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CONSTRAINED QUADRILATERAL NONCONFORMING ROTATED Q1 ELEMENT

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Journal of Computational Mathematics 2005年第6期23卷 561-586页

作者： jun Hu zhong-ci Shi LSEC ICMSEC Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100080 China

In this paper, we define a new nonconforming quadrilateral finite element based on the nonconforming rotated Q1 element by enforcing a constraint on each element, which has only three degrees of freedom. We investigate the consistency, approximation, superclose property, discrete Green＇s function and superconvergence of this element. Moreover, we propose a new postprocessing technique and apply it to this element. It is proved that the postprocessed discrete solution is superconvergent under a mild assumption on the mesh.

关键词： Constrained Nonconforming Rotated Q1 element Superconvergence Postprocess

Research of Step-down Stress Accelerated Degradation Data Assessment Method of a Certain Type of Missile Tank

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Chinese Journal of Aeronautics 2012年第6期25卷 917-924页

作者： YAO jun XU Mingge zhong Weiqiang School of Reliability and System Engineering Beihang University Beijing 100191 China

The performance degradation rates of the missile tank are generally time-varying functions uneasily evaluated by general classical evaluation methods. This paper develops a segmented nonlinear accelerated degradation model （SNADM） based on the equivalent method of accumulative damage theory, which tackles the problem that product life is difficult to be determined with degradation rate being a function of the variable of time. A segmented expression of the function of population accumulative degradation is derived. And combined with nonlinear function, an accelerated degradation function, i.e., SNADM is obtained. The parameters of the SNADM are identified by numerical iteration, and the statistical function of degradation track is extrapolated. The reliability function is determined through the type of random process of the degradation distribution. Then an evaluation of product storage life is undertaken by combining the statistical function of degradation track, reliability function and threshold. An example of a missile tank undergoes a step-down stress accelerated degradation test （SDSADT）, in which the results with the SNADM and the classical method are evaluated and compared. The technology introduced is validated with the resultant coincidence of both evaluated and field storage lives.

关键词： reliability accelerated degradation model step-down stress testing life assessment cumulative damage

Drift of Spiral Waves in Complex Ginzburg-Landau Equation

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Communications in Theoretical Physics 2006年第4期45卷 647-652页

作者： YANG jun-zhong ZHANG Mei School of Science Beijing University of Posts and Telecomunications Beijing 100876 China Center for Advanced Study Tsinghua University Beljing 100084 China

The spontaneous drift of the spiral wave in a finite domain in the complex Ginzburg Landau equation is investigated numerically. By using the interactions between the spiral wave and its images, we propose a phenomeno... 详细信息

关键词： oscillatory medium spontaneous drift of spiral wave attractor

Global Existence of the Radially Symmetric Strong Solution to Navier-Stokes-Poisson Equations for Isentropic Compressible Fluids

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Acta Mathematica Sinica,English Series 2009年第10期25卷 1703-1720页

作者： jun Ping YIN zhong TAN Department of Mathematics Xiamen University Xiamen 361005 P. R. China

We prove the two existence results of the radially symmetric strong solutions to the Navier- Stokes-Poisson equations for isentropic compressible fluids. The important point in this paper is that the initial density i... 详细信息

关键词： Navier-Stokes-Poisson equations annular domain radially symmetric solution strong solution existence

Conformists and Contrarians in a Kuramoto Model with Uniformly Distributed Natural Frequencies

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Communications in Theoretical Physics 2013年第6期59卷 684-688页

作者： YUAN Di YANG jun-zhong School of Science Beijing University of Posts and Telecommunications Beijing 100876 China School of Physics and Electrical Engineering Anyang Normal University Anyang 455000 China

A generalization of the Kuramoto model in which oscillators are coupled to the mean field with random signs is investigated in this work. We focus on a situation in which the natural frequencies of oscillators follow a uniform probability density. By numerically simulating the model, we find that the model supports a modulated travelling wave state except for already reported 7r state and travelling wave state in the one with natural frequencies following Lorenztian probability density or a delta function. The dependence of the observed dynamics on the parameters of the model is explored and we find that the onset of synchronization in the model displays a non-monotonic dependence on both positive and negative coupling strength.

关键词： Kuramoto model modulated travelling wave state conformist contrarian

Generalized Synchronization in a Drive-Response System

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Communications in Theoretical Physics 2008年第2期49卷 391-395页

作者： YANG jun-zhong ZHANG Mei School of Science Beijing University of Posts and Telecommunications Beijing 100876 China Center for Advanced Study Tsinghua University Beijing 100084 China

The phenomena of GS in a drive-response system have been studied. Several kinds of GS are found： the driver-induced GS, the responser-induced GS, and the intermediate GS. The mechanism generating these types of GS is... 详细信息

关键词： generalized synchronization drive-response system

Existence of Periodic and Subharmonic Solutions for Second Order Functional Difference Equations

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Acta Mathematicae Applicatae Sinica 2010年第2期26卷 229-240页

作者： Hai-ping Shi Xue-jun zhong Basic Courses Department Guangdong Baiyun Institute Guangzhou 510450 China

In this paper, by using the critical point theory, the existence of periodic and subharmonic solutions to a class of second order functional difference equations is obtained. The main approach used in our paper is variational technique and the Saddle Point Theorem. The problem is to solve the existence of periodic and subharmonic solutions of second order forward and backward difference equations.

关键词： Periodic solutions subhaxmonic solutions functional difference equations saddle point theorem

First-principles calculation of structural and electronic properties of pyrochlore Lu_2Sn_2O_7

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Chinese Physics B 2012年第2期21卷 457-460页

作者： Chen zhong-jun Chen Tai-Hong Department of Applied Physics University of Electronic Science and Technology of ChinaChengdu 610054China College of Physical and Electronic Information China West Normal UniversityNanchong 637002China

A Density functional theory method within generalized gradient approximation has been performed to obtain the static lattice parameters, oxygen positional parameter, bond length and bond angle and electronic properties of ideal Lu2Sn207 pyrochlore. The results are in excellent agreement with available experimental measurements. Density of states （DOS） of this compound was presented and analysed. We also notice the presence of the hybridization between oxygen and Lu metal. The band structure calculations show that the compound has direct band gap of 2.67 eV at the F point in the Brillouin zone and this indicates that the material has a semi-conducting feature.

关键词： stannate pyrochlores density functional theory pseudopotential approach structureproperties

Transition to Amplitude Death in Coupled System with Small Number of Nonlinear Oscillators

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Communications in Theoretical Physics 2009年第3期51卷 460-464页

作者： CHEN Hai-Ling YANG jun-zhong School of Science Beijing University of Posts and Telecommunications Beijing 100876 China

In this work, we investigate the amplitude death in coupled system with small number of nonlinear oscillators. We show how the transitions to the partial and the complete amplitude deathes happen. We also show that th... 详细信息

关键词： coupled nonlinear oscillators amplitude death phase synchronization