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A local spin evaluation into the active site models of [2.e2.] ferrodoxin [Fe_2._2.SR)_4]^(2.) (R=-H, -CH_3.

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Science china chemistry 2007年第3期50卷 327-334页

作者： WEI JiChong1,2. WANG Yan3.& JU GuanZhi2.3.1 department of {3., Hainan Normal {2., Haikou 571158, china 2.State Key Laboratory of Theoretical and Computational {3., Jilin {2., Changchun 13.02., china 3.department of {3., Nanjing {2., Nanjing 2.0093. china department of chemistry Hainan Normal University Haikou China State Key Laboratory of Theoretical and Computational chemistry Jilin University Changchun China department of chemistry Nanjing University Nanjing China

To test the feasibility of local spin theory of Davidson and Clark for ferrodoxin clusters, the models [Fe2.2.SR)4]2. (R=-H, -CH3. are chosen for evaluation. This purpose is realized by calculating the local spin expectation values , 2.>, and mA and discussing the connection between these expected values and the Heisenberg spin model (HSM) and the Noodleman broken-symmetry approach. In practical calculation, the spin-unrestricted Hartree-Fock (UHF) and spin-polarized density functional theory (DFT) are used and the calculational qualities of these two methods are also discussed. In addition, the theoretical magnetic coupling constants JAB of these models are calculated by various computational schemes for comparison with both theoretical and experimental results previously reported.

关键词： local spin iron-sulfur protein model density function theory magnetic coupling constant

Simulation study and function analysis of the dynamic aortic valve

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Progress in Natural Science:Materials International 2006年第5期16卷 512-517页

作者： XIA Dongdong and BAI Jing (department of Biomedical Engineering, tsinghua university, Beijing {2.,{3.) department of Biomedical Engineering Tsinghua University Beijing 100084 China

The dynamic aortic valve (DAV) is a new left ventricular assist device, a micro-axial blood pump implemented at the position of the aortic valve, pumping blood from the left ventricle into the aortic artery. The present dynamic aortic valve operates at 7 different rotation speeds, ranging from 3.00 r/min (speed 1) to 9000 r/min (speed 7). Because in vivo experiments need a lot of live animals and take a long period of time, modeling and simulation have been widely used to simulate and analyze hydra-dynamic property of the DAV and its assisting effects. With the measurements from the mock circulatory loop, a mathematic model of the DAV is established and embedded into the previously developed canine circulatory system. Using this model, the effect of the DAV on the failing heart at each rotation speed level is investigated. The vital cardiac variables are computed and compared with in vivo experimental results, which are in good agreement with an acceptable difference mostly 15%. The establishment of the DAV model and its simulation are useful for further improvement of the DAV device.

关键词： dynamic aortic valve mathematic model computer simulation.

THE APPROXIMATIONS OF THE EXACT BOUNDARY CONDITION AT AN ARTIFICIAL BOUNDARY FOR LINEARIZED INCOMPRESSIBLE VISCOUS FLOWS

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Journal of Computational Mathematics 1998年第3期16卷 239-256页

作者： Wei-zhu Bao (department of Applied Mathematics, tsinghua university, Beijing {2., P.R.{3.) 清华大学应用数学系北京

We consider the linearized incompressible Navier-Stokes (Oseen) equations in a flat channel. A sequence of approximations to the exact boundary condition at an artificial boundary is derived. Then the original problem is reduced to a boundary value problem in a bounded domain, which is well-posed. A finite element approximation on the bounded domain is given, furthermore the error estimate of the finite element approximation is obtained. Numerical example shows that our artificial boundary conditions are very effective.

关键词： Oseen equations artificial boundary artificial boundary condition finite element approximation error estimate

AR quivers,exceptional sequences and algorithms in derived Hall algebras

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Science china Mathematics 2010年第6期53卷 1609-1624页

作者： SHENG Jie department of Mathematical Sciences,tsinghua {2.,Beijing {3.,china department of Mathematical Sciences Tsinghua University Beijing China

Consider the canonical isomorphism between the positive part U+ of the quantum group Uq(g) and the Hall algebra H(Λ),where the semisimple Lie algebra g and the finite-dimensional hereditary algebra Λ share a Dynkin *** and Xiao have given two algorithms to decompose the root vectors into linear combinations of monomials of Chevalley generators of U+,respectively induced by the braid group action on the exceptional sequences of Λ-modules and the structure of the Auslander-Reiten quiver of Λ.In this paper,we obtain the corresponding algorithms for the derived Hall algebra DH(Λ),which was introduced by *** show that both algorithms are applicable to the lattice algebra and Heisenberg double in the sense of *** the new recursive formulae have the same flavor with the quantum Serre relations.

