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LEAST-SQUARES MIXED FINITE ELEMENT METHOD FOR SADDLE-POINT PROBLEM

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Journal of Computational Mathematics 2000年第4期18卷 353-364页

作者： Lie-heng Wang Huo-yuan Duan (LSEC, institute of Computational Mathematics and Scientific/Engineering Computing, academy of Mathematics and System sciences, chinese academy of sciences, beijing, 100080, china) 中科院计算数学与科学工程计算所科学与工程计算国家重点实验室北京 100080

In this paper, a least-squares mixed finite element method for the solution of the primal saddle-point problem is developed. It is proved that the approximate problem is consistent ellipticity in the conforming finite element spaces with only the discrete BB-condition needed for a smaller auxiliary problem. The abstract error estimate is derived. [ABSTRACT FROM AUTHOR]

关键词： least-squares method mixed finite element approximation saddle-point problem

THERMODYNAMIC STUDY OF CHROMITE CAUSTIC FUSION PROCESS

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Acta Metallurgica Sinica(English Letters) 2001年第1期14卷 47-55页

作者： S.L. Zheng and Y. Zhang (institute of Chemical Metallurgy, the chinese academy of sciences, beijing 100080, china) Inst. of Chem. Metall. Chinese Acad. of Sci. Beijing 100080 China

A new method for chromate cleaning production, named chromite caustic fusion process, is advanced by institute of Chemical Metallurgy, the chinese academy of sciences. With sodium hydroxide as reaction medium, the new process is composed of three procedures: liquid phase oxidation of chromite, metastable phase separation and carbonation ammonium transition. Generally illustrating the new process and its features, this paper mainly studies the thermodynamics of chromite oxidation. The new process has much better practical results than the conventional chromate production process in which sodium carbonate is used as reaction medium. The superiority is also shown through thermodynamic studies.

关键词： Melting Oxidation Recycling Sodium compounds Thermodynamics

Strong decays of N~*(1535) in an extended chiral quark model

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Science china(Physics,Mechanics & Astronomy) 2009年第10期52卷 1452-1457页

作者： AN ChunSheng1,2,3 & ZOU BingSong1,2,3 1 institute of High Energy Physics,chinese academy of sciences,beijing 100049,china 2 Theoretical Physics Center for Science Facilities,chinese academy of sciences,beijing 100049,china 3 Graduate University of chinese academy of sciences,beijing 100049,china institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China Theoretical Physics Center for Science Facilities Chinese Academy of Sciences Beijing 100049 China Graduate University of chinese academy of sciences Beijing 100049 China

The strong decays of the N*(1535) resonance are investigated in an extended chiral quark model by including the low-lying $ qqqq\bar q $ components in addition to the qqq component. The results show that these five-quark components in N*(1535) contribute significantly to the N*(1535) → Nπ and N*(1535) → Nη decays. The contributions to the Nη decay come from both the lowest energy and the next-tolowest energy five-quarks components, while the contributions to the Nπ decay come from only the latter one. Taking these contributions into account, the description for the strong decays of N*(1535) is improved, especially for the puzzling large ratio of the decays to Nη and Nπ.

关键词： N*(1535) strong decays five-quark components

Algebraically explicit analytical solu-tions for the unsteady non-Newtonian swirling flow in an annular pipe

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Science china(Physics,Mechanics & Astronomy) 2006年第4期49卷 396-400页

作者： CAI Ruixian1 & GOU Chenhua1,2 1. institute of Engineering Thermophysics, chinese academy of sciences, beijing 100080, china 2. Graduate School, chinese academy of sciences, beijing 100080, china 1. institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100080 China 2. Graduate School Chinese Academy of Sciences Beijing 100080 China

This paper presents two algebraically explicit analytical solutions for the incompressible unsteady rotational flow of Oldroyd-B type in an annular pipe. The first solution is derived with the common method of separation of variables. The second one is deduced with the method of separation of variables with addition developed in recent years. The first analytical solution is of clear physical meaning and both of them are fairly simple and valuable for the newly developing computational fluid dynamics. They can be used as the benchmark solutions to verify the applicability of the existing numerical computational methods and to inspire new differencing schemes, grid generation ways, etc. Moreover, a steady solution for the generalized second grade rheologic fluid flow is also presented. The correctness of these solutions can be easily proven by substituting them into the original governing equation.

关键词： analytical solution, Oldroyd-B type fluid, swirling flow, non-Newtonian.

