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Universality and Specificity of Fractal Dimension of Fractured Surfaces in Materials

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Journal of Materials Science & Technology 2000年第1期16卷 1-4页

作者： Chiwei LUNG and Shenggang WANG (international Centre for Materials physics, Institute of Metal Research,{2., shenyang 110015, china) international Centre for Materials physics Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China

After calculation on the fracture angles under various conditions of specific surface energies with different symmetry operations of rotation, the complicated behavior of dependence of fractal dimension on the structure of crystal is shown. It is found that the crack propagates along the weakest crystal plane no matter what the direction of the maximum stress is if the anisotropy is sufficiently strong; and then, the fractal dimension of the fractured surfaces might be determined by the approximate fractal structure already existed in the material. Specificity of the fractal dimension of fractured surfaces would be easy to appear in this case. Reversely, the crack propagates along the direction of the maximum stress no matter what direction of the weakest crystal plane is if the anisotropy is sufficiently weak. Universality of the fractal dimension of fractured surfaces would be possible to appear in this case. In many real materials, universality and specificity of the materials are associated. The fractal dimension measured may more or less be influenced by the structure of materials and it shows its universality through the specificity of materials.

关键词： Universality and Specificity of Fractal Dimension of Fractured Surfaces in Materials

Calculation of the Surface Segregation of Cu-0.3 at. pct Au Alloy

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Journal of Materials Science & Technology 2000年第6期16卷 639-640页

作者： Liping ZHENG and Risheng LI (international center for Material {2., chinese academy of sciences, shenyang 110015, china) Yuanxun ZHANG and Shi QIU (Shanghai Institute of Nuclear Research, chinese academy of sciences, Shanghai 2.1800, china) Bingyao JI Int. Cent. for Material Phys. Chinese Acad. of Sci. Shenyang 110015 China

Monte Carlo simulation technique with the energetics described by the embedded atom method has been used to calculate the surface segregation of Cu-0.3 at. pct Au alloy at T=800 K. It is found that the component Au in... 详细信息

关键词： Cu Calculation of the Surface Segregation of Cu-0.3 at pct Au Alloy

The effect of hydrogen on the electronic structure of kink in bcc iron

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Science china(Technological sciences) 2009年第5期52卷 1212-1218页

作者： CHEN LiQun1,QIU ZhengChen1,YU Tao2.& WANG ChongYu2.3,4 1 College of sciences,Central South University of Forestry and Technology,Changsha 410004,china 2.Central Iron and Steel Research Institute,Beijing 100081,china 3 Department of physics,Tsinghua University,Beijing 100084,china 4 international center for Materials physics,chinese academy of sciences,shenyang {12.,china College of sciences Central South University of Forestry and Technology Changsha China Central Iron and Steel Research Institute Beijing China Department of physics Tsinghua University Beijing China international center for Materials {2. Chinese Academy of Sciences Shenyang China

The electronic structures of kinks in the [100](010) and 1/2.111](-110) edge dislocations in bcc iron containing hydrogen are investigated by means of the first-principles DMol method and the discrete variational *** effects of hydrogen on the kinks are *** results show that hydro-gen forms weak bonding states with its neighboring host atoms,and since hydrogen draws charge from its neighboring host atoms,the interactions between most of the host atoms are weakened com-pared with those of the corresponding atomic pairs in the clean *** indicates that the migration of kink,*** motion of dislocation,is easier in the doping hydrogen kink than in the clean kink,which may be the solid solution softening effect resulting from the impurity hydrogen.

关键词： electronic structure dislocation kink impurity

Forecasting the summer rainfall in North china using the year-to-year increment approach

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Science china Earth sciences 2009年第4期52卷 532-539页

作者： FAN Ke1, LIN MeiJing1,2.& GAO YuZhong3 1 Nansen-Zhu international Research center, Institute of Atmospheric {2., chinese academy of sciences, Beijing 10002., china 2.Graduate University of the chinese academy of sciences, Beijing 100049, china 3 Heilongjiang Meteorological Administration, Harbin 150030, china Nansen-Zhu international Research center Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Graduate University of the chinese academy of sciences Beijing China Heilongjiang Meteorological Administration Harbin China

