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Superconductivity of small metal grains

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Science china(Physics,Mechanics & Astronomy) 2005年第4期48卷 431-441页

作者： ZHENG Renrong1 CHEN Zhiqian2 & ZHU Shunquan1,3.1. department of Physics, Shanghai Normal University, Shanghai 20023., china 2. department of Physics, Southwest Normal University, Chongqing 400715, china 3. department of Computer and Electric technology, Shanghai Business School, Shanghai 201400, china department of Physics Shanghai Normal University Shanghai China department of Physics Southwest Normal University Chongqing China department of Computer and Electric technology Shanghai Business School Shanghai China

The formulas of the energy gap and superconducting critical temperature appropriate for systems with both odd and even number of electrons are derived; the bases of the derivations are BCS theory and energy level statistics. Numerical results qualitatively agree with the experimental phenomena. i.e., the superconductivity of small metallic grains will first enhance then decrease to zero when the grain are getting smaller and smaller. The calculations indicate that the above phenomena happen in the metallic grains belonging to Gaussian Orthogonal Ensemble (GOE) and Gaussian Unitary ensemble (GUE) with zero spin; The superconductivity of small metallic grains in Gaussian Symplectic Ensemble (GSE) will monotonically decrease to zero with the decreasing of the grain size. The analyses suggest that the superconductivity enhancements come from pairing and the balance of the strengths between spin-orbital coupling and external magnetic field. In order to take the latter into account, it is necessary to include the level statistics given by Random Matrix Theory (RMT) in describing small metallic grains.

关键词： size effect, superconductivity enhancements, small metallic grains.

A MECHANICS MODEL FOR CIRCULAR FORM TOOL CUTTING

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中国有色金属学会会刊：英文版 1996年第2期6卷 86-90,94页

作者： Xia Wei Li Yuanyuan Zhou Zehua (department of Mechanical Engineering,South china University of technology, {3. 510641) department of Mechanical Engineering South China University of Technology Guangzhou 510641 China

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关键词： metal cutting mechanical medel circular form tcol

Parameter identification theory of a complex model based on global optimization method

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Science china(Physics,Mechanics & Astronomy) 2008年第11期51卷 1722-1732页

作者： QU Jie1, JIN QuanLin2 & XU BingYe3.1 College of Automotive Engineering, South china University of technology, guangzhou 510640, china 2 Beijing Research Institute of Mechanical and Electrical technology, Beijing 100083. china 3.department of Engineering Mechanics, Tsinghua University, Beijing 100084, china College of Automotive Engineering South China University of Technology Guangzhou China Beijing Research Institute of Mechanical and Electrical technology Beijing China department of Engineering Mechanics Tsinghua University Beijing China

With the development of computer technology and numerical simulation technology, computer aided engineering (CAE) technology has been widely applied to many fields. One of the main obstacles, which hinder the further application of CAE technology, is how to successfully identify the parameters of the selected model. An elementary framework for parameter identification of a complex model is provided in this paper. The framework includes the construction of objective function, the design of the optimization method and the evaluation of the identified results, etc. The parameter identification process is described in this framework, taking the parameter identification of the superplastic constitutive model considering grain growth for Ti-6Al-4V at 927°C as an example. The objective function is the weighted quadratic sums of the difference between the experimental and computational data for the stress-strain relationship and the grain growth relationship; the designed optimization method is a hybrid global optimization method, which is based on the feature of the objective function and incorporates the strengths of genetic algorithm (GA), the Levenberg-Marquardt algorithm and the augmented Gauss-Newton algorithm. The reliability evaluation of parameter identification result is made through the comparison between the calculated and experimental results and between the theoretical values of the parameters and the identified ones.

关键词： constitutive model parameter identification theory inverse analysis global optimization

Calculation of Inelastic Neutron Scattering on ^(11)B

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Chinese journal of nuclear physics 1995年第3期17卷 265-267页

作者： Xie Wen-fang department of Physics,Guangdong University of technology,guangzhou 510090Ruan Wen-ying department of Physics,South china University of technology,guangzhou 510641 广东工业大学物理系广东广州 510090 华南理工大学物理系广东广州

The microscopic DWBA was used to calculate the inelastic neutron scattering on 11B to 2.14MeV excited state and some energy dependent parameters were used to improve the *** inte-grated inelastic cross sections and the angular distributions of the 11B（n,n′）11B*（2.14 MeV excitedstate）were given for the incident neutrons whose energy varies from 7.54 MeV to 20.0 *** also given for the experimental blank data.

