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Numerical simulation of strain localization and damage evolution in large plastic deformation using mixed finite element method

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Journal of university of science and technology beijing 2004年第3期11卷 273-277页

作者： Zhanghua Chen Jiajian Jin jiumei xiao {2. science School, university of science and technology beijing, beijing 100083, china Appl. Sci. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

An investigation of computer simulation is presented to analyze the effectsof strain localization and damage evolution in large plastic deformation. The simulation is carriedout by using an elastic-plastic-damage coupling finite element program that is developed based onthe concept of mixed interpolation of displacement/pressure. This program has been incorporated intoa damage mechanics model as well as the corresponding damage criterion. To illustrate theperformance of the proposed approach, a typical strain localization problem has been simulated. Theresults show that the proposed approach is of good capability to capture strain localization andpredict the damage evolution.

关键词： strain localization mixed element truesdell stress rate material damage

Effects of applied Magnetic Field on Corrosion of Beryllium Copper in NaCl Solution

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Journal of Materials science & technology 2010年第4期26卷 355-361页

作者： Jing Hu, Chaofang Dong, xiaogang Li and Kui xiao Corrosion & Protection Center,{2., Key Laboratory for Corrosion and Protection of Ministry of Education, beijing 100083, china Corrosion & Protection Center University of Science and Technology Beijing Key Laboratory for Corrosion and Protection of Ministry of Education Beijing 100083 China

The effects of an applied magnetic field on the corrosion process of beryllium copper in NaCl solution have been investigated by electrochemical measurements, scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）. The results showed that a horizontal magnetic field with 0.4 T barely shifted the open circuit potentials （Ecorr） of beryllium copper in NaCl solution with different concentrations. However, the horizontal magnetic field increased the limiting current density of beryllium copper in NaCl solution with low concentration, while decreased the limiting current density of beryllium copper in NaCl solution with high concentration. It was found that magnetic field accelerated the diffusion of CuCl2. away from the electrode surface and delayed the formation of Cu2.. The results of SEM and EDS showed that the inffuence of magnetic field over the elements distribution of the corrosion products differed from the different concentration of the immersion solution.

关键词： Beryllium copper Magnetic field Corrosion

SEM In-situ Observation at Tensile Loading on Surface Inclusion in PM Rene95 Superalloy

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Journal of university of science and technology beijing 2001年第4期8卷 286-289页

作者： xiao Li, Lina Zhang, Jianxin Dong, Maicang Zhang, Yaohe Hu, Xishan Xie Materials science and Engineering School.{2.. beijing 100083. china Materials science and Engineering School University of Science and Technology Beijing Beijing 100083 China

The observation on crack initiation and propagation of surface inclusion Al2.3 in seeded PM Rene95 was conducted by SEM in-situ tension test. The results show that the cracks often initiate at the inclusion/matrix interface vertical to the applied stress direction, and easily propagate along the interface into the matrix. The interface of inclusion/matrix is just mechanically bounded on the base of SEM observation. The weak bonding of inclusion/matrix interface and stress concentration around inclusions are the main reasons of the matrix/inclusion interface debonding and local plastic deformation under the tensile loading in the in-situ tension test. Surface inclusion does not definitely lead to the failure of in-situ tension test. But the early surface crack initiation caused by ceramic inclusion is critically harmful to the LCF property of PM Rene95 superalloy, which can't be ignored.

关键词： inclusions SEM in-situ observation PM Rene95 stress concentration

Real estate appraisal system based on GIS and BP neural network

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中国有色金属学会会刊：英文版 2011年第S3期21卷 626-630页

作者： LIU xiao-sheng1, DENG Zhe1, WANG Ting-li2.1. School of Architecture and Survey Engineering, Jiangxi university of {2. and technology, Ganzhou 341000, china 2. School of applied {2., Jiangxi university of {2. and technology, Ganzhou 341000, china School of Architecture and Survey Engineering Jiangxi University of Science and Technology Ganzhou 341000 China School of applied science Jiangxi University of Science and Technology Ganzhou 341000 China

For the inefficiency and inaccuracy of appraisal method of traditional estate appraisal theory, the real estate appraisal system based on GIS and BP neural network was established. The structure of the system was designed which includes appraisal model, trade case, GIS database and query analysis module. With the help of the L-M algorithm in MATLAB software, BP neural network was improved and the trade cases were trained, then the BP neural network which has already been trained was tested. At the same time, the BP neural and GIS were put together to construct the hedonic price estimate model. The C# and ArcGIS9.3 were used to achieve the system in VS2.08. City basic geographic data and real estate related information were used as the basic data in practice. The results show that the functions of querying, adding and editing the spatial data and attribute data are achieved and also the efficiency and accuracy of real estate are improved, so that the new method of real estate is provided by the system.

