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ELASTOHYDRODYNAMIC LUBRICATION OF LOGARITHMIC PROFILE ROLLER CONTACTS

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Chinese Journal of Mechanical Engineering 2001年第4期14卷 347-352页

作者： Chen Xiaoyang, Shen Xuejin (Research Institute of Bearings,Shanghai university) Xu Wen, Ma Jiaju (Zhejiang university) 上海大学上海浙江大学浙江

An account of numerical solutions to the isothermal and flooded elastohydrodynamic lubrication(EHL)of a logarithmic profile roller,which is rolling over a flat plane,is given The analysis takes account of sideways flow of lubricant in the inlet region of the contact When the results are presented in suitable non dimensional groups,it is shown that more uniformly pressure and shape of the film distributing in axial direction is taken place under light loading As the increase of the load,the end closure is displayed and the oil pressure rises sharply at the ends The seal action formed by the end closure makes the film thickness a little And the minimum film thickness is transferred from the central to the ends and the value is reduced rapidly As the increase of the speed,the end closure becomes much serious The optimum crowning value obtained in EHL state is larger than the design value obtained in elastostatic contact state for the same working conditions In order to verify the correctness of theory,optical interferometry is applied to measure the oil film thickness between a logarithmic profiled roller and a glass plate under pure rolling conditions It is found the agreement between numerical solutions and experiments is very good.

关键词： Elastohydrodynamic lubrication(EHL) Logarithmic profile roller Finite line contacts Optical interferom etry measurement

Inflow conditions for spatial direct numerical simulation of turbulent boundary layers

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Science China(Physics,Mechanics & Astronomy) 2008年第8期51卷 1106-1115页

作者： HUANG ZhangFeng & ZHOU Heng Department of Mechanics,Tianjin university,Tianjin 300072,China Liu-Hui Center of Applied Mathematics,Nankai university and Tianjin university,Tianjin 300072,China Department of Mechanics Tianjin University Tianjin China Liu-Hui Center of Applied Mathematics Nankai University and Tianjin University Tianjin China

The inflow conditions for spatial direct numerical simulation(SDNS) of turbulent boundary layers should reflect the characteristics of upstream turbulence,which is a puzzle. In this paper a new method is suggested,in which the flow field obtained by using temporal direct numerical simulation(TDNS) for fully developed turbulent flow(only flow field for a single moment is sufficient) can be used as the inflow of SDNS with a proper transformation. The calculation results confirm that this method is feasible and effective. It is also found that,under a proper time-space transformation,all statistics of the fully developed turbulence obtained by both temporal mode and spatial mode DNS are in excellent agreement with each other,not only qualitatively,but also quantitatively. The normal-wise distributions of mean flow profile,turbulent Mach number and the root mean square(RMS) of the fluctuations of various variables,as well as the Reynolds stresses of the fully developed turbulence obtained by using SDNS,bear similarity in nature.

关键词： inflow conditions spatial direct numerical simulation turbulent boundary layer similarity

Aggregation and assembly of crescent foldamers

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Science China Chemistry 2010年第1期53卷 45-51页

作者： GONG Bing Department of Chemistry,university at Buffalo,The State university of New York,Buffalo,New York 14260,USA Department of Chemistry University at Buffalo The State University of New York Buffalo USA

Recent studies have started to provide initial insights into the aggregation and assembly of two classes of back-rigidified foldamers with flat,curved backbones consisting of aromatic *** their persistent shape that presents large,well-defined aromatic surface areas,these crescent foldamers were found to undergo size-dependent aggregation in solution and pack into 1D assemblies in the solid *** aromatic oligoamides undergo stacking interactions not only in polar solvents but also in nonpolar ones,a unique property that is not associated with many other molecules that associate via π-π stacking *** stacking of oligo(m-phenylene ethynylenes) is similar to aromatic hydrocarbons,being promoted in polar solvents such as methanol while being discouraged in nonpolar solvents such as *** ready synthetic availability of crescent foldamers makes it possible to directly control the intermolecular interaction by tuning surface ***,the columnar assembly of these cavity-containing molecules provides a new strategy for constructing supramolecular nanotubular structures.

关键词： foldamer folding hydrogen bond π-π stacking aggregation assembly

TEM OBSERVATION OF LOCAL DEFORMATION BAND AT CRACK TIP

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Acta Metallurgica Sinica(English Letters) 1992年第3期5卷 147-153页

作者： YAO Kefu university of Science and Technology Beijing,Beijing,ChinaTANG Naivong CHEN Nanping Tsinghua university,Beijing,China Beijing Univ of Science and Technology Beijing China

The thin foil specimen of a ferrite-austenite duplex stainless steel was tensiled under transmis- sion electron microscope(TEM).It was found that both in ferrite and austenite the local deformation band at crack tip was formed near to the crack propagating *** forma- tion was related with the crack tip Schmid factor,dislocation shielding,latent hardening and hardening *** the crack tip emitted dislocations to a slip system by the action of pure mode Ⅱ stress resolute,and the decreasing rate of hardening coefficient was suitable,lo- cal deformation band was easy to form.