A new approach to forecasting the year-to-year increment of rainfall in North china in July-August (JA) is proposed. DY is defined as the difference of a variable between the current year and the preceding year (year-to-year increment). NR denotes the seasonal mean precipitation rate over North china in JA. After analyzing the atmospheric circulation anomalies associated with the DY of NR, five key predictors for the DY of NR have been identified. The prediction model for the DY of NR is established by using multi-linear regression method and the NR is obtained (the current forecasted DY of NR added to the preceding observed NR). The prediction model shows a high correlation coefficient (0.8) between the simulated and the observed DY of NR throughout period 1965-1999, with an average relative root mean square error of 19% for the percentage of precipitation rate anomaly over North china. The prediction model makes a hindcast for 2.00-2.07, with an average relative root mean square error of 2.% for the percentage of precipitation rate anomaly over North china. The model reproduces the downward trend of the percentage of precipitation rate anomaly over North china during 1965-2.06. Because the current operational prediction models of the summer precipitation have average forecast scores of 60%-70%, it has been more difficult to forecast the summer rainfall over North china. Thus this new approach for predicting the year-to-year increment of the summer precipitation (and hence the summer precipitation itself) has the potential to significantly improve operational forecasting skill for summer precipitation.

关键词： annual increment North china precipitation prediction prediction skill

2.5-dimensional angle potential field algorithm for the real-time autonomous navigation of outdoor mobile robots

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Science china(Information sciences) 2011年第10期54卷 2100-2112页

作者： QIU Quan 1,3 & HAN JianDa 2.1 Beijing Research center of Intelligent Equipment for Agriculture,Beijing 100097,china 2.State Key Laboratory of Robotics,{2. Institute of Automation,chinese academy of sciences,{2. 110016,china 3 National Research center for Intelligent Agricultural Equipment,Beijing 100097,china Beijing Research center of Intelligent Equipment for Agriculture Beijing China National Research center for Intelligent Agricultural Equipment Beijing China State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences Shenyang China

A new real-time algorithm for the autonomous navigation of mobile robots equipped with laser scanners is proposed in this *** from the existing algorithms designed for 2.dimensional navigation problems,the new algorithm introduces the height information of the obstacles into the guidance process and behaves as a 2.5-dimensional angle potential field algorithm (2.5D-APF) to fulfill the navigation requirements under complex outdoor terrain ***,one laser scan is partitioned into two kinds of function sectors: guidance sector and inspecting ***,the guidance sector and the inspecting sectors are reconstructed to form a virtual guidance scan,where the 2.5D information is taken into ***,the conventional APF is improved to analyze the virtual guidance scan and generate the navigation *** new algorithm is tested on a tracked mobile robot,and the experimental results validate the proposed algorithm.

关键词： robot 2.5-dimensional outdoor real-time autonomous navigation

Comparison of dark energy models:A perspective from the latest observational data

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中国科学：物理学、力学、天文学英文版 2010年第9期53卷 1631-1645页

作者： LI Miao1,2.LI XiaoDong2.3 & ZHANG Xin1,4 1Kavli Institute for Theoretical physics china,{2. academy of sciences,Beijing 100190,china 2.ey Laboratory of Frontiers in Theoretical physics,Institute of Theoretical physics,{2. academy of sciences,Beijing 100190,china 3Interdisciplinary {12. for Theoretical Study,University of Science and Technology of china,Hefei 2.002.,china 4Department of physics,College of sciences,Northeastern University,shenyang 110004,china Kavli Institute for Theoretical physics china Chinese Academy of Sciences Beijing China Key Laboratory of Frontiers in Theoretical physics Institute of Theoretical Physics Chinese Academy of Sciences Beijing China Interdisciplinary center for Theoretical Study University of Science and Technology of China Hefei China Department of physics College of Sciences Northeastern University Shenyang China

We compare some popular dark energy models under the assumption of a flat universe by using the latest observational data including the type Ia supernovae Constitution compilation,the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey,the cosmic microwave background measurement given by the seven-year Wilkinson Microwave Anisotropy Probe observations and the determination of H0 from the Hubble Space *** comparison statistics such as the Bayesian and Akaike information criteria are applied to assess the worth of the *** statistics favor models that give a good fit with fewer *** on this analysis,we find that the simplest cosmological constant model that has only one free parameter is still preferred by the current *** other dynamical dark energy models,we find that some of them,such as the αdark energy,constant w,generalized Chaplygin gas,Chevalliear-Polarski-Linder parametrization,and holographic dark energy models,can provide good fits to the current data,and three of them,namely,the Ricci dark energy,agegraphic dark energy,and Dvali-Gabadadze-Porrati models,are clearly disfavored by the data.

