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The mathematical model of wetting angle of heterogeneous nucleation

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science china(Technological sciences) 2004年第4期47卷 391-397页

作者： HUANG Cheng1, SONG Bo1, MAO Jinghong2.& ZHAO Pei3.1. School of Metallurgical and Ecological engineering, University of science and Technology {2., {2. 100083. china 2. School of Material science, University of science and Technology {2., {2. 100083. china 3. Central Iron and Steel Research Institute, {2. 100081, china 1. School of Metallurgical and Ecological engineering University of Science and Technology Beijing 100083 Beijing China 2. School of Material science University of Science and Technology Beijing 100083 Beijing China 3. Central Iron and Steel Research Institute 100081 Beijing China

The heterogeneous nucleation has been analyzed in terms of the thermodynamic theory, and the mathematical model of wetting angle of heterogeneous nucleation has been developed based on the dynamic requirements of hetero- and homogeneous nucleation. With the wetting angel model, the wetting angles of different catalysts in liquid iron have been calculated. The result shows that the wetting angle of most catalysts is smaller than 40, and the value of f() is far less than 1. The wetting angles of TiN, TiC and RE2.3.are smaller, while the wetting angle of MnO is bigger among the ordinary nucleation catalysts. The wetting angles calculated by this model are in agreement with the results of other research work.

关键词： heterogeneous nucleation, mathematical model, wetting angle, undercooling.

Analysis for twinning and slip in face-centered cubic crystals under axisymmetric co-deformation

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science china(Technological sciences) 2006年第5期49卷 521-536页

作者： CHEN Zhiyong1,2. CAI Hongnian1, ZHANG Xinming2. WANG Fuchi1 & TAN Chengwen1,3.1. School of Material science and {3., {2. Institute of Technology, {2. 100081, china 2. School of Material science and {3., Central South University, Changsha 410083. china 3. School of Material science and {3., {2. University of Aeronautics and Astronautics, {2. 100083. china 1. School of Material science and engineering Beijing Institute of Technology Beijing 100081 China 2. School of Material science and engineering Central South University Changsha 410083 China 3. School of Material science and engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

The maximum work principle of Bishop-Hill was developed to analyze the axisymmetric co-deformation in face-centered cubic crystals (f.c.c.) for twinning on {111} 112.and slip on {111} 110 systems. The influence of ξ , the ratio of critical re- solved shear stress for twinning to slip, on the yield stress states and corresponding active slip or/and twinning systems for orientations in the standard stereographic triangle of cubic crystal was investigated systematically. The Taylor factors and the anisotropy of yield strength for three important orientations [100], [110] and [111] in orientation space were analyzed. It is found that the yield strength asymmetry for the case of axisymmetric de- formation of tension and compression can be explained based on the microscopic theory of crystal plasticity. The concept of orientation factor for twinning ability was proposed and the deformation mechanism map in the orientation space was established for the case of axisymmetric deformation. The deformation texture formation and development of f.c.c. crystals with low stacking fault energy for axisymmetric tension can be explained qualita- tively on the basis of analyzed results.

关键词： twinning slip face-centered cubic crystals axisymmetric co-deformation Bishop-Hill maximum work principle yield strength anisotropy

The refined theory of deep rectangular beams based on general solutions of elasticity

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science china(Physics,{2. & Astronomy) 2006年第3期49卷 291-303页

作者： GAO Yang1 & WANG Minzhong2.1. College of science, china Agricultural University, {2. 100083. china 2. State Key Laboratory for Turbulence and Complex Systems and Department of mechanics and Engi- neering science, Peking University, beijing 100871, china College of science China Agricultural University Beijing 100083 China State Key Laboratory for Turbulence Complex Systems Department of mechanics engineering science Peking University Beijing 100871 China

The problem of deducing one-dimensional theory from two-dimensional the- ory for a homogeneous isotropic beam is investigated. Based on elasticity theory, the re- fined theory of rectangular beams is derived by using Papkovich-Neuber solution and Lur’e method without ad hoc assumptions. It is shown that the displacements and stresses of the beam can be represented by the angle of rotation and the deflection of the neutral surface. Based on the refined beam theory, the exact equations for the beam without transverse surface loadings are derived and consist of two governing differential equations: the fourth-order equation and the transcendental equation. The approximate equations for the beam under transverse loadings are derived directly from the refined beam theory and are almost the same as the governing equations of Timoshenko beam theory. In two ex- amples, it is shown that the new theory provides better results than Levinson’s beam the- ory when compared with those obtained from the linear theory of elasticity.

