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Complex variable method for plane elasticity of icosahedral quasicrystals and elliptic notch problem

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Science china(physics,Mechanics & Astronomy) 2008年第7期51卷 773-780页

作者： LI LianHe1,2.& FAN TianYou1 1 Department of physics, beijing {2. of Technology, beijing 100081, china 2.College of Mathematics Science, Inner Mongolia Normal University, Hohhot 01002., china Department of physics Beijing Institute of Technology Beijing China College of Mathematics Science Inner Mongolia Normal University Hohhot China

The complex variable method for the plane elasticity theory of icosahedral quasicrystals is developed. Based on the general solution obtained previously, complex representations of stress and displacement components of phonon and phason fields in the quasicrystals are given. With the help of conformal transformation, an analytic solution for the elliptic notch problem of the material is presented. The solution of the Griffith crack problem can be observed as a special case of the results. The stress intensity factor and energy release rate of the crack are also obtained.

关键词： icosahedral quasicrystals plane elasticity elliptic notch complex variable method

Fluorescence fluctuation spectroscopy and its artifacts:simulations and tests

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Science china(physics,Mechanics & Astronomy) 2005年第3期48卷 336-344页

作者： MENG Fanbo 1 , CHEN Bo 1 , LIU Guang 1 , DING Jianying 1 & MA Hui 2.1 1. Department of physics and Key Laboratory of Atomic and Molecular Nano Sciences, Ministry of Educa- tion, Tsinghua University, beijing 100084,{2. 2. Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055,{2. Department of physics and Key Laboratory of Atomic and Molecular Nano Sciences Ministry of Education Tsinghua University Beijing China Graduate School at Shenzhen Tsinghua University Shenzhen China

Fluorescence fluctuation spectroscopy (FFS) technique is capable of monitoring changes in concentration, mass, size and structure of fluorescent-labeled bio-molecules in microscopic volume and is suitable for measuring biological interactions in living cells. FFS data may be affected by many experimental factors in complicated biological systems. Using a Monte Carlo approach, we generate fluorescence fluctuation data for different experimental systems. This approach helps to separate the contributions by different experimental factors in a complicated fluorescence fluctuation spectrum. It also helps to validate new theoretical models and new fitting formulations. We describe the algorithm of the simulation program and tests on its statistical performance. The program is then used successfully to study the effects of several experimental factors on FFS detection.

关键词： fluorescence fluctuation spectroscopy, fluorescence correlation spectroscopy, Monte Carlo simulation.

THERMALLY STIMULATED SHAPE MEMORY BEHAVIOR OF POLYMERS WITH PHYSICAL CROSSLINKS

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Chinese Journal of Polymer Science 1999年第3期17卷 203-213页

作者： Mao Xu Feng-kui Li Polymer physics Laboratory, institute of Chemistry, Chinese Academy of Sciences,{2., china 中科院化学所高分子物理及化学国家重点实验室北京 100080 中科院化学所高分子物理及化学国家重点实验室北京

The shape memory effect of polymers was investigated for the purpose of improving the processing conditions of their preparation and broadening the list of polymers for shape memory applications. Emphasis was put on the possibility of using polymers with physical crosslinks as shape memory materials and their structure-function relationships. Segmented block polyurethanes and polyethylene/nylon 6 graft copolymers were used as examples of polymers with physical crosslinks. It was found that these copolymers can really be used as thermally stimulated shape memory materials with large recoverable strain and high final recovery rate. The main advantage of using copolymers is their improved processing conditions as compared with polymers with chemical crosslinks. As only physical crosslinks are introduced, all conventional processing techniques for thermal plastics can be used, and the materials become easily reusable. The results indicate that the high crystallinity of these copolymers at room temperature and the formation of stable physical crosslinks are the two prerequisites for these polymers to exhibit shape memory effect. The successful use of block and graft copolymers imply the possibility of using polymers of various structure and properties as shape memory materials.