关键词： BP neural network GIS hedonic price real estate appraisal

Convergence of the Vlasov-Poisson-Fokker-Planck system to the incompressible Euler equations

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science china Mathematics 2006年第2期49卷 255-266页

作者： xiao Ling, LI Fucai & WANG Shu Academy of Mathematics and Systems science, Chinese Academy of sciences, beijing 100080, china Department of Mathematics, Nanjing university, Nanjing 2.0093, china College of applied sciences, beijing university of technology, beijing 10002., china Academy of Mathematics and Systems science Chinese Academy of Sciences Beijing China Department of Mathematics Nanjing University Nanjing China College of applied sciences Beijing University of Technology Beijing China

We establish the convergence of the Vlasov-Poisson-Fokker-Planck system to the incompressible Euler equations in this paper. The convergence is rigorously proved on the time interval where the smooth solution to the incompressible Euler equations exists. The proof relies on the compactness argument and the so-called relative-entropy method.

关键词： Vlasov-Poisson-Fokker-Planck system incompressible Euler equations relative-entropy method.

Establishment of liver specific glucokinase gene knockout mice: a new animal model for screening anti-diabetic drugs

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Acta Pharmacologica Sinica 2004年第12期25卷 93-99页

作者： Ya-li ZHANG, xiao-hong TAN2. Mei-fang xiao, Hui LI, Yi-qing Mao, xiao YANG2. Huan-ran TAN3 Department of Pharmacology, School of Basic Medical science, Peking university Health science Center, beijing 100083 2.nstitute of Biotechnology Academy ofMilitary Medical science, beijing 100071, china Department of Pharmacology School of Basic Medical Science Peking University Health Science Center 北京 100083 Institute of Biotechnology Academy of Military Medical science 北京 100071

AIM: To characterize the liver-specific role of glucokinase in maintaining glucose homeostasis and to create an animal model for diabetes. METHODS: We performed hepatocyte-specific gene knockout of glucokinase in mice using Cre-loxP gene targeting strategy. First, two directly repeated loxP sequences were inserted to flank the exon 9 and exon 10 of glucokinase in genomic DNA. To achieve this, linearized targeting vector was electroporated into ES cells. Then G418- and Gancyclovir-double-resistant clones were picked and screened by PCR analysis and the positives identified by PCR were confirmed by Southern blot. A targeted clone was selected for microinjection into C57BL/6J blastocysts and implanted into pseudopregnant FVB recipient. Chimeric mice and their offspring were analyzed by Southern blot. Then by intercrossing the Alb-Cre transgenic mice with mice containing a conditional gk allele, we obtained mice with liver-specific glucokinase gene knockout. RESULTS: Among 161 double resistant clones 4 were positive to PCR and Southern blot and only one was used for further experiments. Eventually we generated the liver specific glucokinase knockout mice. These mice showed increased glucose level with age and at the age of 6 weeks fasting blood glucose level was significantly higher than control and they also displayed impaired glucose tolerance. CONCLUSION: Our studies indicate that hepatic glucokinase plays an important role in glucose homeostasis and its deficiencies contribute to the development of diabetes. The liver glucokinase knock- out mouse is an ideal animal model for MODY2. and it also can be applied for screening anti-diabetic drugs.

