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Coacervate Structures of CdI_2 Thin Film Grown during Phase Transformation

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Journal of Materials Science & Technology 1997年第4期13卷 296-298页

作者： Xiaoyan YE and Lili CAO(dept. of chemistry, tsinghua university, beijing 100084, china)Jizhong ZHANG and Hengde LI(dept. of Materials Scieuce & Engineering, tsinghua university, beijing 100084, china) dept. of chemistry Tsinghua University Beijing 100084 China dept. of Materials Science and Engineering Tsinghua University Beijing 100084 China

The microstructure of CdI2 thin film grown during vapor-phase deposition was investigated by scanning electron microscopy (SEM). The thin film deposited on Si crystal consists of numerous sunflower-like aggregates. These aggregates display well self-assembly characteristics. The size of Sunflower-like aggregates is between 12 and 44 μm. Each sunflower-like aggregate is surrounded with many adjacent wings-'petals'. The structure of central region of the 'sunflower' is obviously difFerent from that of the 'petal'. Electron spectroscopy for chemical analysis (ESCA) was employed in determining the chemical valence of the thin film. Self-organization efFect is used to explain the coring growth process of CdI2 thin film

关键词： Thin Coacervate Structures of CdI2 Thin Film Grown during Phase Transformation

HIGH ACCUrACY NUMErICAL METHOD OF THIN-FILM PrOBLEMS IN MICrOMAGNETICS

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Journal of Computational Mathematics 2003年第1期21卷 33-40页

作者： Zhongyi Huang (Deft, of Mathematical Sciences, tsinghua university, beijing, 100084, china) dept. of Mathematical Sciences Tsinghua University 北京 100084

In this paper, a new high accuracy numerical method for the thin-film problems of micron and submicron size ferromagnetic elements is proposed. For the computation of stray field, we use the finite element method(FEM) by introducing a semi-discrete artificial boundary condition [1, 2]. In our numerical experiments about the domain patterns and their movement, we can see that the results are accordant to that of experiments and other numerical methods. Our method are very convenient to deal with arbitrary shape of thin films such as a polygon with high accuracy.

关键词： Thin-film Micromagnetics stray field Semi-discrete artificial boundary condition.

SOME PrOPErTIES OF LSQr FOr LArGE SPArSE LINEAr LEAST SQUArES PrOBLEMS

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Journal of Systems Science & Complexity 2010年第4期23卷 815-821页

作者： Zhongxiao JIA dep.r.ment of Mathematical Sciences,tsinghua university,beijing 100084,china. dep.r.ment of Mathematical Sciences Tsinghua University

It is well-known that many Krylov solvers for linear systems,eigenvalue problems,andsingular value decomposition problems have very simple and elegant formulas for residual *** not only allow us to further understand the methods theoretically but also can be usedas cheap stopping criteria without forming approximate solutions and residuals at each step beforeconvergence takes *** for large sparse linear least squares problems is based on the Lanczosbidiagonalization process and is a Krylov ***,there has not yet been an analogouslyelegant formula for residual *** paper derives such kind of *** addition,the authorgets some other properties of LSQr and its mathematically equivalent CGLS.

关键词： CGLS krylov subspace lanczos bidiagonalization least squares lsqr normal equations.

SYNTHESIS OF NOVEL SOLUBLE ArOMATIC POLYPYrOMELLITIMIDE CONTAINING OrDErED 1,2,4-TrIAZINE IN THE MAIN CHAIN

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Chinese Journal of Polymer Science 2002年第3期20卷 219-224页

作者： Xiao-bing Yi Guo-shi Wu Feng-cai Lu dep.r.ment of chemistry tsinghua university, beijing 100084 china Institute of chemistry Chinese Academy of Sciences, beijing 100080, china Tsing Hua Univ Dept Chem Beijing 100084 Peoples R China Chinese Acad Sci Inst Chem Beijing 100080 Peoples R China

A new heat-resistant, soluble polymer, poly(phenyl-1,2,4-triazine imide), has been prepared via a two-step method of polycondensation of N,N'-bis(4-benzil)pyromellitimide and terephthalamidrazone in cresol, followed by curing at higher temperature. The rigid 1,2,4-triazine group increases the solubility of the polyimide so that the polymer is soluble in cresol, N-methyl-2-pyrrolidone (NMP), trifluoroacetic acid and concentrated sulfuric acid, etc. Thermogravimetric analysis (TGA) indicates that this novel polyimide has good thermal stability with a high decomposition temperature of 447degreesC in air and of 423 degreesC in N-2, It has a tensile strength of 107.4 MI'a with an elongation at break of around 7.6%.

