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Tuning periodicity.of poly.er-decorated carbon nanotubes

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Science China Chemistry 2012年第5期55卷 802-807页

作者： LAIRD Eric D. li Christopher y. A. J. Drexel Nanotechnology.Institute and Department of Materials Science and Engineering Drexel University Philadelphia Pennsylvania 19104 USA

Carbon nanotube (CNT) is one of the most extensively.investigated nanomaterials. Patterning soft matter such as liquid cry.tals and poly.ers on CNTs could potentially.enable various applications for CNTs. We have demonstrated that controlled poly.er cry.tallization using CNTs as the 1D nucleation sites can lead to periodically.functionalized CNTs. Here we show that selected cry.talline block copoly.ers can be periodically.decorated along CNTs. This facile technique opens a gateway.to periodic patterning on 1-D nanomaterials.

关键词： poly.er cry.tallization carbon nanotube block copoly.ers

NUCLEATION OF RARE EARTH-RICH PHASE PARTICLES IN Ti-5Al-4Sn-2Zr-1Mo-0.25Si-1Nd ALLOy

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Acta Metallurgica Sinica(English Letters) 1998年第4期11卷 265-269页

作者： G.P.li D.li and y. y. liu (Department of Titanium Alloy., Institute of Metal Research, The Chinese Academy.of Sciences, Sheny.ng 110015, China) Inst of Metal Research The Chinese Acad of Sciences Shenyang China

High resolution electron microscopy.studies of rure earth-rich phase particles in a melt-quenched Ti-5Al-4Sn-2Zr-1MO-0.25Si-1Nd alloy.indicate that the α-Ti matrix cry.tallizes prior to the rare earth-rich phase particles. According to a new nucleation model, the heteropeneous nucleation of the rare earth-rich phase particles at the matrix interface is easier than the homogeneous nucleation off the interface matrix, which is consistent with the results of the HREM obseroations.

关键词： Ti alloy rure earth rich phase nucleation

Investigation of the crack problem in non-local piezoelectric materials under combined electromechanical loadings

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Acta Mechanica Sinica 2009年第2期25卷 219-225页

作者： Q. li y. Chen School of Aerospace, Xi’an Jiao-Tong University.710049 Xi’an, China School of Aerospace Xi’an Jiao-Tong University 710049 Xi’an China

The present investigation of the crack problem in piezoelectric materials is performed based on the non-local theory. After some manipulations, the impermeable crack, the permeable crack （the crack gap is full of NaCI solution）, and the semi-permeable crack （the crack gap is full of air or silicon oil） are reduced to a uniform formulation by.assuming the normal electric displacement on the crack surfaces to be an unknown variable. Thus, a triple integral equation with the unknown normal electric displacement is established. By.using the Newton iterative method and solving the triple integral equation, it is found that the normal electric displacement on the crack surfaces is no longer a constant as determined by.previous studies, rather, it depends upon the remote combined electromechanical loadings. Numerical results of the stresses and electric displacement fields show that there are no singularities at the crack tips so that the stresses remain finite. It is of great significance that the concrete electric boundary.condition on the crack surfaces exerts significant influence on the near-tip fields and in this way.play. an important role in evaluating the crack stability.in the non-local piezoelectric materials. More specifically. the impermeable crack model alway. overestimates the finite stresses at the crack tips, whereas the permeable crack model alway. underestimates them.

关键词： Crack Non-local piezoelectric materialsImpermeable Permeable Semi-permeable

STUDIES OF LOW-CONCENTRATION CHROMATE PASSIVE FILM FOR ZINC-BASED ALLOy.COATED STEEL WIRES

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Acta Metallurgica Sinica(English Letters) 1999年第5期12卷 736-738页

作者： li, y. Wang, H.R. Feng, F.L. Wei, X.J. Northeastern Univ Shenyang China

The corrosion resistance of a low concentration chromate passive film for zinc based alloy.coated steel wires was assessed by.salt spray.and electrochemical corrosion tests. XPS and AES analy.es showed that the comp... 详细信息

关键词： chromate passive film zinc based alloy.coating XPS AES

Simulation of the Influence of Surface Wettability.on Viscous Fingering Phenomenon in Porous Media

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Journal of Bionic Engineering 2010年第3期7卷 267-275页

作者： B. Dong~1, y. y. y.n~2, W. Z. li~1, y. C. Song~1 1. Key.Laboratory.of Ocean Energy.Utilization and Energy.Conservation (Ministry.of Education, China), Dalian University.of Technology. Dalian 116024, P. R. China 2. Faculty.of Engineering, University.of Nottingham, University.Park, NG7 2RD, UK [a] Key.Laboratory.of Ocean Energy.Utilization Energy.Conservation (Ministry.of Education China) Dalian University of Technology Dalian 116024 P. R. China [b] Faculty of Engineering University of Nottingham University Park NG7 2RD UK

Fingering phenomena are common occurrence in the natural world. It generally.takes place when a less viscous fluid displacesa more viscous fluid ty.ically.in porous media. Nowaday., such phenomena have extensively.been studied due to itsimportance in many.industrial fields. In this paper, the effects of surface wettability.on finger pattern are studied and simulatednumerically.by.the Lattice Boltzmann method (LBM). The displacement efficiency.is investigated by.using two parameters,namely. the breakthrough time and the areal sweep efficiency. The simulation has demonstrated that surface wettability.willinfluence the finger pattern no matter the gravity.is considered or not, but in the presence of gravity. the finger pattern is muchmore complicated and irregular due to the coexistence and competition of capillary.force, viscous force and gravity.

