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Science china(Technological Sciences) 2008年第8期51卷 1073-1086页

作者： ZHOU LiXing Department of Engineering Mechanics, tsinghua university, beijing 100084, china Department of Engineering Mechanics Tsinghua University Beijing 100084 China

The derivation and closure methods of the second-order moment (SOM) combus- tion model are proposed. The application of this model to Reynolds averaged (RANS) and large-eddy simulation (LES) of turbulent swirling diffusion combustion, jet diffusion combustion, and bluff-body stabilized premixed combustion is sum- marized. It is indicated that the SOM model is much better than the eddy-beak-up (EBU) and presumed PDF models widely used in commercial software and engi- neering. The SOM modeling results are close to those obtained using the most accurate but much more complex PDF equation model. Moreover, it can save much more computation time than the PDF equation model. Finally, the SOM model is validated by the direct numerical simulation (DNS) of turbulent reacting channel flows.

关键词： turbulent combustion second-order moment model Reynolds averaged simulation large-eddy simulation

MULTISTEP DISCRETIZATION OF INDEX 3.DAES

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Journal of Computational Mathematics 2000年第3期18卷 325-336页

作者： Yang Cao Qing-yang Li (Department of Mathematics, tsinghua university, beijing 100084, china) 清华大学北京 100084

Studies the different types of multistep discretization of index 3.differential-algebraic equations in Hessenberg form. Existense, uniqueness and influence of perturbations; Local convergence of multistep discretizati... 详细信息

关键词： multistep methods Adams method BDF DAEs Index 3

Dimensions of a class of high-dimensional homogeneous Moran sets and Moran classes

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Progress in Natural Science:Materials International 2002年第9期12卷 17-22页

作者： YAN Ping(Department of Mathematical Sciences, tsinghua university, beijing 100084, china) Tsing Hua Univ Dept Math Sci Beijing 100084 Peoples R China

A class of high-dimensional homogeneous Moran sets and Moran classes are introduced and some dimensional properties are studied. The Hausdorff dimension, modified lower box-counting dimension, lower and upper box-counting dimension, and packing dimension of high-dimensional homogeneous and partial homogeneous Cantor sets are determined. Moreover, a kind of fractal E is obtained, which is not regular but with the property Dimw(Ed) = dDimw(E), where w denotes any of the dimensions mentioned above.

关键词： Moran set Moran class homogeneous Cantor set partial homogeneous Cantor set dimension.

Γ-CONVERGENCE OF INTEGRAL FUNCTIONALS DEPENDING ON VECTOR-VALUED FUNCTIONS OVER PARABOLIC DOMAINS

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Chinese Annals of Mathematics,Series B 2000年第2期21卷 249-258页

作者： JIAN HUAIYU(Department of Mathematical Sciences, tsinghua university, beijing 100084, china.) Department of Mathematical Sciences Tsinghua University Beijing 100084 China

This paper studies Γ-convergence for a sequence of parabolic functionals, where the integrand f is nonconvex, and periodic on the first variable. The author obtains the representation formula of the Γ-limit. The results in this paper support a conclusion which relates Γ-convergence of parabolic functionals to the associated gradiend flows and confirms one of De Giorgi’s conjectures partially.

关键词： Γ-convergence Parabolic-minima Nonconvex functionals Parabolic equations

CM elliptic curves and p-adic valuations of their L-series at s=1

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Progress in Natural Science:Materials International 2002年第10期12卷 67-70页

作者： QIU Derong(center for Advanced Study, tsinghua university, beijing 100084, {3.) Tsing Hua Univ Ctr Adv Study Beijing 100084 Peoples R China

For rational integers γ and λ, consider two families of elliptic curves y2 = x3.- D1γx and y2 = x3.- 243.D2λ over fields (?) ( (-1)~1/2) and (?) ((- 3.1/2) respectively. General formulae expressed by Weierstrass (?)-functions are given for special values of Hecke L-series attached to such elliptic curves. The uniform lower bounds of 2-adic and 3.adic valuations of these values of Hecke L-series as well as global criteria for reaching these bounds are obtained. Moreover, when γ = 2 and λ = 2, 4, further results of 2-adic and 3.adic valuations are obtained for the corresponding curves in more general case of D1 and some restricted D2 respectively. These results are consistent with the predictions of the conjecture of Birch and Swinnerton-Dyer, and greatly develop and generalize some results in recent literature for more special cases.

关键词： elliptic curve L-series complex multiplication Birch and Swinnerton-Dyer conjecture.

Explicit Classification for Torsion Subgroups of Rational Points of Elliptic Curves

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Acta Mathematica Sinica,English Series 2002年第3期18卷 539-548页

作者： De Rong QIU center for Advanced Study, tsinghua university, beijing 100084. P. R. {3. Xian Ke ZHANG Department of Mathematical Sciences, tsinghua university, beijing 100084, P. R. {3. center for Advanced Study Tsinghua University Beijing P. R. China Department of Mathematical Sciences Tsinghua University Beijing P. R. China

We study the classification of elliptic curves E over the rationals Q according to the torsion subgroups E_(tors)(Q). More precisely, we classify those elliptic curves with E_(tors)(Q) being cyclic with even orders. We also give explicit formulas for generators of E_(tors)(Q). These results, together with the recent results of K. Ono for the non-cyclic E_(tors)(Q), completely solve the problem of the explicit classification and parameterization when E has a rational point of order 2.