关键词： polyimides N,N '-bis(4-benzil)pyromellitimide rigid-rod group 1,2,4-triazine

THE NAGUMO EQUATION ON SELF-SIMILAr FrACTAL SETS

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Chinese Annals of Mathematics,Series B 2002年第4期23卷 519-530页

作者： HU JIAXINdep.r.ment of Mathematics, tsinghua university, beijing 100084, china. dep.r.ment of Mathematics Tsinghua University Beijing 100084 China

The Nagumo equation ut = △u+ bu(u-a)(1-u), t＞0is investigated with initial data and zero Neumann boundary conditions on post-critically finite (p.c.f.) self-similar fractals that have regular harmonic structures and satisfy the separation condition. Such a nonlinear diffusion equation has no travelling wave solutions because of the 'pathological' property of the fractal. However, it is shown that a global Holder continuous solution in spatial variables exists on the fractal considered. The Sobolev-type inequality plays a crucial role, which holds on such a class of p.c.f self-similar fractals. The heat kernel has an eigenfunction expansion and is well-defined due to a Weyl's formula. The large time asymptotic behavior of the solution is discussed, and the solution tends exponentially to the equilibrium state of the Nagumo equation as time tends to infinity if b is small.

关键词： Fractal set Spectral dimension Sobolev-type inequality Strong (Weak) solution

Zero-Thermal Expansion and Heat Capacity of Zirconium Pyrovanadate Doped with Zirconia and Vanadium (V) Oxide

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rare Metals 2001年第1期20卷 1-4页

作者： Xianran Xing, Zhenqi Zhu, Xinping Qiu, Guirong Liu (dept. of Physical chemistry university of Science and Technology beijing, beijing 100083, china dept. of chemistry, tsinghua university, beijing 100084, china) Univ Sci & Technol beijing Dept Phys Chem Beijing 100083 Peoples R China Tsing Hua Univ Dept Chem Beijing 100084 Peoples R China

The dominant phase ZrV2O7 material, doped with zirconia and vanadium (V) oxide, was synthesized by solid state reaction and sol-gel methods. X-ray power diffraction patterns show that it is cubic structure. Thermal mechanic analysis measurements exhibit a zero-thermal expansion of this material above 150 degreesC. Meanwhile, the heat capacity dependent on temperature, determined by differential scanning calorimetry, keeps in constant almost in the same temperature range. The relationship between unusual thermal expansion and abnormal heat capacity is discussed with Gruneisen parameter.

关键词： zero-thermal expansion of ZrV2O7 heat capacity Gruneisen parameter

TEXTUrE DETErMINATION OF THIN FILM ZrO_2 BY ELECTrON DIFFrACTION

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Acta Metallurgica Sinica(English Letters) 1993年第12期6卷 472-473页

作者： WANG Yinghua tsinghua university,beijing,china dep.r.ment of Materials Science and Engineering,tsinghua university,beijing 100084,china tsinghua Univ Beijing China

A method for semi-quantitative determination of thin film texture using electron diffrac- tion is *** texture state of a zirconia thin film with a cubic structure has been determined in this way and is presented as an... 详细信息

关键词： texture thin film electron diffraction ZrO_2

THE EXISTENCE OF J-HOLOMOrPHIC CUrVES AND APPLICATIONS TO THE WEINSTEIN CONJECTUrE

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Chinese Annals of Mathematics,Series B 1999年第4期20卷 425-434页

作者： MA rENYI(dep.r.ment of Applied Mathmatics, tsinghua university, beijing 100084, china) tsinghua Univ Dept Appl Math Beijing 100084 Peoples R China

The author first proves the existences of J-holomorphic curves in the symplectizations of Legendre fibrations and then as an application confirms the Weinstein conjectures on contact manifolds of Legendre fibrations. As a corollary a new proof on the theorem due to Hofer,Viterbo, Gluck, Ziller, Weinstein and Ljusternik-Fet Theorem is provided, which is quite different from their original proofs.

关键词： Symplectic geometry J-holomorphic curves Periodic orbit

A MESSAGE-DrIVING FOrMALISM FOr MODELING AND SIMULATION OF MULTI-AGENT SUPPLY CHAIN SYSTEMS

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Journal of Systems Science and Systems Engineering 2011年第4期20卷 385-399页

作者： Wenzhe TAN1 Yueting CHAI2 Yi LIU3 1dep.r.ment of Automation, tsinghua university, beijing, 100084, china 2dep.r.ment of Automation, tsinghua university, beijing, 100084, china 3dep.r.ment of Automation, tsinghua university, beijing, 100084, china dep.r.ment of Automation Tsinghua University Beijing China

To acquire a competitive advantage in the expanding market, manufacturing enterprises should be able to manage their supply chains as effectively as possible. It is now becoming popular to model supply chains as multi-agent systems and use discrete event simulation to learn more about their behaviors or investigate the implications of alternative configurations. In order to enhance the computational efficiency and keep the simulation credibility, this paper proposes a message-driving formalism for the simulation of multi-agent supply chain systems. Through the message-driving formalism, the problem of shared variables is addressed and the parallel operation of agents is implemented. Simulation experiments with a prototype implementation show that the message-driving formalism is able to provide credible results in significantly less simulation time.

关键词： Supply chain multi-agent system modeling and simulation parallel discrete event simulation message-driving formalism