关键词： shape memory effect segmented polyurethanes polyethylene nylon graft copolymers

The refined theory of deep rectangular beams based on general solutions of elasticity

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Science china(physics,Mechanics & Astronomy) 2006年第3期49卷 291-303页

作者： GAO Yang1 & WANG Minzhong2.1. College of Science, china Agricultural University, beijing 100083, china 2. State Key Laboratory for Turbulence and Complex Systems and Department of Mechanics and Engi- neering Science, Peking University, beijing 100871, china College of Science China Agricultural University Beijing China State Key Laboratory for Turbulence and Complex Systems and Department of Mechanics and Engineering Science Peking University Beijing China

The problem of deducing one-dimensional theory from two-dimensional the- ory for a homogeneous isotropic beam is investigated. Based on elasticity theory, the re- fined theory of rectangular beams is derived by using Papkovich-Neuber solution and Lur’e method without ad hoc assumptions. It is shown that the displacements and stresses of the beam can be represented by the angle of rotation and the deflection of the neutral surface. Based on the refined beam theory, the exact equations for the beam without transverse surface loadings are derived and consist of two governing differential equations: the fourth-order equation and the transcendental equation. The approximate equations for the beam under transverse loadings are derived directly from the refined beam theory and are almost the same as the governing equations of Timoshenko beam theory. In two ex- amples, it is shown that the new theory provides better results than Levinson’s beam the- ory when compared with those obtained from the linear theory of elasticity.

关键词： deep rectangular beams,the refined theory,Papkovich-Neuber solution,Lur'e method,governing equation

Experiments in numerical modelling of the Pacific sea surface temperature anomalies

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Acta Oceanologica Sinica 1992年第4期11卷 509-524页

作者： Zhang Ronghua and Wang Wanqiu institute of Atmospheric physics, Academia Sinica,{2., china institute of Atmospheric physics Academia Sinica Beijing 100080 China China

By using the atmosphere-ocean coupled model (CGCM) which is composed of a 2.level global atmospheric general circulation model and a 4-layer Pacific oceanic general circulation model developed in the institute of Atmospheric physics of Chinese Academy of Sciences, and two model climatological fields got from the two independent models' numerical integrations respectively, the Pacific sea surface temperature anomalies (SSTA) from 1988 to 1989 are simulated in this paper with observed atmospheric general circulation data and sea surface temperature fields as initial conditions and monthly coupling scheme. In order to remove systematic biases of the model climatological fields, interaction variables between atmosphere and ocean are also corrected simultaneously. The experiments show that the simulation results can be improved effectively if these interaction variables are corrected in spite of the fact that there always exist systematic biases in independent numerical simulations of atmospheric part and oceanic part within CGCM. The basic characteristics of the observed Pacific SSTA in September and October 1988 have been simulated by using the correction scheme, such as the negative SSTA domain in the whole E-quatorial Pacific east to 150°E and the positive SSTA domain in the Western Pacific, the northern subtropical Pacific and nearly the whole Southern Pacific. Further numerical simulations show that the model can simulate not only the SSTA in the Pacific and its seasonal variations but also its interannual changes (for example, La Nino event in the Equatorial Pacific terminated after May 1989) to a certain degree. Furthermore, some problems existing in experiment processes and what we shoud do in the following stage are also discussed and analysed in this paper.

关键词： Experiments in numerical modelling of the Pacific sea surface temperature anomalies SSTA

High-pressure synthesis and properties of CeO_2.ZrO_2.solid solution

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Chinese Science Bulletin 2001年第10期46卷 801-806页

作者： XU Dapeng, WANG Quanyong, LU Zhe, LIU Zhiguo, ZHANG Gongmu & SU Wenhui1. Department of physics, Jilin University, Changchun 13002. china 2. International Center for Materials physics, Chinese Academy of Sciences, Shenyang 110015, china 3. Center for Condensed Matter and Radiation physics, china Center of Advanced Science and Technology (World Laboratory), beijing 100080, china Department of physics Jilin University Changchun China International Center for Materials physics Chinese Academy of Sciences Shenyang China Center for Condensed Matter and Radiation physics China Center of Advanced Science and Technology (World Laboratory) Beijing China

Using nanoparticles of CeO2.and ZrO2.prepared by the chemical precipitation method as starting materials, the single-phase cubic Ce0.5Zr0.5O2.solid solution (c-Ce0.5Z0.5O2. has been synthesized under 3.1 GPa at 1073 K for the first time. The structure of the c-Ce0.5Zr0.5O2.has not been changed before and after annealing at 773 K for 1 h. Only an unknown EPR signal (g =1.990) has been observed in the c-Ce0.5Zr0.5O2.and not varied after annealing at 773 K for 1 h, which exhibited that there exists no Ce3+ in the c-Ce0.5Zr0.5O2.and the Ce4+ has not been reduced into Ce3+ after annealing. The transport mechanism is ionic for the c-Ce0.5Zr0.5O2. The bulk conductivity (a =1.2.10-5 S/cm at 82. K, σ=2.1 ×10-3 S/cm at 112. K) is the same as that of CeO2. but smaller than that of Y2.3-stabilized ZrO2. A marked curvature at T = 82. K has been observed in the Arrhenius plot of the bulk conductivity. The activation energy below 82. K is lower than that above 82. K, and the reason has been discussed.

