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MD simulation of the effect of contact area and tip radius on nanoindentation

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science china(Physics,Mechanics & Astronomy) 2004年第1期47卷 101-112页

作者： CHEN Shangda1,2.& KE Fujiu1,2.1. department of Applied Physics, Beijing university of Aeronautics and Astronautics, Beijing 100083, {2. 2. State Key Laboratory of Non-linear Mechanics (LNM), Institute of Mechanics, Chinese Academy of sciences, Beijing 100080, {2. correspondence should be addressed to Chen Shangda (email: chensd@***) Received August 2., 2.03 department of Applied Physics Beijing University of Aeronautics and Astronautics Beijing China State Key Laboratory of Non-linear Mechanics (LNM) Institute of Mechanics Chinese Academy of Sciences Beijing China

Molecular dynamics simulations of nanoindentation are performed on monocrystal copper. A new contact atoms method is presented for calculating the contact area. Compared with conventional methods, this method can provide the contact area more accurately not only for sink-in but also for pile-up situation. The effect of tip radius on indentation is investigated too. The results indicate that the measured hardness of the material will become higher as the tip radius increases.

关键词： nanoindentation, molecular dynamics, contact area, zero point of penetration depth, nano- hardness.

A new method for adaptive color image filtering

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Chinese science Bulletin 2000年第13期45卷 1230-1235页

作者： jiANG Gangyi, YU Mei & YU Bokang1. department, of Information & Electronic Engineering, Hang/hou university of Commerce, Hangzhou 310035, {2. 2. department, of Electronic Engineering, Hangzhou institute of Electronics Engineering, Hangzhou 310037, {2. 3. State Key Laboratory on Machine Perception, Peking university, Beijing 100871, {2. correspondence should be addressed to Yu Mei department of Information & Electronic Engineering Hangzhou University of Commerce Hangzhou China State Key Laboratory on Machine Perception Peking University Beijing China department of Electronic Engineering Hangzhou Institute of Electronics Engineering Hangzhou China

An adaptive color image filter (ACIF) is proposed in this note. Through analyzing noise corruption of color image, efficient locally adaptive filters are chosen for image enhancement. The proposed adaptive color image filter combines advantages of both nonlinear vector filters and linear filters, it attenuates noise and preserves edges and details very well. Experimental results show that the proposed filter performs better than vector median filter, directional-distance filter, directional-magnitude vector filter, adaptive nearest-neighbor filter, and α-trimmed mean filter.

关键词： color image noise analysis locally adaptive filters adaptive color image filter (ACIF).

Probing proton halo of the exotic nucleus ^(2.)S by elastic electron scattering

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science china(Physics,Mechanics & Astronomy) 2004年第1期47卷 42-51页

作者： WANG Zaijun1 & REN Zhongzhou1’2.1. department of Physics, nanjing {2., nanjing 2.0008, china 2. Center of Theoretical Nuclear Physics, National Laboratory of Heavy-Ion Accelerator at Lanzhou, Lanzhou 730000, china correspondence should be addressed to Ren Zhongzhou (email: zren@*** zren99@***) Received June 16, 2.03 department of Physics Nanjing University Nanjing 210008 China Center of Theoretical Nuclear Physics National Laboratory of Heavy-Ion Accelerator at Lanzhou Lanzhou 730000 China

Elastic electron scattering on the exotic light nucleus 2.S is investigated in the plane wave Born approximation. The variation of the squared form factors of 2.S with momentum transfer is compared with that of 32.. It is found that the behavior of the form factors near the second minimum (with a moderate momentum transfer) is sensitive to the alteration of the charge density distribution of halo protons in 2.S. This indicates that elastic electron scattering can be a good probe of the structure of proton-halo nuclei.

关键词： elastic electron scattering, cross section, form factor, proton-halo nucleus.

Effect of excess Y_2._3 addition on the physical properties of melt processed YBCO bulks

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science china(Physics,Mechanics & Astronomy) 2004年第1期47卷 17-23页

作者： YANG Wanmin1,2.3, ZHOU Lian2. FENG Yong2. ZHANG Pingxiang2. WU Minzhi3 & W. GAWALEK3 1. department of Physics, Shaanxi Normal university, Xi抋n 710062. {2. 2. Northwest Institute for Nonferrous Metal Research. Xi抋n 710016, {2. 3. Institute fur Physikalische Hochtechnologie e.V(IPHT), Jena, Germany correspondence should be addressed to Yang Wanmin (email: wm-yang@***) Received June 2., 2.03 department of Physics Shaanxi Normal University Xi'an 710062 China

The YBCO superconductors with Y2.3 addition were prepared by a modified melt textured process and the effects of excess Y2.3 addition on the physical properties of melt textured YBCO have been investigated. It is found that the melt temperature of YBCO samples decreases drastically with the increasing Y2.3, and the maximum levitation forces are drastically different for samples with different Y2.3 addition. It is also found that the optimal Y2.3 addition to YBCO is about 10wt%. Considering the microstructure and the starting composition, the results are well discussed and interpreted.