关键词： dark energy models observational constraints model comparison information criteria

Microstructure characterization of high-energy product Nd-Fe-B thin film

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Progress in Natural Science:Materials international 2010年第1期20卷 76-80页

作者： Fang XU~1,Fang YANG~2.Xian-ping DONG~1,Lan-ting ZHANG~1,Wei LIU~2.Zhi-dong ZHANG~2.1.School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 2.02.0,china 2.shenyang National Laboratory for Materials Science,Institute of Metal Research and {2. Centre for Materials physics,chinese academy of sciences,shenyang 110016,china School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China shenyang National Laboratory for Materials Science Institute of Metal Research and International Centre for Materials Physics Chinese Academy of Sciences Shenyang 110016 China

A Si/Mo（50 nm）/Nd-Fe-B（400 nm）/Mo（50 nm）film with relatively high-energy product（BH）max=2.7 kJ/m3)was prepared on a Si substrate heated at 650℃.The microstructure of the film was investigated by X-ray diffractometry（XRD）and high-resolution transmission electron microscopy（HRTEM）.The Nd-Fe-B thin film shows a notable out-of-plane c-axis *** （110）orientated Mo grains is proved to promote the growth of c-axis oriented texture of the Nd2.e14B grains,which is favorable to achieve a high ***-scale spherical Nd-O phases composed of randomly orientated polycrystalline grains and a sharp grain boundary without grain boundary phase between two Nd2.e14B grains are *** coercivity highly depends on a certain amount of Nd-O phase and interface morphology.

关键词： Nd-Fe-B thin films microstructure Nd-O phase magnetic properties

Energy Spectrum of YAG:Cr3+ and Thermal Shifts of Its R Lines

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Communications in Theoretical physics 2005年第7期44卷 165-170页

作者： MA Dong--Ping CHEN Ju--Rong Department of Applied physics, Sichuan University, Chengdu 610065, china {2. Centre for Materials physics, the chinese academy of sciences, shenyang 110015, china Department of Applied physics Sichuan University Chengdu 610065 China international Centre for Materials physics the Chinese Academy of Sciences Shenyang 110015 China

Traditional ligand-field theory has to be improved bv taking into account both "pure electronic" contributionand electron-phonon interaction one （including lattice-vitbrational relaxation energv）. By means of improved ligand-fieldtheory, R1, R2. R3′, R2., and R1′ lines, U band, ground-state zero-field-splitting （GSZFS） and ground-state g factors aswell as thermal shifts of R1line and R2.ine of YAG:Cr3+have been calculated. The results are in very good agreementwith the experimental data. In contrast with ruby, the octahedron of ligand oxygen ions surrounding the central Cr3+ion in YAG:Cr3+is compressed along the [111] direction. Thus, for YAG:Cr3+and ruby, the splitting of t2. 4A2.or t2. 2.)has opposite order, and the trigonal-field parameters of the two crystals have opposite signs. In thermal shifts of R1andR2.ines of YAG:Cr3+, the tetnperature-dependent contributions due to EPI are dominant.

关键词： improved ligand-field theory electron-phonon interaction Stokes shift energy spectrum thermal shift g factor

Modeling diameter distribution of the broadleaved-Korean pine mixed forest on Changbai Mountains of china

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Science china(Technological sciences) 2006年第Z1期49卷 177-188页

作者： WANG Shunzhong, DAI Limin, LIU Guohua, YUAN Jianqiong, ZHANG Hengmin & WANG Qingli Institute of Applied Ecology, chinese academy of sciences, shenyang 110016,{2. Graduate University of chinese academy of sciences, Beijing 100039,{2. State Key Lab of Systems Ecology, Research center for Eco-Environmental sciences, chinese academy of sciences, Beijing 100085,{2. Institute of Applied Ecology Chinese Academy of Sciences Shenyang China Graduate University of chinese academy of sciences Beijing China State Key Lab of Systems Ecology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing China

The broadleaved-Korean pine mixed forest is a native vegetation in the Changbai Mountains, northeast china. The probability density functions including the normal, negative exponential, Weibull and finite mixture distribution, were used to describe the diameter distributions of the species groups and entire forest stand. There is a strong correlation between parameters and mean DBH except the shape parameters in the mixture distribution. The diameter classes of species and entire forest stand showed not negative exponential but normal and "S" distribution. The mixture function was better than normal and Weibull to describe the model distribution. The location parameter had an effect on the estimated frequency in the first diameter class, when the estimated location parameter was bigger than the lower limit of the first diameter class.

关键词： broadleaved-Korean pine mixed forest, diameter distribution, finite mixture distribution.