关键词： deep rectangular beams,the refined theory,Papkovich-Neuber solution,Lur'e method,governing equation

The refined theory of transversely isotropic piezoelectric rectangular beams

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science china(Physics,{2. & Astronomy) 2006年第4期49卷 473-486页

作者： GAO Yang1 & WANG Minzhong2.1. College of science, china Agricultural University, {2. 100083. china 2. State Key Laboratory for Turbulence and Complex Systems and Department of mechanics and Engi- neering science, Peking University, beijing 100871, china 1. College of science China Agricultural University Beijing 100083 China 2. State Key Laboratory for Turbulence and Complex Systems and Department of mechanics and engineering {2. Peking University Beijing 100871 China

The problem of deducing one-dimensional theory from two-dimensional theory for a transversely isotropic piezoelectric rectangular beam is investigated. Based on the piezoelasticity theory, the refined theory of piezoelectric beams is derived by using the general solution of transversely isotropic piezoelasticity and Lur'e method without ad hoc assumptions. Based on the refined theory of piezoelectric beams, the exact equations for the beams without transverse surface loadings are derived, which consist of two governing differential equations: the fourth-order equation and the transcendental equation. The approximate equations for the beams under transverse loadings are derived directly from the refined beam theory. As a special case, the governing differential equations for transversely isotropic elastic beams are obtained from the corresponding equations of piezoelectric beams. To illustrate the application of the beam theory developed, a uniformly loaded and simply supported piezoelectric beam is examined.

关键词： rectangular beams, the refined theory, piezoelectric, transversely isotropic.

Development and Application of High Performance X80 Line Pipe for the 2.(nd) West-East Gas Pipeline

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Journal of Iron and Steel Research International 2011年第S1期18卷 39-48页

作者： LI He-lin 1 , HUO Chun-yong 1 , JI Ling-kang 1, 2., LI Yang 1, 3.(1. CNPC Tubular Goods Research Institute, Xi’an 710065, china 2. . School of Material {3. and {2., Xi’an Jiaotong University, Xi’an 710049, china 3. School of Material {3. and {2., University of {3. and Technology beijing, beijing 100083. china) CNPC Tubular Goods Res Inst Xian 710065 Peoples R China Xi An Jiao Tong Univ Sch Mat Sci & Engn Xian 710049 Peoples R China Univ Sci & Technol beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China

It is the development tendency of gas pipeline to improve strength of line pipe and transmission pressure, which is an important symbol of the progress of gas pipeline technology. The 2.d West-East Gas Pipeline (the 2.nd WEGP) is the largest-scale X80 high pressure gas pipeline project in the world. Through the joint development project by Pipeline Company, research institute, and steel company, a series of achievements of technology have been obtained, which makes it possible to apply pressure of 12.MPa and X80 LSAW and HSAW pipe for the 2.nd WEGP. Specifications of X80 steel and pipe have been issued based on API 5L. High performance X80 steel and pipe have been developed and meets the Specification. General design conception of applying HSAW pipe and LSAW pipe on gas transmission trunk line with large diameter and high pressure has been established. Failure control of the 2.nd WEGP has been carried out to avoid failure and reduce the lost which based on analysis of pipeline failure mode. In this paper, research and development of high performance X80 welded pipe, establishment of technical route of joint application of HSAW and LSAW steel pipe and key technology of failure control are emphatically discussed.

关键词： 2.nd WEGP acicular ferrite failure control arrest toughness strain-based design

Solving the input data in error correc-tion of optical fabrication by finite Fourier coefficient algorithm

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science china(Technological sciences) 2006年第1期49卷 50-60页

作者： CHENG Haobo1,2. SUN Guozheng3.& FENG Zhijing2.1. Department of Optical engineering, {3. Institute of Technology, {3. 100081,{3. 2. Department of Precision Instruments and Mechanology, Tsinghua University, {3. 100084,{3. 3.{3. North Industries Group Corporation, {3. 100089,{3. 1. Department of Optical engineering Beijing Institute of Technology Beijing 100081 China 2. Department of Precision Instruments and Mechanology Tsinghua University Beijing 100084 China 3. china North Industries Group Corporation Beijing 100089 China

A free-form lens (FFL) is a special surface that is difficult to be fabricated. FFL are usually fabricated by computer-controlled optical surfacing (CCOS) technique. During CCOS, the material removal amount is determined by the unit removal function (URF) convoluting with the input data――the dwell time. When the removal amount and the URF are known, how to solve the input data involves the special algorithm――deconvolution. Usually, the input data are solved by virtue of low pass filter or iterative methods. However, an approximation solution would destroy the machining stability nec-essary to perform precisely CCOS. In this paper, to solve the input data, a new method that is based on the finite Fourier coefficient is put forward. It can give a continuous and accurate solution for fabricating choice. Several parameters are simulated, which influ-ence the process of CCOS, and evaluating on the effect of the method is also carried out. Experimental results verify that this method is suitable for guiding the manufacturing of high precision FFL.

