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Structure heterogeneity in Metallic Glass: Modeling and Experiment

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Journal of Materials Science & Technology 2014年第6期30卷 560-565页

作者： h.B.ke J.F.Zeng C.T.Liu Y.Yang Centre for Advanced Structural Materials Department of Mechanical and Biomedical EngineeringCity University of Hong Kong

Despite the great efforts dedicated to metallic glasses （MGs）, their structure still remains a mystery to be understood. With comparison to the existing mJciomechanical models, such as the free-volume and shear transformation zone （STZ） models, we first discuss in this article our recently proposed ＇core-shell＇ model, which contains a solid-like matrix and liquid-like inclusions. This serves as the theoretical basis to understand the structural heterogeneity in MGs in our analytical framework. After that, a scanning ultrafast nanoindentation technique is used to map out the structure heterogeneity in a Zr-based bulk metallic glass （BMG）. With these ongoing research efforts, we hope that more research work could be stimulated in the pursuit of the structure-property relation in MGs.

关键词： Metallic glass Structure heterogeneity Nanoindentation Core-shell model

Effect of corrosion product films on the in vitro degradation behavior of Mg-3%Al-1%Zn(in wt%) alloy in hank's solution

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Journal of Materials Science & Technology 2018年第10期34卷 1756-1764页

作者： B.J.Wang D.K.Xu J.h.Dong W.ke School of Environmental and Chemical Engineering Shenyang Ligong University CAS key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal Research Chinese Academy of Sciences Environmental Corrosion Center Institute of Metal Research Chinese Academy of Sciences

Through investigating the corrosion behavior of an as-extruded Mg-3wt%gAl-lwt%Zn （AZ31） alloy in a simulated physiological fluid of hank＇s solution, it demonstrates that the corrosion process was depen- dent on the immersion time. Further analyses revealed that the highest corrosion resistance could be obtained at 24 h due to the formation of a compact layer of corrosion products on the sample surface. With increasing the immersion time to up to 48 h, the thickness of surface films increased gradually but obvious de-bonding of such film from the substrate could take place, resulting in a certain resilience of the overall corrosion resistance.

关键词： Magnesium Surface layer Corrosion product Interface

Nitrogen Cycling and Losses Under Rice-Wheat Rotations with Coated Urea and Urea in the Taihu Lake Region

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Pedosphere 2007年第1期17卷 62-69页

作者： WANG Xiao-Zhi ZhU Jian-Guo GAO Ren h. YASUKAZU FENG ke State key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Nanjing 210008 （China） Environment Science and Engineering College Yangzhou University Yangzhou 225009 （China） Fujian Normal University Fuzhou 350007 （China） Japan International Research Center for Agricultural Sciences 1-2 Ohwashi Tsukuba Ibaraki 305-8686 （Japan）

A lysimeter experiment with undisturbed soil profiles was carried out to study nitrogen cycling and losses in a paddy soll with applications of coated urea and urea under a rice-wheat rotation system in the Taihu Lake region from 2001 to 2003. Treatments for rice and wheat included urea at conventional, 300 （rice） and 250 （wheat） kg N ha^-1, and reduced levels, 150 （rice） and 125 （wheat） kg N ha^-1, coated urea at two levels, 100 （rice） and 75 （wheat） kg N ha^-1, and 150 （rice） and 125 （wheat） kg N ha^-1, and a control with no nitrogen arranged in a completely randomized design. The results under two rice-wheat rotations showed that N losses through both Nh3 volatilization and runoff in the coated urea treatments were much lower than those in the urea treatments. In the urea treatments N runoff losses were significantly （P 〈 0.001） positively correlated （r = 0.851） with applied N. N concentration in surface water increased rapidly to maximum two days after urea application and then decreased quickly. however, if there was no heavy rain within five days of fertilizer application, the likelihood of N loss by runoff was not high. As the treatments showed little difference in N loss via percolation, nitrate N in the groundwater of the paddy fields was not directly related to N leaching. The total yield of the two rice-wheat rotations in the treatment of coated urea at 50% conventional level was higher than that in the treatment of urea at the conventional level. Thus, coated urea was more favorable to rice production and environmental protection than urea.

关键词： ammonia volatilization coated urea N cycling percolation runoff

A Remark on Partly Dissipative Reaction Diffusion Systems on IR^n

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Acta Mathematicae Applicatae Sinica 2008年第4期24卷 583-588页

作者： Xue-ke Pu College of Maths and Physics Chongqing University Chongqing 400044 China The Graduate School of China Academy of Engineering Physics P.O. Box 2101 Beijing 100088 China Institute of Fundamental Sciences Massey University New Zealand

The long time behavior of the solutions of some partly dissipative reaction diffusion systems is studied. We prove the existence of a compact （L^2 × L^2 - h^1 × L^2） attractor for a partly dissipative reaction diffusion system in Rn. This improves a previous result obtained by A. Rodrigues-Bernal and B. Wang concerning the existence of a compact （L^2 × L^2 - L^2 × L^2） attractor for the same system.

关键词： Reaction diffusion equation attractor asymptotic compactness

Structure of high Temperature Phase α-Ba_3Y(BO_3)_3 Crystal

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Chinese Journal of Structural Chemistry 2003年第5期22卷 550-552页

作者： PANShang-ke WANGGuo-Fu StatekeyLaboratoryofStructuralChemistry FujianInstituteofResearchontheStructureofMatterTheChineseAcademyofSciencesFuzhouFujian350002China GraduateSchooloftheChineseAcademyofSciences Beijing100039China

The high temperature phase a-Ba3Y(BO3)3 was synthesized by Czochralski method, and its crystal structure has been determined by single-crystal X-ray diffraction. It crystallizes in the trigonal system, space group 3R with a = 13.028(2), c = 9.4992(2) ? V = 1396.1(5) ?, Ba3YB3O9, Mr = 677.36, Z = 6, Dc = 4.834 g/cm3, l(MoKa) = 0.71073 ? m = 18.721 mm-1, F(000) = 1764, the final R = 0.0718 and wR = 0.1640 for 1199 observed reflections with I > 2s(I). In this structure two alternate nonequivalent Y atoms form one-dimensional chains bridged by the Ba atoms with BO3 triangles which link Y(1) and Y(2), respectively. The Ba atom is surrounded by nine O atoms belonging to six BO3 triangles.