关键词： YBCO superconductor, melt growth, Y2.3 addition, levitation force.

Investigation of solvatochromism and aggregation behavior of C_(60)(C_4H_(10)N^+)I^- in binary solvent mixtures

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Chinese science Bulletin 2003年第18期48卷 1938-1942页

作者： WANG Guanwu1, HAO Erhong1, jiAO Lijuan1 & YAN lifeng2.1. department of Chemistry, {2. of science and Technology ofchina, Hefei 2.002., china 2. department of Chemical Physics, {2. of science and Technol-ogy of china, Hefei 2.002., china correspondence {{12. be addressed to Wang Guanwu (e-mail: gwang @***) department of Chemistry University of Science and Technology of China Helei 230026 China

Water-soluble N,N-dimethyl[60]fulleropyrro-lidinium iodide (C60(C4H10N+)I-), when dissolved in binarymixtures of tetrahydrofuran and water, was found to exhibit remarkable solvatochromism. Correspondingly, the UV-vis spectra showed obvious changes by variation of the solventcomposition of tetrahydrofuran and water. It was found that both concentration and temperature had strong influence on the stability of monomer-state C60(C4H10N+)I-, while theyhad little effect on the stability of aggregated C60(C4H10N+) I-The formation of cluster was confirmed by TEM and AFMmeasurements.

关键词： N N-dimethylfulleropyrrolidinium iodide solvato-chromism aggregation.

Epigenetic reprogramming in mammalian nuclear transfer

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Chinese science Bulletin 2004年第8期49卷 766-771页

作者： LI Shijie1,2. DU Weihua1 & LI Ning1 1. State Key Laboratory for Agrobiotechnology, china Agricultural university, Beijing 100094, china 2. department of Biochemistry and Molecular Biology, College of life science, Hebei Agriculture university, Baoding 071001, china correspondence should be addressed to Li Ning (e-mail: ninglbau@ ***) State Key Laboratory for Agrobiotechnology China Agricultural University Beijing 100094 China department of Biochemistry and Molecular Biology College of Life Science Hebei Agriculture University Baoding 071001 China

Somatic cloning has been succeeded in some species, but the cloning efficiency is very low, which limits the application of the technique in many areas of research and biotechnology. The cloning of mammals by somatic cell nuclear transfer (NT) requires epigenetic reprogramming of the differentiated state of donor cell to a totipotent, embry-onic ground state. Accumulating evidence indicates that in-complete or inappropriate epigenetic reprogramming of do-nor nuclei is likely to be the primary cause of failures in nu-clear transfer. This review summarizes the roles of various epigenetic mechanisms, including DNA methylation, histone acetylation, imprinting, X-chromosome inactivation, te-lomere maintenance and expressions of development-related genes on somatic nuclear transfer.

关键词：哺乳动物细胞核液迁移后成程序改编 DNA甲基化作用组蛋白乙酰化作用 X-染色体活化端粒印痕基因表达克隆

On the new results of global attractive set and positive invariant set of the Lorenz chaotic system and the applications to chaos control and synchronization

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science in china(Series F) 2005年第3期48卷 304-321页

作者： LIAO Xiaoxin 1, 2. 3 , FU Yuli 4 & XIE Shengli 4 1. department of Control science & Control Engineering, Huazhong {2. of science & Technology, Wuhan 430074, china 2. School of Automation, Wuhan {2. of science & Technology, Wuhan 430070, china 3. School of Information, Central South {2. of Economy, Politics and Law, Wuhan 430064, china 4. School of Electronics & Information Engineering, South china {2. of Technology, Guangzhou 510640, china correspondence should be addressed to Liao Xiaoxin (email: xiaoxin_liao@***) department of Control science & Control Engineering Huazhong University of Science & Technology Wuhan 430074 China

