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Study on Tribological properties of Irradiated Crosslinking UHMWpE Nano-Composite

Journal of Bionic Engineering 2009年第1期6卷 7-13页

作者： Lei Xiong, Dang-sheng Xiong, Jia-bo JinDepartment of Materials science and Engineering, nanjing university of science and technology, nanjing 210094, p. r. china [a]Department of Materials science and Engineering Nanjing University of Science and Technology Nanjing 210094 P. R. China

Ultra High Molecular Weight polyethylene(UHMWpE)has been widely used as a bearing material for artificial joint replacement over forty *** is usually crosslinked by gamma rays irradiation before its implantation into human *** this study,UHMWpE and UHMWpE/nano-hydroxyapatite(n-HA)composite were prepared by vacuum hot-pressing *** prepared materials were irradiated by gamma rays in vacuum and molten heat treated in vacuum just after *** effect of filling n-HA with gamma irradiation on tribological properties of UHMWpE was investigated by using friction and wear experimental machine(model MM-200)under deionized water ***-morphology of worn surface was observed by metallographic *** angle and hardness of the materials were also *** results show that contact angle and hardness are changed by filling n-HA and gamma *** coefficient and wear rate under deionized water lubrication are reduced by filling *** friction coefficient is increased and wear rate is reduced significantly by gamma *** worn surface of unfilled material is mainly characterized as adhesive wear and abrasive wear,and that of n-HA filled material is mainly characterized as abrasive *** gamma irradiation,the degrees of adhesive and abrasive wear for unfilled material and abrasive wear of n-HA filled material are significantly *** and filled materials after irradiation are mainly shown as slight fatigue *** results indicate that UHMWpE and UHMWpE/n-HA irradiated at the dose of 150 kGy can be used as bearing materials in artificial joints for its excellent wear resistance compared to original UHMWpE.

关键词： tribological properties irradiated crosslinking UHMWpE n-HA artificial joints

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A method of constructing a database-free optimal dynamical system and a global optimal dynamical system

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science china(physics,Mechanics & Astronomy) 2008年第7期51卷 905-915页

作者： WU ChuiJie1? & WANG Liang2 1 State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian university of technology, Dalian 116024, china 2 research Center for Fluid Dynamics, School of science, pla university of science and technology, nanjing 211101, china 1. State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 China 2. research Center for Fluid Dynamics School of Science PLA University of Science and Technology Nanjing 211101 China

In this paper, to overcome the drawbacks of pOT which minimize the reminder, not only the optimal functional with minimal residual is put forward, but also the method of global optimization is used. Under the condition of large reminder, the optimal bases can also be obtained through the method of pOTres without the approaching of initial conditions. In addition, compared with local optimization, the advantage of global optimization is remarkable. On the one hand, we can expect that the dynamical system based on the global optimal bases will include more information than the ones based on the local optimal bases, since the global optimal bases are much more precise than the local optimal bases. On the other hand, from the point of view of error, the global optimal bases are independent of the choice of the object functional and the initial bases.

关键词： dynamical system residual global optimization

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Latent ancestral graph of structure vector autoregressive models

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Journal of Systems Engineering and Electronics 2010年第2期21卷 233-238页

作者： Wei Gao1,2and Zheng Tian2,3 1.School of Statistics,Xi’an university of Finance&Economics,Xi’an 710061,p.r.china 2.Department of Applied Mathematics,Northwestern polytechnical university,Xi’an 710072,p.r.china 3.State Key Laboratory of remote Sensing science,institute of remote Sensing Applications,Chinese Academy of sciences,Beijing 100101,p.r.china School of Statistics Xi'an University of Finance & EconomicsXi'an 710061P.R.China Department of Applied Mathematics Northwestern Polytechnical UniversityXi'an 710072P.R.China Department of Applied Mathematics Northwestern Polytechnical UniversityXi'an 710072P.R.China State Key Laboratory of remote Sensing science Institute of Remote Sensing ApplicationsChinese Academy of SciencesBeijing 100101P.R.China

A class of latent ancestral graph for modelling the dependence structure of structural vector autoregressive （VAr） model affected by latent variables is proposed. The graphs are mixed graphs with possibly two kind of edges, namely directed and bidirected edges. The vertex set denotes random variables at dif- ferent times. In Gaussian case, the latent ancestral graph leads to a simple parameterization model. A modified iterative conditional fitting algorithm is presented to obtain maximum likelihood esti- mation of the parameters. Furthermore, a log-likelihood criterion is used to select the most appropriate models. Simulations are performed using illustrative examples and results are provided to demonstrate the validity of the methods.

关键词： multivariate time series latent ancestral graph itera- tive conditional fitting.