关键词： derived Hall algebra exceptional sequence AR quiver

Constraints on Cardassian universe from Gamma ray bursts

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Science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1720-1725页

作者： WANG TaiShan1 & LIANG Nan2.1 department of Physics & Center for Astrophysics,tsinghua {2.,Beijing 100084,china 2.department of Astronomy,Beijing Normal {2.,Beijing 100875,china department of Physics & Center for Astrophysics Tsinghua University Beijing China department of Astronomy Beijing Normal University Beijing China

Constraints on the original Cardassian model and the modified polytropic Cardassian model are examined from the recently derived 42.gamma-ray bursts(GRBs) data calibrated with the method that can avoid the circularity *** results show that GRBs can be an optional observation to constrain the Cardassian *** the GRBs data with the newly de-rived size of baryonic acoustic oscillation peak from the Sloan Digital Sky Survey(SDSS),and the position of the first acoustic peak of the Cosmic Microwave Background radiation(CMB) from Wilkinson Microwave Anisotropy Probe(WMAP),we find Ωm0=0.2.+0.02.0.02.n=0.06+0.07-0.08(1σ) for the original Cardassian model,and Ωm0=0.2.+0.2.-0.02.n=-0.09+0.2.-1.91,β=0.82.2.10-0.62.1σ) for the modified polytropic Cardassian model.

关键词： Cardassian Gamma ray burst Cosmic Microwave Background baryonic acoustic oscillation

REGULARIZATION OF SINGULAR SYSTEMS BY OUTPUTFEEDBACK

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Journal of Computational Mathematics 2000年第1期18卷 43-60页

作者： De-lin Chu Da-yong Cai(department of Mathematical Sciences, tsinghua university, Beijing {2.,{3.) 清华大学北京 100084

Presents a study which examined problem of regularization of a singular linear time-invariant system by derivative and proportional output feedback. Reduced form for the system that can be computed using orthogonal tr... 详细信息

关键词： regularization singular systems output feedback

DOPING LEVEL INCREASE OF POLY(3.METHYLTHIOPHENE)FILM DURING ELECTROCHEMICAL POLYMERIZATION PROCESS

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Chinese Journal of Polymer Science 2002年第5期20卷 425-430页

作者： Jing-kun Xu Gao-quan Shi Feng-en Chen Xiao-yin Hong department of chemistry and Bio-organic Phosphorous chemistry Laboratory{3. Beijing 100084, china department of chemistry and Bio-organic Phosphorous chemistry Laboratory Tsinghua University 北京 100084

The Raman spectra of poly(3.methylthiophene) (PMeT) films with different thicknesses, which have been electrochemically deposited on a flat stainless steel electrode surface by direct oxidation of 3.methylthiophene in boron trifluoride diethyl etherate (BFEE) at a constant applied potential of 1.3. V (versus SCE), have been investigated by excitation with a 63.-nm laser beam. The spectroscopic results demonstrated that the doping level of PMeT film was increasing during film growth. This finding was also confirmed by electrochemical examination. Moreover, the Raman bands assigned to radical cations and dications in doped PMeT films were found approximately at 142. and 1400 cm(-1), respectively. Radical cations and dications coexist on the backbone of PMeT as conductive species and their concentrations increase with the increase of doping level. Successive cyclic voltammetry was proved to be an effective approach to improving the doping level of as-grown thin compact PMeT film.

关键词： poly(3.methylthiophene) Raman spectra doping level radical cations dications

The numbers of periodic orbits hidden at fixed points of 2.dimensional holomorphic mappings

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Science china Mathematics 2010年第3期53卷 863-886页

作者： ZHANG GuangYuan department of Mathematical Sciences, tsinghua university, Beijing {2.,{3. department of Mathematical Sciences Tsinghua University Beijing China

Let △n be the ball |x| < 1 in the complex vector space C n , let f :△n→ C n be a holomorphic mapping and let M be a positive integer. Assume that the origin 0 = (0, . . . , 0) is an isolated fixed point of both f a... 详细信息

Let △n be the ball |x| 2. For a 2.× 2.matrix A that is arbitrarily given, the goal of this paper is to give a necessary and sufficient condition for A, such that O M (f, 0)≥2.for all holomorphic mappings f :△2.→ C 2.such that f(0) = 0, Df(0) = A and that the origin 0 is an isolated fixed point of f M .

关键词： complex dynamical systems periodic points fixed point indices

Arbitrarily long distance quantum communication using inspection and power insertion

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Chinese Science Bulletin 2009年第1期54卷 158-162页

作者： WANG WanYing1,2.WANG Chuan1,2.ZHANG GuangYu1,3.& LONG GuiLu1,2.1 {3. of Physics,tsinghua {2.,Beijing 100084,china 2.tsinghua National Laboratory for Information Science and Technology,tsinghua {2.,Beijing 100084,china 3.College of Applied Science,Harbin {2. of Science and Technology,Harbin 150080,china department of Physics Tsinghua University Beijing China tsinghua National Laboratory for Information Science and Technology Tsinghua University Beijing China College of Applied Science Harbin University of Science and Technology Beijing China

The biggest obstacle for long distance quantum communication is the channel loss and the channel noise on photons. In this paper,a method to solve this problem was analyzed using inspection and power insertion (IPI). It is proved that quantum communication may be established over arbitrarily long distance using this technology. The amount of resources required is a polynomial function of the dis-tance. IPI is proposed as a general technique to prolong quantum secure direct communication where secret messages are transmitted directly over a quantum channel.

关键词：长距离量子通信量子安全通信量子密匙分布噪声