Modeling of elastic wave propagation on a curved free surface using an improved finite-difference algorithm

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Science china(Physics,Mechanics & Astronomy) 2004年第5期47卷 633-648页

作者： WANG Xiuming1,3 & ZHANG Hailan2 1. CSIRO Petroleum, ARRC, PO BOX 1130, Technology Park, Bentley, WA 6102, Australia 2. institute of Acoustics, chinese academy of sciences, beijing 100080, china 3. Present address: institute of Acoustics, chinese academy of sciences, beijing 100080, china 1. CSIRO Petroleum ARRC Technology Park PO BOX 1130 6102 Bentley WA Australia 2. institute of Acoustics Chinese Academy of Sciences 100080 Beijing China

Based on existing direct and imaging methods of a staggered finite-difference scheme, an improved algorithm for staggered finite-difference is proposed to implement rugged topographic free boundary conditions. This method assumes that the free surface can be implemented with horizontal and vertical free surface segments and their corners; the free surface passes through the grid points of shear stress components, instead of the normal stress components. Imaging is carried out for stress components in both horizontal and vertical directions, thus increasing the accuracy. To update particle- velocities, imaging and updating are first performed in the horizontal direction, and then in the vertical direction. The numerical results for elastic flat horizontal free surface with the imaging method and those for flat free surfaces of various slope angles with the proposed method are compared, and are shown to be in good agreement. The advantage of the proposed method is that only the stresses are dealt with in implementing the free surface into the staggered algorithm, which improves computation efficiency.

关键词： elastic wave simulation, curved free surface, staggered finite-difference, algorithm stability.

ELTA-WAVE IN A SIMPLE 1-D 2 x 2 HYPERBOLIC PROBLEM

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Journal of Computational Mathematics 1996年第4期14卷 311-318页

作者： S.L. Yang(institute of Applied Mathematics, chinese academy of sciences, beijing, china) institute of Applied Mathematics Chinese Academy of Sciences Beijing China

A simple one-dimensional 2 x 2 hyperbolic system is considered in the *** model contains a linear hyperbolic equation, as well as a hyperbolic equation ofwhich the coefficients are about the solution of the linear one. The exact solution ispresented and discussed, then numerical experiments are given by TVD (or MmB)type schemes for Riemann problems. From the results, we know that the solutionsdo have δ-waves for some suitable initial data.

关键词： Zhang Figure DELTA-WAVE IN A SIMPLE 1-D 2 HYPERBOLIC PROBLEM

Central simple Poisson algebras

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Science china Mathematics 2004年第2期47卷 245-263页

作者： SU Yucai & XU XiaopingDepartment of Mathematics, Shanghai Jiaotong University, Shanghai 200030, china institute of Mathematics, academy of Mathematics and System sciences, chinese academy of sciences, beijing 100080, china 1.Department of Mathematics Shanghai Jiaotong University 200030 Shanghai China 2.Institute of Mathematics Academy of Mathematics and System Sciences Chinese Academy of Sciences 100080 Beijing China

Poisson algebras are fundamental algebraic structures in physics and symplectic geometry. However, the structure theory of Poisson algebras has not been well developed. In this paper, we determine the structure of the central simple Poisson algebras related to locally finite derivations, over an algebraically closed field of characteristic *** Lie algebra structures of these Poisson algebras are in general not finitely-graded.

关键词： Poisson algebra, locally-finite operator, derivation, finitely-graded, isomorphism class.

Finding Signals for Plant Promoters

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Genomics, Proteomics & Bioinformatics 2003年第1期1卷 68-73页

作者： Weimou Zhenginstitute of Theoretical Physics, chinese academy of sciences, beijing 100080, china beijing Genomicsinstitute, chinese academy of sciences, beijing 101300, china institute of Theoretical Physics Chinese Academy of Sciences Beijing 100080 China beijing Genomics institute Chinese Academy of Sciences Beijing 101300 China

The strongest signal of plant promoter is searched with the model of single motif with two types. It turns out that the dominant type is the TATA-box. The other type may be called TATA-less signal, and may be used in gene finders for promoter recognition. While the TATA signals are very close for the monocot and the dicot, their TATA-less signals are significantly different. A general and flexible multi-motif model is also proposed for promoter analysis based on dynamic programming. By extending the Gibbs sampler to the dynamic programming and introducing temperature, an efficient algorithm is developed for searching signals in plant promoters.

关键词： for on is as et Pro Finding Signals for Plant Promoters been of into

From quantum spectra to classical orbits: Varying rectangular billiards

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Progress in Natural Science:Materials International 2008年第8期18卷 927-930页

作者： Jun Lu * Department of Foundational Science, beijing Union University, beijing 100101, china institute of Theoretical Physics, chinese academy of sciences, beijing 100080, china Department of Foundational Science Beijing Union University Beijing 100101 China institute of Theoretical Physics Chinese Academy of Sciences Beijing 100080 China

The quantum-spectrum function is introduced by means of the eigenvalues and the eigenfunctions in the system of varying rectangular billiards. It is found that the Fourier transform of the quantum-spectrum function corresponds with the classical orbits in the system. These results give new evidence about the classical-quantum correspondence.

关键词： Quantum spectrum Classical-quantum correspondence Semiclassical physics