关键词： synthesis crystal structure double borate

Trans-scale mechanics: looking for the missing links between continuum and micro/nanoscopic reality

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Acta Mechanica Sinica 2008年第2期24卷 111-126页

作者： Y.L.Bai h.Y.Wang M.F.Xia F.J.ke State key Laboratory of Non-linear Mechanics (LNM) Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China State key Laboratory of Non-linear Mechanics (LNM) Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Department of Physics Peking University Beijing 100871 China State key Laboratory of Non-linear Mechanics (LNM) Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Department of Applied Physics Beihang University Beijing 100083 China

Problems involving coupled multiple space and time scales offer a real challenge for conventional frame-works of either particle or continuum mechanics. In this paper, four cases studies （shear band formation in bulk metallic glasses, spallation resulting from stress wave, interaction between a probe tip and sample, the simulation of nanoindentation with molecular statistical thermodynamics） are provided to illustrate the three levels of trans-scale problems （problems due to various physical mechanisms at macro-level, problems due to micro-structural evolution at macro/micro-level, problems due to the coupling of atoms/ molecules and a finite size body at micro/nano-level） and their formulations. Accordingly, non-equilibrium statistical mechanics, coupled trans-scale equations and simultaneous solutions, and trans-scale algorithms based on atomic/molecular interaction are suggested as the three possible modes of trans-scale mechanics.

关键词： Multi-scale Missing-links Continuum mechanics Particle mechanics Trans-scale mechanics

Catalytic hydrogenation of Methanol-Containing Effluent from Epoxidation of Propylene

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China Petroleum Processing & Petrochemical Technology 2015年第3期17卷 94-101页

作者： Cheng ke SINOPEC Luoyang Petrochemical Complex

This paper describes the hydrogenation of impurities in the methanol-containing effluent from the propylene epoxidation process with hydrogen peroxide. The effects of reaction temperature, pressure, weight hourly space velocity(WhSV) and h2/methanol ratio on the concentration of various impurities in methanol solvent were investigated. It was found out that the aldehyde, hydrogen peroxide and nitro compounds in the methanol solvent could be completely hydrogenated over the Ni catalyst under proper reaction conditions. 90% of acetone and up to 50% of acetals(ketals) existing in the methanol solvent could be hydrogenated. No significant change was observed for the rest of the impurities that were present in the methanol solvent(i. e., 1-methoxy-2-propanol, 2-methoxy-1-propanol and 1,2-propanediol). The h2O2 decomposition reaction was enhanced using Ni catalyst, through the formation of NioOh, but no oxygen was found in the off-gas of hydrogenation reaction since Nioh could react on NioOh formed via dissociative adsorption of hydrogen peroxide, or on NioO formed via adsorption of oxygen.

关键词： propylene epoxidation methanol hydrogenation

An Immersed Boundary-Lattice Boltzmann Prediction for Particle hydrodynamic Focusing in Annular Microchannels

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Chinese Physics Letters 2018年第10期35卷 89-92页

作者： Tao h Meng-Dan hU Si-si Zhou Dong-ke SUN School of Mechanical Engineering Southeast UniversityNanjing 211189 School of Materials Science and Engineering Southeast UniversityNanjing 211189 School of Chemistry and Chemical Engineering Southeast UniversityNanjing 211189

We numerically study the dynamics of particle crystals in annular microchannels by the immersed-boundary（IB）lattice Boltzmann（LB） coupled model, analyze the fluid-particle interactions during the migration of particles,and reveal the underlying mechanism of a particle focusing on the presence of fluid flows. The results show that the Reynolds and Dean numbers are key factors influencing the hydrodynamics of particles. The particles migrate onto their equilibrium tracks by adjusting the Reynolds and Dean numbers. Elliptical tracks of particles during hydrodynamic focusing can be predicted by the IB-LB model. Both the small Dean number and the small particle can lead to a small size of the focusing track. This work would possibly facilitate the utilization of annular microchannel flows to obtain microfluidic flowing crystals for advanced applications in biomedicine and materials synthesis.

关键词： An Immersed Boundary-Lattice Boltzmann Prediction for Particle hydrodynamic Focusing in Annular Microchannels

A Novel Video Reversible Data hiding Algorithm Using Motion Vector for h.264/AVC

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Tsinghua Science and Technology 2017年第5期22卷 489-498页

作者： ke Niu Xiaoyuan Yang Yingnan Zhang key Laboratory of Network & Information Security of PAP Engineering College of PAP

A novel reversible data hiding algorithm for h.264/AVC videos is proposed. histogram Shifting （hS） of motion vector values is used efficiently in reversible data hiding to embed data. By designating a specific decoded reference frame, the distortion accumulation effects due to modification of the motion vectors is overcome. All the extracted information can be recovered without loss of the original compressed video carrier. The experimental results show that the proposed algorithm is simple, has higher capacity and invisibility than other existing schemes, and can adjust the relationship between capacity and invisibility according to embedded load.

关键词： reversible video data hiding h.264/AVC motion vector histogram modification modified referenceframe