关键词： crack tip local deformation band dislocation shielding

Preparation and characterization of bis(dimolybdo-nonatungstogermanate)lanthanates of potassium

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Rare Metals 2003年第1期22卷 6-9页

作者： WU QingyinDepartment of Chemistry, Zhejiang university, Hangzhou 310027, China Department of Chemistry Zhejiang University Hangzhou 310027 China

The heteropoly complexes K_(13)[Ln(GeW_9Mo_2O_(39))_2] centre dot nH_2O (Ln =La, Ce, Pr, Nd, and Sm) were prepared for the first time and characterized by chemical analysis,infrared (IR) spectrum, ultraviolet (UV) spectrum, X-ray powder diffraction, and thermal ***, UV spectra, and X-ray powder diffraction studies show that the structure of the heteropolycomplexes is a square antiprism consisting of eight oxygen atoms of two GeW_9Mo_2O_(39)^(8-)heteropolyanions and a lanthanide ion. The thermostability of heteropoly complexes is lower thanthat of saturated Keggin structure dodecatungstogermanate.

关键词： inorganic chemistry heteropoly complex chemical synthesis lanthanates germanium

Manufacturing Titanium Metal Matrix Composites by Consolidating Matrix Coated Fibres

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Journal of Materials Science & Technology 2005年第5期21卷 647-651页

作者： Hua-Xin PENGDepartment of Aerospace Engineering, university of Bristol, university Walk, Bristol, BS8 1TR, UK Department of Aerospace Engineering University of Bristol University Walk

Titanium metal matrix composites （TiMMCs） reinforced by continuous silicon carbide fibres are being developed for aerospace applications. TiMMCs manufactured by the consolidation of matrix-coated fibre （MCF） method offer optimum properties because of the resulting uniform fibre distribution, minimum fibre damage and fibre volume fraction control. In this paper, the consolidation of Ti-6Al-4V matrix-coated SiC fibres during vacuum hot pressing has been investigated. Experiments were carried out on multi-ply MCFs under vacuum hot pressing （VHP）. In contrast to most of existing studies, the fibre, arrangement has been carefully controlled either in square or hexagonal arrays throughout the consolidated sample. This has enabled the dynamic consolidation behaviour of MCFs to be demonstrated by eliminating the fibre re-arrangement during the VHP process. The microstructural evolution of the matrix coating was reported and the deformation mechanisms involved were discussed.

关键词： Titanium matrix composites Matrix-coated fibres Vacuum hot pressing Microstructure Dynamic denslfication

MIXED FINITE ELEMENT METHODS FOR A STRONGLYNONLINEAR PARABOLIC PROBLEM

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Journal of Computational Mathematics 1999年第2期17卷 209-220页

作者： Yan-ping Chen(Department of Mathematics, Nanjing university, Naming 210008, China Institute ofComputational and Applied Mathematics, Xiangtan university, Hunan 411105, China) 南京大学数学系江苏南京

A mixed finite element method is developed to approximate the solution of a strongly nonlinear second-order parabolic problem. The existence and uniqueness of the approximation are demonstrated and L-2-error estimates... 详细信息

关键词： finite element method nonlinear parabolic problem

Energy Harvesting——Technical Analysis of Evolution,Control Strategies,and Future Aspects

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Journal of Electronic Science and Technology 2019年第2期17卷 116-125页

作者： MD. Shahrukh Adnan Khan Md. Tanbhir Hoq A. H. M. Zadidul Karim Md. Khairul Alam Masum HowladerRajkumar Rajprasad Kumar School of Science and Engineering Canadian University of Bangladesh Dhaka 1213 Bangladesh Department of Electrical and Electronic Engineering University of Asia Pacific Dhaka 1215 Bangladesh Department of Electrical and Electronic Engineering University of Nottingham Malaysia Campus Semenyih 43500 Malaysia

This paper provides a technical analysis of energy harvesting (EH) in the field of power and energy sector, including different aspects of harvesting energy, individual case history, control strategies of harvesting in the field of power and energy sector together with the current trend and future aspects of it. EH is comparatively a new concept which is growing very fast since the 20th century and catching new generation research approaches. This paper not only describes the past and current scenarios of harvesting energy with radio frequency (RF) and renewables but also gives author’s own anticipation of the upcoming future trends of it by comparing the case histories.

关键词： Energy harvesting (EH) piezoelectric radio frequency (RF) solar triboelectric wind

NOVEL 6-SPS PARALLEL 3-DIMENSIONAL PLATFORM MANIPULATOR AND ITS FORCE/MOTION TRANSMISSION ANALYSIS

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Chinese Journal of Mechanical Engineering 2002年第4期15卷 298-302页

作者： Jin Zhenlin School of Mechanical Engineering, Yanshan university, Qinhuangdao 066004, ChinaGao Feng Hebei university of Technology School of Mechanical Engineering Yanshan University Qinhuangdao 066004 Hebei university of Technology

The unique design for a novel 6-SPS parallel 3-dimensional platformmanipulator with an orthogonal configuration is investigated. The layout feature of the parallelmanipulator is described. Its force/motion transmission capability, evaluation criteria arepresented. At the orthogonal configuration, the criteria and the relationships between the criteriaand the link lengths are analyzed, which is important since it can provide designer a piece ofvaluable information about how to choose the linear actuators. From the analysis of the results itis shown that the force/motion transmission capabilities of the parallel manipulator arecharacterized by isotropy at the orthogonal configuration. The manipulator is particularly suitablefor certain applications in 6-DOF micromanipulators and 6-axis force/moment transducers.

关键词： 6-SPS parallel manipulator 3-dimensional platform manipulator isotropy