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Wavelet estimation of the diffusion coefficient in time dependent diffusion models

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science china Mathematics 2007年第11期50卷 1597-1610页

作者： ping CHEN~(1,2+) Jin-de WANG~1 1 Department of Mathematics,nanjing university,nanjing 210093,china 2 School of science,nanjing university of science and technology,nanjing 210094,china Department of Mathematics Nanjing University Nanjing 210093 China School of science Nanjing University of Science technology Nanjing 210094 China

The estimation problem for diffusion coefficients in diffusion processes has been studied in many papers,where the diffusion coefficient function is assumed to be a 1-dimensional bounded Lipschitzian function of the state or the time *** is no previous work for the nonparametric estimation of time-dependent diffusion models where the diffusion coefficient depends on both the state and the *** paper introduces and studies a wavelet estimation of the time-dependent diffusion coefficient under a more general assumption that the diffusion coefficient is a linear growth Lipschitz *** the properties of martingale,we translate the problems in diffusion into the nonparametric regression setting and give the Lr convergence rate.A strong consistency of the estimate is *** this result one can estimate the time-dependent diffusion coefficient using the same structure of the wavelet estimators under any equivalent probability *** example,in finance,the wavelet estimator is strongly consistent under the market probability measure as well as the risk neutral probability measure.

关键词： wavelet estimation time-dependent diffusion coefficient linear growth condition strong consistency

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Effect of Excipients on Stability and Structure of rhCuZn-SOD Encapsulated in pLGA Microspheres

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Chemical research in Chinese Universities 2004年第3期20卷 323-327页

作者： LIU Ling 1,2 ,GE Yu 1 and YUAN Qin-sheng 1 1. State Key Laboratory of Bioreactor Engineering and institute of Biochemistry,East china university of science and technology,Shanghai 200237,p. r. china 2. public Health School,nanjing Medical university,nanjing 210029,p. r. china E china Univ Sci & Technol State Key Lab Bioreactor Engn Shanghai 200237 Peoples R China E china Univ Sci & Technol Inst Biochem Shanghai 200237 Peoples R China nanjing Med Univ Sch Publ Hlth Nanjing 210029 Peoples R China

When a protein is encapsulated into poly( DL -lactide-co-glycolide)(pLGA) microspheres by means of the double-emulsion method,the harsh microspheres formation process including ultrasonification,exposure to an organic solvent and a polymer may cause the denaturation of the protein. In this study,we investigated the enzymatic activity change and the effect of the excipients on the stability of recombinant human Cu,Zn-superoxide dismutase(rhCu,Zn-SOD) during the emulsification. The specific activity recovery was found to be concentration dependent and the excipients involved such as pEG 600 and Tween 20,and trehalose were shown to increase the stability of rhCu,Zn-SOD. The protein structural integrity within the microspheres was analyzed by FTIr. The structure of rhCu,Zn-SOD within pLGA microspheres containing trehalose was found to be similar to that of the native solid state,whereas the protein encapsulated during the preparation in the absence of any excipient changed due to the possible hydrophobic interaction with the polymer. The results suggest that a rational stability strategy for protein to be encapsulated into microspheres should aim at different processes.

关键词： poly( DL -lactide-co-glycolide)(pLGA) microsphere recombinant human Cu Zn-superoxide dismutase(rhCu Zn-SOD) Fourier transform infrared(FTIr) spectroscopy protein stability Excipient

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ENVIrONMENTAL AND TOpOGrApHIC INFLUENCES ON ATMOSpHErIC INTErNAL SHIp WAVES

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Journal of Hydrodynamics 2008年第4期20卷 440-447页

作者： ZANG Zeng-liang pAN Xiao-bin ZHANG Ming Department of Martial Meteorology Institute of Meteorology PLA University of Science and TechnologyNanjing 211101 China State Key Laboratory of Atmospheric sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

A theoretical model was used to investigate the influences of environmental and topographic parameters on the atmospheric three-layer internal ship waves. The results show that both the wavelength and the wedge angle decrease with an increase in the Scorer parameter, and the rate of changes in the wavelength and wedge angle are also alike. The results also show that the wedge angle decreases with an increase in the width of mountain, but the wavelength varies little with it. It is suggested that the wedge angle is determined by the ratio of the wavelength to the scale of the mountain. Besides, numerical sensitivity experiments were performed to test the former numerical experiments. The simulated results are consistent with the analytical results.