关键词： optical fabrication, computer controlled optical surfacing, free-form lens, finite Fourier coefficient, error correction.

Intermediate processes and critical phenomena: Theory, method and progress of fractional operators and their applications to modern mechanics

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science china(Physics,{2. & Astronomy) 2006年第3期49卷 257-272页

作者： XU Mingyu1 & TAN Wenchang2.1. Institute of Applied Mathematics, School of Math & System science, Shandong University, Jinan 2.0100,{3. 2. State Key Laboratory of Turbulence and Complex Systems & Department of {2. and {3. science, Peking University, beijing 100871,{3. 1. Institute of Applied Mathematics School of Math & System Science Shandong University Jinan 250100 China 2. State Key Laboratory of Turbulence and Complex Systems & Department of mechanics and engineering {2. Peking University Beijing 100871 China

From point of view of physics, especially of mechanics, we briefly introduce fractional operators (with emphasis on fractional calculus and fractional differential equa- tions) used for describing intermediate processes and critical phenomena in physics and mechanics, their progress in theory and methods and their applications to modern me- chanics. Some authors’ researches in this area in recent years are included. Finally, prospects and evaluation for this subject are made.

关键词： fractional operators,intermediate processes,critical phenomena,modern mechanics

A low frequency piezoelectric power harvester using a spiral-shaped bimorph

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science china(Physics,{2. & Astronomy) 2006年第6期49卷 649-659页

作者： HU Yuantai1,2.HU Hongping2.& YANG Jiashi3.1. Institute of mechanics and Sensing Technology,Central South University,Changsha 410083.{3. 2. Department of mechanics,Huazhong University of {3. and Technology,Wuhan 43.074,{3. 3. Department of engineering mechanics,University of Nebraska,Lincoln,NE 68588-052.,USA 1. Institute of mechanics and Sensing Technology Central South University Changsha 410083 China 2. Department of mechanics Huazhong University of Science and Technology Wuhan 430074 China 3. Department of engineering mechanics University of Nebraska Lincoln NE 68588-0526 USA

We propose a spiral-shaped piezoelectric bimorph power harvester operating with coupled flexural and extensional vibration modes for applications to low frequency energy sources. A theoretical analysis is performed and the computational results show that the spiral structure has relatively low operating frequency compared to beam power harvesters of the same size. It is found that to optimize the performance of a piezoelectric spiral-shaped harvester careful design is needed.

关键词： spiral-shaped bimorph,piezoelectric harvester,power density.

A novel endorectal RF coil for high resolution MRI and spectroscopy of the prostate

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Progress in Natural science:Materials International 2005年第5期15卷 472-476页

作者： ZHANG Hongjie 1,2. SONG Xiaoyu1, WANG Xiaoying3. XU Pingfang1 and BAO Shanglian1*(1. beijing Key Laboratory of Medical Physics & engineering, Peking University,{2.,{3. 2. Navy General Hospital, beijing 10003.,{3. 3. Peking University First Hospital, beijing 10003.,{3.) beijing Key Laboratory of Medical Physics & engineering Peking University Beijing 100871 China Navy General Hospital Beijing 100037 China Peking University First Hospital Beijing 100034 China

The diagnosis of prostate diseases by magnetic resonance imaging (MRI) in vivo is sometimes difficult for the lower signal to noise ratio (SNR). To increase the SNR of the prostate image, we designed a RF coil that can be inserted into rectum and was named endorectal coil. The properties of RF coil were evaluated using a network analyzer. Moreover the images and spectroscopy of a special phantom were acquired and the results were compared to those of the commercial TORSO coil (G.E. Medical Systems, USA). Our coil gave a significantly higher SNR at the region of interest (ROI). The achieved high local SNR and resulting high spatial resolution would add more anatomic and biochemical information to the diagnosis of prostate diseases.

关键词： MRI RF coil endorectal coil.