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Wear Performance of Laser Surface Hardened GCr15 Steel

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Journal of Wuhan University of Technology(Materials science) 2010年第1期25卷 84-88页

作者：雷声 School of Materials science and engineering Hefei University of Technology department of Electromechanical engineering Anhui Institute of Architecture and Industry

In order to assess the new tribological properties of laser surface hardened GCr15 steel, the wear resistance between specimens treated with laser and those of conventionally hardened under dry sliding conditions was compared. The change of wear mechanisms in laser hardened GCr15 resulted in a distinct difference in wear rates. The results showed that quenched zones not only had sufficient depth of hardening and higher hardness, but had more retained austenite and finer carbides because of a higher degree of carbide dissolution. Laser surface hardened GCr15 steel specimens exhibited superior wear resistance to their conventionally hardened specimens due to the effects of the microstructure hardening, high hardness and toughness. The wear mechanism for both the laser quenched layer and conventionally hardened layer was highly similar, generally involving adhesive, material transfer, wear-induced oxidation and plowing. When conventionally hardened block specimens rubbed against the laser hardened specimens, the surface of conventionally hardened block specimens was polished. The microstructural thermal stability was increased after laser surface treatment.

关键词： laser hardening dry sliding conditions GCr15 steel wear mechanisms

The optical near-field speckles and their first order statistics on the basis of the integral equations of electromagnetic field

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science china(Physics,Mechanics & Astronomy) 2004年第3期47卷 365-380页

作者： CHENG Chuanfu1, 2. SONG Hongsheng2. LIU Chunxiang2. REN xiaorong2. ZHANG Ningyu3, TENG Shuyun1 & XU Zhizhan1 1. Shanghai institute of Optics and Fine Mechanics, Chinese Academy of sciences, P. O. Box 800-2.1, Shanghai 2.1800,{2. 2. department of Physics, Shandong Normal University, Jinan 2.0014,{2. 3. Shandong institute of architecture and engineering, Jinan 2.0014,{2. Shanghai institute of Optics and Fine MechanicsChinese Academy of sciencesShanghai{2. department of PhysicsShandong Normal UniversityJinanchina Shandong institute of architecture and {2.Jinanchina

From Helmholtz equation of the harmonic electromagnetic waves, the integral equations of the light field at the medium boundaries are obtained by use of the Green's theorem and are discretized into linear equation set with the values of the light field and its derivative as the unknowns. On solving the linear equation set, we realize the rigorous computations of the light fields at the boundaries. Then the intensities of the light waves scattered by the random self-affine fractal surfaces in the optical near-field are calculated, and the propagation characteristics, the evolutions of the contrast and the intensity probability density function of the near-field speckles are studied in detail. The near-field speckles are much different from the conventional speckles in the diffraction regions and in the imaging systems. There are obvious local fluctuations in the intensity distributions of the near-field speckles and such fluctuations disappear after propagating a distance of one wavelength from the medium surfaces. For the random surfaces with smaller lateral correlation lengths, the speckle contrasts approach the saturation values and the speckle fields approach Gaussian distribution within the near-field, while for the random surfaces with larger lateral correlation lengths, such evolutions become comparatively slow.

关键词： speckle, near-field optics, first order statistics, Green's function.

Radiative lifetimes of Rydberg states of BeⅠand BeⅢ

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原子与分子物理学报 2003年第4期20卷 575-578页

作者： LIANG Liang~(1,2., WANG Yong-chang~1 (1. institute of modern Physics, School of science, xi’an Jiaotong University, xi’an 710049, P. R.{2. 2. department of Physics, xi’an University of architecture and Technology, xi’an 710055, P. R.{2.) institute of moderm Physics School of scienceXi'an Jiaotong University Xi'an 710049

By using the multichannel quantum defect theory （MQDT）, we have evaluated the energy levels and lifetimes of 2.ns （）3S1,2.nd（）3D（n=3-2.） of BeⅠ and 1sns（）3S1,1snd （）3D（n=3-2.） of BeⅢ. These energies and lifetimes that we have calculated not only agree with the recent measurements and theoretical calculation of Ref.4 and Ref.3, but also predict the lifetimes of 66 other highly excited states.