关键词： Elliptic curve Rational point Torsion group Mordell group Parameterization

EXACT NONREFLECTING BOUNDARY CONDITIONS FOR AN ACOUSTIC PROBLEM IN THREE DIMENSIONS

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Journal of Computational Mathematics 2003年第1期21卷 15-24页

作者： Houde Han Chunxiong Zheng (Department of Mathematical Sciences, tsinghua university, beijing 100084, china) Department of Mathematical Sciences Tsinghua University 北京 100084

In this paper, nonreflecting artificial boundary conditions are considered for an acoustic problem in three dimensions. With the technique of Fourier decomposition under the orthogonal basis of spherical harmonics, three kinds of equivalent exact artificial boundary conditions are obtained on a spherical artificial boundary. A numerical test is presented to show the performance of the method.

关键词： Exterior problem Nonreflecting artificial boundary condition Acoustic equa-tion Three-dimensions.

THE GLOBAL ARTIFICIAL BOUNDARY CONDITIONS FOR NUMERICAL SIMULATIONS OF THE 3. FLOW AROUND A SUBMERGED BODY

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Journal of Computational Mathematics 2003年第4期21卷 435-450页

作者： Hou-de Han Xin Wen (Department of Mathematical Sciences, tsinghua university, beijing 100084, china) Department of Mathematical Sciences Tsinghua University Beijing 100084 China

We consider the numerical approximations of the three-dimensional steady potential flow around a body moving in a liquid of finite constant depth at constant speed and distance below a free surface in a channel. One vertical side is introduced as the upstream artificial boundary and two vertical sides are introduced as the downstream artificial boundaries. On the artificial boundaries, a sequence of high-order global artificial boundary conditions are given. Then the original problem is reduced to a problem defined on a finite computational domain, which is equivalent to a variational problem. After solving the variational problem by the finite element method, we obtain the numerical approximation of the original problem. The numerical examples show that the artificial boundary conditions given in this paper are very effective.

关键词： Ship wave Potential flow Global artificial boundary condition Finite element method.

A user-space file system for on-demand legacy desktop software

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Science china(Information Sciences) 2011年第6期54卷 1142-1150页

作者： ZHANG YouHui 1,2 , SU GeLin 1,2 & ZHENG WeiMin 1,2 1 Department of Computer Science and Technology, tsinghua university, beijing 100084, china 2 {3. National Laboratory for Information Science and Technology, tsinghua university, beijing 100084, china 1. Department of Computer Science and Technology Tsinghua University Beijing 100084 China2. Tsinghua National Laboratory for Information Science and Technology Tsinghua University Beijing 100084 China

Some user-level virtualization technologies have been used to convert legacy software (like the existing Windows desktop applications) into the on-demand software without any modification. To give the client a friendly and compatible method to access on-demand legacy software across the Internet, this paper presents a clientend file system for this usage case. It is a Windows user-space file system based on the cloud storage (where the on-demand software is stored), which converts the local file system accesses into remote visits. Quite a few optimizations are adopted and adjusted to suit the file-access-pattern of on-demand software, including the local cache, metadata/data/software prefetch and content-addressable storage (CAS), to decrease the number of remote visits and/or to overlap IO (input/output) operations with software execution. Detailed access-pattern analyses are also presented. This file system has been implemented and tests show that it is practical for much daily-used software-a local cache of limited size can provide up to 80% hit ratio and the corresponding overhead of running-time is about 3.%. Owing to this method, on any compatible and networked computer, a user can use his/her personalized software conveniently although it does not exist on the local host.

关键词： on-demand software software as a service user-space file system cloud storage

中国政治经济学年度发展报告（2023.（下）

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政治经济学评论 2024年第3期 90+207-208页

作者： center for Studies of Contemporary Political Economy,Research Institute for 21st-Century Marxism,Nankai university·university of Chinese Academy of Social Science center for Teaching and Research on Capital,Renmin university of china National Institute of Socialist Political Economy with Chinese Characteristics,Renmin university of china 南开大学·中国社会科学院大学21世纪马克思主义研究院当代政治经济学研究中心中国人民大学《资本论》教学与研究中心中国人民大学全国中国特色社会主义政治经济学研究中心

编者按2023.，高质量发展扎实推进，新质生产力加快形成，我国经济总体回升向好，圆满实现发展主要预期目标。为针对性地破解经济恢复发展中的难题，聚焦推进中国式现代化进程中的重点、难点问题，中国政治经济学界开展系统深入研究，...

编者按2023.，高质量发展扎实推进，新质生产力加快形成，我国经济总体回升向好，圆满实现发展主要预期目标。为针对性地破解经济恢复发展中的难题，聚焦推进中国式现代化进程中的重点、难点问题，中国政治经济学界开展系统深入研究，取得系列代表性成果。为准确刻画学界研究进展和轨迹，推动中国经济学理论体系的构建和完善，本刊精选议题如期奉上《中国政治经济学年度发展报告（2023.》。自2010年起，本刊连续十四年发布《中国政治经济学年度发展报告》，“年度发展报告”专栏已成为本刊标志性特色栏目。2023.报告聚焦12个专题，分为（上）（下）两篇，其中专题1—6于报告（上）篇刊登，专题7—12由报告（下）篇刊登。2023.报告（下）选题如下：

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