关键词： CeO2.ZrO2 nanocrystalline high-pressure and -temperature solid-state reaction solid solution.

The refined theory of transversely isotropic piezoelectric rectangular beams

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Science china(physics,Mechanics & Astronomy) 2006年第4期49卷 473-486页

The problem of deducing one-dimensional theory from two-dimensional theory for a transversely isotropic piezoelectric rectangular beam is investigated. Based on the piezoelasticity theory, the refined theory of piezoelectric beams is derived by using the general solution of transversely isotropic piezoelasticity and Lur'e method without ad hoc assumptions. Based on the refined theory of piezoelectric beams, the exact equations for the beams without transverse surface loadings are derived, which consist of two governing differential equations: the fourth-order equation and the transcendental equation. The approximate equations for the beams under transverse loadings are derived directly from the refined beam theory. As a special case, the governing differential equations for transversely isotropic elastic beams are obtained from the corresponding equations of piezoelectric beams. To illustrate the application of the beam theory developed, a uniformly loaded and simply supported piezoelectric beam is examined.

关键词： rectangular beams, the refined theory, piezoelectric, transversely isotropic.

Response synchronization: New progress in brain-visual information processing

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Chinese Science Bulletin 1999年第16期44卷 1447-1458页

作者： ZHAO Songnian, XIONG Xiaoyun, YAO Guozheng and GUO Aike1. State Key Laboratory of Atmospheric Boundary Layer physics and Atmospheric Chemistry , institute of Atmospheric physics , Chinese Academy of Sciences , beijing 10002., china 2. Commission of the National Natural Science Foundation of china , beijing 100083, china 3. The Center of Information Science , Peking University, beijing 100871, china 4. Open Laboratory of Visual Information Processing , institute of Biophysics , Chinese Academy of Sciences , beijing 100101, china State Key Laboratory of Atmospheric Boundary Layer physics and Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Commission of the National Natural Science Foundation of china Beijing China The Center of Information Science Peking University Beijing China Open Laboratory of Visual Information Processing Institute of Biophysics Chinese Academy of Sciences Beijing China

Studies on brain-vision have entered a new stage, after the stimulus-induced y synchronized oscillation of neuron group activities have been discovered in cat primary visual cortex. Naturally, how to understand the visual system became a very important methodological problem. From aspects such as information processing, nonlinear dynamics and neuronal network, some primary problems in vision studies have been deeply discussed, which are

关键词： neuron group (neural population) synchro-oscillation computational theory of vision response synchroniza-tion.

Light A physics in the lepton-specific two-Higgs doublet model

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Science china(physics,Mechanics & Astronomy) 2010年第11期53卷 1981-1987页

作者： CAO JunJie 1,HENG ZhaoXia 2.3 & WAN PeiHua 1 1 College of physics & Information Engineering,Henan Normal University,Xinxiang 453007,china 2.Key Laboratory of Frontiers in Theoretical physics,institute of Theoretical physics,Chinese Academy of Sciences,beijing 100190,china 3 Kavli institute for Theoretical physics china,Chinese Academy of Sciences,beijing 100190,china Henan Normal University College of Physics &amp Information Engineering Xinxiang China (GRID:grid.462338.8) (ISNI:***) Chinese Academy of Sciences Key Laboratory of Frontiers in Theoretical Physics Institute of Theoretical Physics Beijing China (GRID:grid.9227.e) (ISNI:***) Chinese Academy of Sciences Kavli Institute for Theoretical Physics China Beijing China (GRID:grid.9227.e) (ISNI:***)

We examine various direct and indirect constraints on the lepton-specific two-Higgs doublet model and discuss its phenomenology at colliders in the allowed parameter *** constraints we consider come from the precision electroweak data,the direct search for Higgs boson,the muon anomalous magnetic moment,as well as some theoretical consistency *** find that in the allowed parameter space the CP-odd Higgs boson A is rather light (m A < 30 GeV with 95% possibility),which is composed dominantly by the leptonic Higgs and decays dominantly into τ + τ;while the SM-like Higgs boson h (responsible largely for electroweak symmetry breaking) decays dominantly in the mode h → AA → 4τ with a large decay width,which will make the Higgs discovery more difficult at the ***,this scenario predicts rare Z decays Z → AAA and Z →τ + τA with their branching ratios ranging from 10-8 to 10-and 10-5 to 10-4 respectively,which may be accessible at the GigaZ option of the ILC.

关键词： Lepton-specific two-Higgs doublt model light Higgs boson A Z decays