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Anode Simulation and Cathode Design for Electrolytic Dressing of Diamond Profile Wheel

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Transactions of tianjin university 2005年第3期11卷 172-175页

作者：邹峰于爱兵谭业发 key laboratory for Advanced Ceramics and Machining {2. of Education Ministry School of Mechanical Engineering Tianjin University Tianjin 300072 China Nanjing Engineering Institute Nanjing 210007 China

The design methods of anode and cathode are proposed for precision profile grinding. Based on the electrolytic machining theory, electrolytic equilibrium condition and Faraday′s law of electrolysis are applied to establishing the mathematical model of profile diamond dressing process- es. A finite element method (FEM) program is developed to solve the inverse boundary problem of Laplace′s equation. Desired anode contour or cathode shape is determined by computing the distribution of electric potential layer by layer. Electrolytic machining experiment is carried out to verify the simulated anode shape. The research result shows that shape deviation between designed cathode and profile wheel increases with the value of angle between feed rate and the normal to anode surface. The shape of simulated anode is consistent with the contour of metal-bonded diamond profile wheel for a given cathode. Based on the anode contour, cathode shape can also be designed accurately.

关键词： profile wheel dressing electrolysis FEM diamond

Constructing G^2.Continuous Curve on Freeform Surface with Normal Projection

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Chinese Journal of Aeronautics 2010年第1期23卷 137-144页

作者： Wang Xiaoping,An Luling,Zhou Laishui,Zhang Liyan Jiangsu key laboratory of {2. and Macro-manufacturing technology,Nanjing university of Aeronautics and Astronautics,Nanjing 2.0016,china [a] Jiangsu key laboratory of {2. Macro-manufacturing technology Nanjing University of Aeronautics Astronautics Nanjing 210016 China

This article presents a new method for G2.continuous interpolation of an arbitrary sequence of points on an implicit or parametric surfaee with prescribed tangent direction and curvature vector, respectively, at every point. First, a G2.continuous curve is constructed in three-dimensional space. Then the curve is projected normally onto the given surface. The desired interpolation curve is just the projection curve, which can be obtained by numerieally solving the initialvalue problems for a system of first-order ordinary differential equations in the parametric domain for parametric case or in three-dimensional space for implicit ease. Several shape parameters are introduced into the resulting curve, which can be used in subsequent interactive modification so that the shape of the resulting curve meets our demand. The presented method is independent of the geometry and parameterization of the base surface. Numerical experiments demonstrate that it is effective and potentially useful in numerical control （NC） machining, path planning for robotic fibre placement, patterns design on surface and other industrial and research fields.

关键词： Hermite interpolation normal projection freeform surface G2.continuity ordinary differential equations

Distribution of Nb atom in the TiAl+Nb system

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Rare Metals 2001年第1期20卷 5-12页

作者： Xiaodong Ni, Xidong Hui, Guoliang Chen (Applied Science School, university of Science and technology Beijing, Beijing 100083, {2. state key laboratory for Advanced Metals and Materials, university of Science and technology Beijing, {2.) Appl. Sci. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

Based on MEAM (the modified embedded atom method) potential and an average atom model similar to B-W (Bragg-Williams) method, the distribution of Nb atoms in TiAl+Nb compounds with various composition was calculated. The calculation results showed that Nb atoms prefer to occupy the Ti sublattice of L10 structure for all compounds in question. With increasing atomic fraction of Nb and Al, Nb atoms exhibited a trend of ordered distribution on the Ti sublattice and result in a new L10 derivative superlattice structure.

关键词： Computer simulation Intermetallics Superlattices Ternary systems

Modeling of Air Temperature for Heat Exchange due to Vertical Turbulence and Horizontal Air Flow

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湖南大学学报（自然科学版） 2009年第S1期36卷 45-50页

作者： ZHANG Lei,MENG Qing-lin(state key {2. of Subtropical Building Science,South china university of technology,Guangzhou,Guangdong 510640,china) state key {2. of Subtropical Building Science South China University of Technology Guangzhou 510640 China

In order to calculate the air temperature of the near surface layer in urban environment,the surface layer air was divided into several layers in the vertical direction,and some energy balance equations were developed for each air layer,in which the heat exchange due to vertical turbulence and horizontal air flow was taken into ***,the vertical temperature distribution of the surface layer air was obtained through the coupled calculation using the energy balance equations of underlying surfaces and building ***,the measured air temperatures in a small area(with a horizontal scale of less than 500 m)and a large area(with a horizontal scale of more than 1 000 m)in Guangzhou in summer were used to validate the proposed *** calculated results agree well with the measured ones,with a maximum relative error of 4.18%.It is thus concluded that the proposed model is a high-accuracy method to theoretically analyze the urban heat island and the thermal environment.

关键词： turbulent heat exchange urban thermal environment near surface layer air temperature calculation model

Dominant point detecting based non-uniform B-spline approximation for grain contour

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Science china(Technological Sciences) 2007年第1期50卷 90-96页

作者： ZHAO XiuYang1, YIN YanSheng1,2.& YANG Bo3 1 Shandong key laboratory of Engineering Ceramics, Shandong {2., Jinan 2.0061, china 2.School of Materials, Ocean {2. of china, Qingdao 2.6003, china 3 state key laboratory of Advanced technology for Materials Synthesis and Processing, Wuhan {2. of Science and technology, Wuhan 430070, china 1. Shandong key laboratory of Engineering Ceramics Shandong University Jinan 250061 China 2. School of Materials Ocean University of China Qingdao 266003 China 3. state key {2. of Advanced technology for Materials Synthesis and Processing Wuhan University of Science and Technology Wuhan 430070 China

Three-dimension reconstruction from serial sections has been used in the last decade to obtain information concerning three-dimensional microstructural ge-ometry. One of the crucial steps of three-dimension reconstruction is getting compact and fairing grain contours. Based on the achievement of closed raw con-tours of ceramic composite grains by using wavelet and level set, an adaptive method is adopted for the polygonal approximation of the digitized raw contours. Instead of setting a fixed length of support region in advance, the novel method computes the suitable length of support region for each point to find the best es-timated curvature. The dominant points are identified as the points with local maximum estimated curvatures. Periodic closed B-spline approximation is used to find the most compact B-spline grain boundary contours within the given tolerance. A flexible distance selection approach is adopted to obtain the common knot vector of serial contours consisting of less knots that contain enough degrees of freedom to guarantee the existence of a B-spline curve interpolating each contour. Finally, a B-spline surface interpolating the serial contours is generated via B-spline surface skinning.