关键词： Scorer parameter topographic parameter atmospheric internal ship waves numerical simulation

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An adaptive version of ghost-cell immersed boundary method for incompressible flows with complex stationary and moving boundaries

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science china(physics,Mechanics & Astronomy) 2010年第5期53卷 923-932页

作者： WANG Liang1 & WU ChuiJie2,3 1 School of science,pla university of science and technology,nanjing 211101,china 2 State Key Laboratory of Structural Analysis for Industrial Equipment,Dalian university of technology,Dalian 116024,china 3 School of Aeronautics and Astronautics,Dalian university of technology,Dalian 116024,china 1. School of science PLA University of Science and Technology Nanjing 211101 China2. State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 China3. School of Aeronautics and Astronautics Dalian University of Technology Dalian 116024 China

An adaptive version of immersed boundary method for simulating flows with complex stationary and moving boundaries is *** method employs a ghost-cell methodology which allows for a sharp representation of the immersed *** simplify the implementation of the methodology,a volume-of-fluid method is introduced to identify the immersed *** addition,the domain is spatially discretized using a tree-based discretization which is relatively simple to implement a fully flexible adaptive refinement ***,the methodology is validated by comparing it with numerical and experimental results on three cases:(1) the flow passing a circular cylinder at re=40 and re=100,(2) a periodic oscillation of a circular cylinder in fluid at rest and(3) the self-propelled fish-like swimming at re=6400.

关键词： adaptive mesh refinement ghost-cell immersed boundary method moving boundaries

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On Doubly Degenerate Quasilinear parabolic Equations of Higher Order

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Acta Mathematica Sinica,English Series 2005年第1期21卷 197-208页

作者： Zhen Hai LIU Department of Mathematics,Changsha university of science and technology Changsha 410077,p.r.china Department of Mathematics Changsha University of Science and Technology Changsha 410077 P. R. China

We deal with the existence of periodic solutions for doubly degenerate quasilinear parabolic equations of higher order,which can degenerate,on a part of the boundary,on a segment in the interior of the domain and in t... 详细信息

关键词： Double degeneration Quasilinear parabolic equations periodic solutions

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Influences of low-Ti substitution for La and Mg on the electrochemical and kinetic characteristics of AB_3-type hydrogen storage alloy electrodes

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science china(Technological sciences) 2010年第1期53卷 242-247页

作者： DONG ZhenWei1,2,WU YaoMing1,MA LiQun2,SHEN XiaoDong2 & WANG LiMin1 1 State Key Laboratory of rare Earth resource Utilization,Changchun institute of Applied Chemistry,Chinese Academy of sciences,C hangchun 130022,china 2 College of Material science and Engineering,nanjing university of technology,nanjing 210009,china 1. State Key Laboratory of rare Earth resource Utilization Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 China2. College of Material Science and Engineering Nanjing University of Technology Nanjing 210009 China

The(La0.67Mg0.33)1-xTixNi2.75Co0.25(x = 0,0.05,0.10,0.15 and 0.20,at%) alloys were synthesized by arc melting and subsequent heat solid-liquid diffusing *** structure,electrochemical properties and kinetic characteristics of the alloys were investigated *** results showed that all the alloys mainly consisted of the(La,Mg)Ni3,LaNi5 phases,and the lattice parameters and the cell volumes of the(La,Mg)Ni3 and LaNi5 phases decreased with increasing Ti *** alloy electrodes could be activated to reach their maximum discharge capacity within five *** cycle life after 100 charge/discharge cycles(C100/Cmax) and the high-rate dischargeability at a discharge current density of 1200 mA/g first increased and then *** the results showed that low-Ti content in AB3-type hydrogen storage alloys was beneficial to improvements of the overall electrochemical properties,and the optimum overall electrochemical performance of the alloy electrodes was obtained when x = 0.05.

关键词： AB3-type alloy metal hydride electrode microstructure electrochemical property kinetic characteristic

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The Synthetic Evaluation of Warhead Overall Efficiency

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Journal of Systems Engineering and Electronics 2003年第1期14卷 12-17页

作者： Gu Xiaohui & Cao Bing College of Mechanics, nanjing university of science & technology, nanjing 210094, p. r. china College of Mechanics Nanjing University of Science & Technology Nanjmg 210094 P. R. China

The evaluation system of smart ammunition warhead overall efficiency has been established in this paper. Allkinds of evaluation methods have been analyzed. Having led the concept of hierarchical structure into technique for orderpreference by similarity to ideal solution (TOpSIS) method, we put forward the step TOpSIS method which is suitable forevaluating the overall efficiency of smart ammunition warheads. In the calculation of index weight, the graded weight cal-culus is put forward which hardly relies on the subjectivity of decision-makers and can reflect the sensitivity and compatibili-ty of the index. In the graded weight calculation, the proportional-arithmetic weight value calculus and sensitivity-compati-bility weight value calculus are given respectively.

关键词： Step analysis TOpSIS method Warhead Efficiency evaluation.

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