关键词：辐射寿命里德伯态多道量子缺陷理论铍元素原子高激发态原子物理学

Two-dimensional simulation of Poiseuille-Rayleigh-Bénard flows in binary fluids with Soret effect

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Progress in Natural science:Materials International 2007年第12期17卷 1389-1396页

作者： Hu Jun1 and Yin xieyuan2.1. institute of Applied Physics and Computational Mathematics, Beijing 100088, china 2. {2. of Modern Mechanics, University of science and Technology of china, Hefei 2.002., china) institute of Applied Physics and Computational Mathematics Beijing 100088 China department of Modern Mechanics University of Science and Technology of China Hefei 230027 China

Poiseuille-Rayleigh-Bénard flows in binary fluids with Soret effect are directly simulated by a mixed finite element method. A temperature perturbation is used as an initial disturbed source for the basic parallel flows. The whole spatio-temporal evolution of the binary fluid flows is exhibited: initially only the disturbed mode with the wavenumber k=π is amplified while others are damped, and continuously the amplified mode grows further and the nonlinear effect becomes important; after a nonlinear evolution transition the flow system evolves finally into a periodic right traveling wave.

关键词： Poiseuille-Rayleigh-Bénard flow Soret effect through-flow.

Recurrence spectra of He atoms in strong external fields

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science china(Physics,Mechanics & Astronomy) 2004年第4期47卷 477-484页

作者： LIN Shenglu1, LI Hongyun1, WANG Dehua2. ZHAO Wenli1 & GAO Feng1 1. department of Physics, Shandong Normal University, Jinan 2.0014, china 2. department of Mathematics and Physics, Shandong institute of architecture and engineering, Jinan 2.0014, china department of Physics Shandong Normal University Jinan China department of Mathematics and Physics Shandong Institute of Architecture and Engineering Jinan China

By employing a model potential including the electron exchange energy, we extend the semiclassical closed orbit theory to study the multielectron atoms. Using special region-splitting consistent and iterative method, we figure out the closed orbits in the corresponding classical system and calculate the recurrence spectra of triplet helium atoms in parallel electric and magnetic fields at scaled energy ε=?0.03,n≈40,n=0. The core-scattering effects have been taken into account, which lead to more peaks in the spectra. It has also been confirmed by means of the direct comparison between the spectral portrait in such a plot and those of hydrogen case. In order to compare the theoretic results with experiment, we investigate the closed orbits and recurrence spectra of helium atoms for the similar exchange potential but applied only by single electric field at scaled energy ε=?2.7 case. The spectra are in good agreement with the experimental observation. We conclude that our model is correct and it is necessary to consider the exchange effect for determining the photoabsorption spectra of multielectron atoms in strong external fields.

关键词： exchange potential, recurrence spectra, semiclassical closed orbit theory, core-scattering.

On three-dimensional geological modeling and visualization

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science china Earth sciences 2004年第8期47卷 739-748页

作者： WU Qiang1 & XU Hua2.1. department of Resource Exploitation engineering,{2. University of Mining and Technology, Beijing 100083,{2. 2. Beijing institute of Petrochemical Technology, Beijing 102.17,{2. department of Resource Exploitation engineering China University of Mining and Technology Beijing China Beijing institute of Petrochemical Technology Beijing China

The technology of 3D geological modeling will bring about great changes in the methods of geological data acquiring, storing, processing and displaying. However, no perfect or convenient software systems have been developed up to now since the geologic data which re-flect geological entities bear the feature of diversity, uncertainty and complexity. Some supervoxel models, mathematical models of fault and geometrical models of fold have been contrived so as to show the space geometric configuration of the complicated geologic structures. The application-oriented system architecture for 3D geological modeling is established; and a novel design concept based on spatial data processing is also proposed with the technology of solid modeling as its core and the application of models as its objective. Theories and methods for 3D geological modeling will hopefully be enriched and developed. In the light of these theories and methods, a feature-based navigation visualization technique is also put forward in the paper. By integrating geo-database, graphics libraries and KBS with 3D dynamic simulation systems, geologists will be able to capture the partial characteristics and whole structure embodied in the geological data in a direct-viewing, figurative and accurate manner.