关键词： animal disease model non insulin dependent diabetes mellitus type 2.diabetes mellitus glucokinase knockout mice

A New Chirality Invertible Photoswitch:Light-Driven Axially Chiral Hydrazone Enabling Dynamic Handedness Inversion of Self-Organized Helical Superstructure

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CCS Chemistry 2024年第8期6卷 2011-2020页

作者： Ruochen Lan Jinying Bao Zhaozhong Li Zizheng Wang Zichen Wang Qian Wang Lanying Zhang jiumei xiao Huai Yang Institute of Advanced Materials College of Chemistry and Chemical EngineeringJiangxi Normal UniversityNanchang 330022 beijing Advanced Innovation Center for Materials Genome Engineering School of Materials Science and EngineeringPeking UniversityBeijing 100871 School of Materials science and Engineering University of Science and Technology BeijingBeijing 100083 beijing Advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing 100083 Key Laboratory of Polymer Chemistry and Physics of Ministry of Education Peking UniversityBeijing 100871 School of Mathematics and Physics University of Science and Technology BeijingBeijing 100083

Inspired by nature,dynamic self-organized helical superstructures are becoming attractive as building blocks in soft photonic crystals and advanced chiroptical ***,a chirality invertible hydrazone photoswitch,possessing high helical twisting power(HTP)was judiciously designed and *** to the photoinduced configuration changes of the hydrazone photoswitch,it displayed superior thermal stability and strikingly reversible HTP *** incorporating a novel chiral hydrazone(CH)into the liquid crystal(LC)host,a handedness invertible cholesteric liquid crystal(CLC)helical superstructure with high thermal stability and light-modulated photonic bandgap was *** inferred that the mechanism of chirality inversion of the novel CH photoswitch derived from changes in the dihedral angle between the two naphthalene rings induced by hydrazone ***,the influence of chemical structures on its photoresponsiveness was ***,the potential applications of this advanced light-driven CLC in soft photonic crystals,showing erasable and rewritable colorful patterns and chiroptical templates to induce handedness invertible circularly polarized luminescence were illustrated.

关键词： chirality inversion hydrazone photoswitch cholesteric liquid crystals dynamic photonic crystals dynamic circularly polarized luminescence

Latest progress on interactions between VLF/ELF waves and energetic electrons in the inner magnetosphere

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science china Earth sciences 2010年第3期53卷 317-326页

作者： xiao FuLiang1,2. ZONG QiuGang3, SU ZhenPeng4, TIAN Tian3 & ZHENG HuiNan4 1 School of Physics and Electronic sciences, Changsha {2. of science and technology, Changsha 410004, china 2.State Key Laboratory of Space Weather, Chinese Academy of sciences, beijing 100190, china 3 Institute of Space Physics and applied technology, Peking {2., beijing 100871, china 4 CAS Key Lab for Basic Plasma science, School of Earth and Space sciences, {2. of science and technology of china, Hefei 2.002., china School of Physics and Electronic sciences Changsha University of Science and Technology Changsha China State Key Laboratory of Space Weather Chinese Academy of Sciences Beijing China Institute of Space Physics and applied technology Peking University Beijing China CAS Key Lab for Basic Plasma science School of Earth and Space Sciences University of Science and Technology of China Hefei China

Interactions between very/extremely low frequency (VLF/ELF) waves and energetic electrons play a fundamental role in dynamics occurring in the inner magnetosphere. Here, we briefly discuss global properties of VLF/ELF waves, along with the variability of the electron radiation belts associated with wave-particle interactions and radial diffusion. We provide cases of electron loss and acceleration as a result of wave-particle interactions primarily due to such waves, and particularly some preliminary results of 3D evolution of phase space density from our currently developing 3D code. We comment on the existing mechanisms responsible for acceleration and loss, and identify several critical issues that need to be addressed. We review latest progress and suggest open questions for future investigation.

关键词： wave-particle interaction VLF/ELF waves energetic electrons acceleration and loss inner magnetosphere

Spectrum characteristics and pump wavelengths of Nd_(3+) -doped double-clad fiber

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Chinese science Bulletin 1997年第11期42卷 897-900页

作者： MING Hai, YANG Bao, DONG xiaopeng, A. Fedotov, Xudong xiao and M. M. T. Loy1. Department of Physics, {2. of science and technology of china, Hefei 2.002., china 2. Department of Physics, {2. of science and technology of Hong Kong, Hong Kong, china Department of Physics University of Science and Technology of China Hefei China Department of Physics University of Science and Technology of Hong Kong Hong Kong China

Nd3+ -doped double-clad fiber is a new type of fiber that has large *** large receivingarea compared with single-clad rare-earth-doped *** Nd3+-doped double-clad fiberpumped directly by laser-diode arrays can be manufactured into high-power fiber lasers,high-power superfluorescence sources and high-gain fiber amplifiers,and they will be applied

关键词： double-clad fiber optimum pump wavelength optical spectrum.