关键词： immiscible fluids porous media viscous fingering wettability

NUMERICAL SIMULATION OF MOLTEN POOL AND CONTROL STRATEGy.OF KISS POINT IN A TWIN-ROLL STRIP CASTING PROCESS

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Acta Metallurgica Sinica(English Letters) 2008年第6期21卷 459-468页

作者： G.M. Cao C.G. li Z. y. liu D. Wu G.D. Wang X.H. liu State Key.Laboratory.of Rolling ＆ Automation Northeastern University Shenyang 110004 China

Coupled turbulent flow, temperature fields of the twin-roll casting strip process were simulated by.three-dimensional finite element method. Based on the heat balance calculation and using inverse methods between the simulations and real experiments, the relational models among casting speed, location, and coefficient of heat transfer between molten metal and rolls in different regions are given. In the simulation, the calculated surface temperatures are in good agreement with the measured values. An on-line model of kiss point is derived by.simulations and the geometry.of molten pool, corresponding control strategy.is also proposed.

关键词： Twin-roll strip casting Coupled temperature and flow field Numerical simulation Kiss point Control strategy

Efficient Sy.thesis of Optically.Active Alcohols

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复旦学报（自然科学版） 2005年第5期44卷 672-673页

作者： J.S. Chen Z.R. Dong y.y. li B.Z. li y. Xing W.y. Shen G. Chen X.Q. Zhang J.X. Gao State Key.Laboratory.of Phy.ical Chemistry.of Solid Surfaces Deparment of ChemistryXiamen University Xiamen 361005 China

Optically.active secondary.alcohols are versatile building blocks for sy.thesis of unnatural biological active compounds and functional materials. Therefore, study.on efficient sy.thesis of optically.active alcohols is becoming an important subject in sy.thetic organic chemistry. Cataly.ic asy.metric reduction of carbony. compounds is a practical method to create chiral alcohols. For the past decades, a large number of cataly.ic methods have been developed to achieve this goal.

关键词：配合基酒精乙醇生物学接触反应

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长侧基甲壳型液晶高分子的合成及性质研究

高分子学报 2011年第11期21卷 1311-1319页

作者：梁小朝陈小芳 li Christopher y. 沈志豪范星河周其凤北京分子科学国家实验室高分子化学与物理教育部重点实验室北京大学化学与分子工程学院北京100871 Department of Materials Science and Engineering Drexel University Philadelphia PA 19104

设计并合成了一系列尾链为不同长度烷氧基的长侧基甲壳型液晶高分子聚[2,5-二(4'-烷氧基联苯氧羰基)苯乙烯](PnCbiPCS,n=4,6,8,10,14).这些聚合物都具有良好的热稳定性.偏光显微镜及一维和二维广角X射线衍射等研究结果表明PnCbiPCS这一... 详细信息

设计并合成了一系列尾链为不同长度烷氧基的长侧基甲壳型液晶高分子聚[2,5-二(4'-烷氧基联苯氧羰基)苯乙烯](PnCbiPCS,n=4,6,8,10,14).这些聚合物都具有良好的热稳定性.偏光显微镜及一维和二维广角X射线衍射等研究结果表明PnCbiPCS这一系列聚合物均能形成稳定的近晶A相结构,所对应的层间距随末端尾链的增长而增加,当n=4,6时层间距与侧基的理论长度相同,n≧8时层间距小于理论值,形成部分穿插的近晶A相结构.在剪切力场作用下,所有这些聚合物所形成的近晶相均易发生宏观取向,近晶层法线方向与剪切方向垂直.

关键词：甲壳型液晶高分子长侧基近晶相

Cutter Accessibility.Map and Its Application for 5-axis Milling Tool-path Generation

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武汉理工大学学报 2006年第S1期28卷 40-47页

作者： L. L. li,y. F. Zhang (Department of Mechanical Engineering,National University.of Singapore 9 Engineering Drive 1,Singapore 117576) Department of Mechanical Engineering National University of Singapore 9 Engineering Drive 1Singapore 117576

In tool-path generation process for 5-axis face milling,the specification of cutter posture is one of the critical issues that contribute to the computation load. In this paper,a quick algorithm is presented to specify.the cutter posture at a surface point based on the cutter’s accessibility.maps (A-maps) at all the sampled points,obtained during cutter selection. Integrated with this quick algorithm,an efficient approach is proposed to generate a set of iso-planar tool-paths for finishing a given surface withmaximum machining efficiency.without violating the desirable profile and scallop height tolerance. One example is given to confirm the validity.of the quick algorithm for cutter posture and the efficiency.of the algorithm for tool-path generation.

关键词： cutter accessibility map tool-path generation machining strip width step-over