关键词： 3D geological modeling,geometrical model,system architecture,visualization

Morita contexts on the Hopf algebroid

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science china Mathematics 2005年第7期48卷 958-971页

作者： YIN Yanmin School of Mathematical sciences, Peking University, Beijing 100871, china {2. of Mathematics, Shandong institute of architecture and engineering, Jinan 2.0101, china School of Mathematical sciences Peking University Beijing 100871 China department of Mathematics Shandong Institute of Architecture and Engineering Jinan 250101 China

We generalize the Morita theory to the Hopf algebroid and give the characterization of the surjectivity of one of the Morita context maps.

关键词： comodule algebra, generalized smash product, Morita context.

An improved approach to the efficient construction of and search operations in motion graphs

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science china(Information sciences) 2012年第5期55卷 1042-1051页

作者： GAO Yan 1,CHEN ZhiHua 2.CHEN MinGang 3 & SHEN Yang 3 1 Software engineering institute,East{2. Normal University,Shanghai 2.0062.china 2.department of Computer science and engineering,East{2. University of science and Technology,Shanghai 2.02.7,china 3 department of Computer science and engineering,Shanghai Jiao Tong University,Shanghai 2.02.0,china Software engineering institute East China Normal University Shanghai China department of Computer science and {2. East China University of Science and Technology Shanghai China department of Computer science and {2. Shanghai Jiao Tong University Shanghai China

Motion graphs have been widely used as an effective technique in the synthesis of human *** synthesize well-formed motions,motion graphs require smooth transitions and good ***,the time and costs grow quadratically as the graph size *** this paper,we present a method to set up a hierarchical structure,called a structure *** coarse level of this graph models different motion categories and their transitions,and the fine level mainly captures different motion *** interpolation space method is used to improve the graph connectivity at the fine *** structure guides the establishment of a faster and more realistic graphical *** the building process,this structure also helps with searching the motion graph,by performing a traverse search and placing the findings into a direct look-up table or local search ***,when there is no direct link between the different motions,a navigation map is introduced to conduct an appropriate search path via a series of transition motion *** experimental results indicate that our approach could lower the computation time in construction and searching,while simultaneously providing a richer variety of motion styles.

关键词： motion graph structure table registration curve motion interpolation

Lie symmetries of mechanical systems with unilateral holonomic constraints

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Chinese science Bulletin 2000年第15期45卷 1354-1358页

作者： ZHANG Yi & MEI Fengxiang1. department of basic Courses, Suzhou {2. of Urban Construction & Environmental Protection, Suzhou 2.5011, china 2. department of Applied Mechanics, Beijing {2. of Technology, Beijing 10008I, china department of basic Courses Suzhou Institute of Urban Construction & Environmental Protection Suzhou China department of Applied Mechanics Beijing Institute of Technology Beijing China

In the recent twenty years, the study on the Lie symmetries and conserved quantities of constrained mechanical systems has been making great progress[1-5]. Up to now, however, all the studies are limited to the mechanical systems with ideal bilateral constraints. This note further studies the Lie symmetries of mechanical systems with unilateral holonomic constraints, and two problems of Lie symmetries for the systems are put forward and solved, i.e. finding the conserved quantity from a Lie symmetric transformation of the system and finding the corresponding Liesymmetry from an integral of the systemi ? 梛 ? Jsymmetry from an integral of the system.

关键词： analytical mechanics unilateral constraint holonomic system Lie symmetry conserved quantity.