关键词： composite B-spline dominant points control points grain contour

X-ray flares of γ-ray bursts: Quakes of solid quark stars?

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Science china(Physics,Mechanics & Astronomy) 2009年第2期52卷 315-320页

作者： XU RenXin1 & LIANG EnWei2.1 School of Physics and state key {2. of Nuclear Physics and technology, Peking university, Beijing 100871, china 2.Department of Physics, Guangxi university, Nanning 530004, china 1. School of Physics and state key {2. of Nuclear Physics and technology Peking University Beijing 100871 China 2. Department of Physics Guangxi University Nanning 530004 China

A star-quake model is proposed to understand X-ray flares of both long and short γ-ray bursts (GRBs) in a solid quark star regime. Two kinds of central engines for GRBs are available if pulsar-like stars are actually (solid) quark stars, i.e., the SNE-type GRBs and the SGR-type GRBs. It is found that a quark star could be solidified about 103 to 106 s later after its birth if the critical temperature of phase transi- tion is a few Metga-electron-volts, and then a new source of free energy (i.e., elastic and gravitational ones, rather than rotational or magnetic energy) could be possible to power GRB X-ray flares.

关键词： γ-rays bursts: X-rays neutron stars elementary particles

Experimental and Finite Element Study of Steady state Micro-cutting Characteristics of Aluminum Alloy (2.12.

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Transactions of tianjin university 2011年第5期17卷 344-350页

作者：陈光任成祖靳新民郭韬 key laboratory of Advanced Ceramics and Machining {2. of Ministry of Education Tianjin University

This paper studies the micro-cutting characteristics of aluminum alloy (2.12. based on a series of orthogonal experiments and finite element method (FEM) simulations. An energy-based ductile failure law was proposed in the FEM simulation. The simulated cutting forces and chip morphology were compared with experimental results. The simulation result indicates that there is a close relationship between the cutting force and cutting heat. The micro-cutting force decreases as the heat flux vector increases. Both the cutting heat and the micro-cutting force need a finite time to achieve a steady state. It is observed that with the cutting speed of 169.95 m/min and uncut chip thickness of 6 μm, the heat flux vector in the workpiece increases to a stable value after 0.06 ms; meanwhile, the principal cutting force decreases to a steady state correspondingly, i.e., the micro-cutting process achieves the steady state. It is concluded that the steady state micro-cutting simulation can reflect the cutting process accurately.

关键词： micro-cutting aluminum alloy steady state finite element method

Preparation of well-defined polystyrene/silica hybrid nanoparticles by ATRP

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Science china Chemistry 2008年第1期51卷 51-57页

作者： OU BaoLi1,2.LI DuXin2.1 College of Chemistry and Chemical Engineering,Hunan university of Science and technology,Xiangtan 4112.1, {2. 2.state key laboratory of Powder Metallurgy,Central South university,Changsha 410083, {2. 1. College of Chemistry and Chemical Engineering Hunan University of Science and Technology Xiangtan 411201 China 2. state key {2. of Powder Metallurgy Central South University Changsha 410083 China

Immobilization of the atom transfer radical polymerization (ATRP) macroinitiators at the silica nanoparticle surfaces was achieved through surface modification with excess toluene-2.4-diisocynate (TDI), after which the residual isocyanate groups were converted into ATRP macroinitiators. Structurally well-defined polystyrene chains were grown from the nanoparticle surfaces to yield individual particles composed of a silica core and a well-defined, densely grafted outer polystyrene by ATRP, which was initiated by the as-synthesized silica-based macroinitiator. FTIR, NMR and gel permeation chro-matography (GPC) were used to characterize the polystyrene/silica hybrid particles.

关键词： silica nanoparticles surface modification atom transfer radical polymerization polystyrene hybrid particle

Numerical simulations of self-propelled swimming of 3D bionic fish school

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Science china(Technological Sciences) 2009年第3期52卷 658-669页

作者： WU ChuiJie1 & WANG Liang2.1 state key {2. of Structural Analysis for Industrial Equipment, Dalian university of technology, Dalian 11602., china 2.Research Center for Fluid Dynamics, People’s Liberation Army university of Science and technology, Nanjing 2.1101, china state key {2. of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 China Research Center for Fluid Dynamics People’s Liberation Army University of Science and Technology Nanjing 211101 China

Numerical simulations of self-propelled swimming of a three dimensional bionic fish and fish school in a viscous fluid are carried out. This is done with the assistance of a parallel software package produced for 3D moving boundary problems. This computational fluid dynamics package combines the adaptive multi-grid finite volume method, the immersed boundary method and VOF (volume of fluid) method. By using the package results of the self-propelled swimming of a 3D bionic fish and fish school in a vis- cous fluid are obtained. With comparison to the existing experimental measurements of living fishes, the predicted structure of vortical wakes is in good agreement with the measurements.

关键词： adaptive multi-grid immersed boundary method self-propelled swimming fish school 3D bionic fish