Constructing a family of generalized Lyapunov functions, a new method is proposed to obtain new global attractive set and positive invariant set of the Lorenz chaotic system. The method we proposed greatly simplifies the complex proofs of the two famous estimations presented by the Russian scholar Leonov. Our uniform formula can derive a series of the new estimations. Employing the idea of intersection in set theory, we extract a new Leonov formula-like estimation from the family of the estimations. With our method and the new estimation, one can confirm that there are no equilibrium, periodic solutions, almost periodic motions, wandering motions or other chaotic attractors outside the global attractive set. The Lorenz butterfly-like singular attractors are located in the global attractive set only. This result is applied to the chaos control and chaos synchronization. Some feedback control laws are obtained to guarantee that all the trajectories of the Lorenz systems track a periodic solution, or globally stabilize an unstable (or locally stable but not globally asymptotically stable) equilibrium. Further, some new global exponential chaos synchronization results are presented. Our new method and the new results are expected to be applied in real secure communication systems.

关键词： Lorenz chaotic system global attractive set positive invariant set globally exponential tracking globally exponential synchronization.

Adsorption of CO molecules on Rh low index and (331)stepped surfaces

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Chinese science Bulletin 2004年第10期49卷 1012-1019页

作者： WANG Zexin PANG Xuehui WANG Rui Chemistry department, shandong Normal {2., jinan 2.0014,china correspondence should be addressed to Wang Zexin Chemistry department Shandong Normal University Jinan 250014 China

The 5-parameter Morse potential (for short5-MP) of the interaction between C, O atom and Rh surfaceand the extended LEPS potential have been constructed, andthe adsorption and diffusion of CO molecules on Rh low in-dex surfaces and open rough Rh(331) stepped surface areinvestigated. This work puts forward the concept of vibra-tion dactylogram property for molecular adsorption *** calculation results and the analysis of vibration dactylo-gram show that there exists the commonness in the adsorp-tion on Rh low index surfaces and Rh(331) stepped surface: with the increasing coverage, the top, bridge sites are ad-sorbed in perpendicularly in sequence, and the top sites arethe steady adsorption sites and the bridge sites are the *** (100) surface, CO molecules obtain the eigenvibration of2.09, 1946 cm^-1 on the top and bridge sites respectively andthe difference between the binding energy of above two sitesis 0.09 eV; on (110) surface, CO molecules obtain the eigen-vibration of 2.19, 1961 cm^-1 respectively; on (111) surface,CO molecules on the top. bridge and hollow sites produce theeigenvibration of 2.00, 1912. 1894 cm^-1 respectively, thebinding energies of the three sites decrease in turn and thediscrepancy between the top and bridge sites is 0.03 eV; on (331) surface, top and bridge sites between two equivalenttop sites are adsorbed in, and then obtain the eigenvibrationof 2.18, 1987 cm^-1; 1969, 192. cm^-1 respectively.

关键词：一氧化碳铑 5-MP 扩展LEPS电势表面吸附陆地指纹本征振动

Structural pattern of eastern Himalayan syntaxis in Namjagbarwa and its formation process

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science china Earth sciences 2004年第2期47卷 138-150页

作者： ZHANG jinjiang, Jl jianqing, ZHONG Dalai, DING Lin & HE Shundong1. department of Geology, Peking university, Beijing 100871, {2. 2. Institute of Geology and Geophysics, Chinese Academy of sciences, Beijing 10002., {2. correspondence should be addressed to Zhang jinjiang (email: zhjj@***) department of Geology Peking University Beijing China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China

The structural pattern of the eastern Himalayan syntaxis in Namjagbarwa consists of two series of structures with different styles. One series compiles the earlier ductile contractional and lateral-slip deformation system, formed by nearly north-south shortening within the syntaxis, left-lateral and right-lateral slipping along its western and eastern boundaries respectively. They were possibly produced by the indentation of the Indian continent into Asian continent after India-Asia collision. The peak deformation-metamorphic ages in these structures are 62.60 Ma, ~2. Ma and ~13 Ma. The other series is composed of ductile-brittle normal faults distributing concentrically and dipping toward the outsides of Namjagbarwa Peak. They were probably the collapse structures caused by rapid uplift in a later time and the beginning ages for the normal faulting are about 7.3-6.3 Ma. Keywords Namjagbarwa - eastern Himalayan syntaxis (EHS) - structural pattern - formation process - structural chronology

关键词： Namjagbarwa, eastern Himalayan syntaxis (EHS), structural pattern, formation process, structural chronology.