adjointness of Pseudodifferential Operators

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Acta Mathematica Sinica,English Series 1994年第1期10卷 72-79页

作者： Fan Qihong department of Mathematics peking university beijing,100871 china department of Mathematics Peking University Beijing China

In this paper we investigate the self-adjointness for a kind of pseudodifferential operators,which include the nonsemi-bounded Schr（o|¨）dinger operator,-△+v（x）,v（x）→-∞, as |x|→∞,and the relativistic correc... 详细信息

关键词： On the Essential Self-Adjointness of Pseudodifferential Operators

On the Multiplier Conjecture

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Acta Mathematica Sinica,English Series 1994年第1期10卷 49-58页

作者： Qiu Weisheng department of Mathematics peking university beijing,100871 china department of Mathematics Peking University Beijing China

The Multiplier Theorem is a celebrated theorem in the Design *** condition p>λis crucial to all known proofs of the multiplier *** in all known examples of difference sets μp is a multiplier for every prime p with（p,v）=1 and *** there is the multiplier conjecture:"The multiplier theorem holds without the assumption that p> λ."The general form of the multiplier theorem may be viewed as an attempt to partially resolve the multiplier conjecture,where the assumption"p>λ"is replaced by "n1>λ".Since then Newman（1963）,Turyn（1964）,and McFarland（1970）attempted to partially resolve the multiplier conjecture（see[7],[8],[9]）.This paper will prove the following result using the representation theory of finite groups and the algebraic number theory:Let G be an abelian group of order v,v0 be the exponent of G,and D be a（v, k,λ）-difference set in *** n=2n1, then the general form of the multiplier theorem holds without the assumption that n1>λin any of the following cases: （1）2|n1; （2）2 ×n1,and（v,7）=1; （3） 2 ×n1,7|v,and t≡1 or 2 or 4（mod 7）.

关键词： On the Multiplier Conjecture Math

On the Linear Representations of Circle Expanding Maps

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Acta Mathematica Sinica,English Series 1994年第2期10卷 202-208页

作者： Cui Guizhen department of Mathematics peking university beijing, 100871 china department of Mathematics Peking University Beijing China

In this paper, it is proved that the two real analytic expanding endomorphisms of the unit circle are equivalent if and only if they have equal eigenvalues along corresponding cycles. A sufficient and necessary condit... 详细信息

关键词： Unit Circle Linear Representation Convergence Region Riemann Mapping Band Region