关键词： Inelastic neutron scattering Microscopic DWBA Integrated cross section Angular distribution

Experimental Investigation on Viscosity of Cu-H_2O Nanofluids

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Journal of Wuhan University of technology(Materials Science) 2009年第1期24卷 48-52页

作者：李新芳 department of Packaging & Printing Zhongshan Torch Vocation and Technology College

A procedure for preparing a nanofluid that a solid-liquid composite material consists of solid nanoparticles with sizes typically of 1-100 nm suspended in liquid was proposed. By means of the procedure, Cu-H2O nanofluids with and without dispersant were prepared, whose sediment pho-tographs and particle size distribution were given to illustrate the stability and evenness of suspension with dispersant. The viscosity of Cu-H2O nanofluid was measured using capillary viscometers. The mass fractions（w） of copper nanoparticles in the experiment varied between 0.04% and 0.16% with the temperature range of 3.-70 ℃. The experimental results show that the temperature and SDBS concentration are the major factors affecting the viscosity of the nano-copper suspensions, while the effect of the mass fraction of Cu on the viscosity is not as obvious as that of the temperature and SDBS dispersant for the mass fraction chosen in the experiment. The apparent viscosity of the copper nano-suspensions decreases with the temperature increase, and increases slightly with the increase of the mass fraction of SDBS dispersant, and almost keeps invariability with increasing the mass fraction of Cu. The influence of SDBS concentration on the viscosity of nano-suspension was relatively large comparing with that of the nanoparticle concentration.

关键词： nano-Cu/water suspension SDBS kinematic viscosity capillary viscometer

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, 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 department of Optical Engineering Beijing Institute of Technology Beijing China department of Precision Instruments and Mechanology Tsinghua University Beijing China china North Industries Group Corporation Beijing 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.

Three-dimensional configurations of organic/inorganic hybrid nanostructural blocks (I).A quantum mechanical investigation for ladder-like structure of vinylsilsesquioxane

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Science china Chemistry 2004年第5期47卷 388-395页

作者： ZHANG Xingwen1,2, HU Lijiang1, HUANG Yudong1, SUN Dezhi2 & SUN Yi3.1. department of Applied Chemistry,Harbin Institute of technology, HUANG Yudong, Harbin 150001, china 2. department of Environmental Engineering, Harbin Institute of technology, Harbin 150001, china 3. department of Experimental Mechanics,Harbin Institute of technology, Harbin 150001, china Dept. of Applied Chem. Harbin Inst. of Technol. Harbin 150001 China Dept. of Environ. Eng. Harbin Inst. of Technol. Harbin 150001 China Dept. of Experimental Mech. Harbin Inst. of Technol. Harbin 150001 China

The organic/inorganic hybrid nanostructural vinylsilsesquioxanes (VSSO) were prepared from the hydrolytic condensation of vinyltrimethoxysilane (VMS). The proposed formu- las of VSSO were assigned with standard spectroscopic techniques, FTIR, NMR (1H, C and 13.29Si) and MALDI-TOF MS, and a generic formula of the SSO, Tn(OH)x(OR’)y(x, y = 0, 1, 2…; n = 1, 2…; T = RSiO1.5 ?(x+y)/2n). Geometric parameters (Si-O and Si-C bond lengths, Si-O-Si and O-Si-O bond angles) and total energies of the multi-structures of VSSO were calculated by a quantum mechanical investigation and molecular symmetries. According to the results of the calculation, most molecules had stabler ladder structures than the cage isomers, therefore, the most probably reasonable and optimum structure of the VSSO system was the ladder type.

关键词： vinyltrimethoxysilane (VMS), silsesquioxanes (SSO), sol-gel process, quantum mechanical calculation, MNDO.

A floral organ moving like a caterpillar for pollinating

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Journal of Systematics and Evolution 2010年第2期48卷 102-108页

作者： 1,3.4Zhong-Jian LIU 1Li-Jun CHEN 1,2,3.e-Wei LIU 1Li-Qiang LI 1Wen-Hui RAO 1(The National Orchid Conservation Center of china/The Orchid Conservation & Research Center of shenzhen,shenzhen 518114,{3.) 2(School of Life Sciences,University of Science & technology of china,Hefei 23.027,{3.) 3.The Center for Biotechnology and BioMedicine,Graduate School at shenzhen,Tsinghua University,shenzhen 518055,{3.) 4(College of Forestry,South china Agricultural University,guangzhou 510642,{3.) (The National Orchid Conservation Center of china/The Orchid Conservation & Research Center of shenzhen Shenzhen 518114 China) (The Center for Biotechnology and BioMedicine Graduate School at Shenzhen Tsinghua University Shenzhen 518055 China) (College of Forestry South China Agricultural University Guangzhou 510642 China) (School of Life Sciences University of Science & Technology of China Hefei 230027 China)

A new pollination mechanism is reported of an orchid species,Bulbophyllum penicillium,based on a field observation in Southeast Yunnan of *** species has a sensitive lip,and there is a distance of 2-3.mm between it and column *** the lip is touched by a landing insect,it will move up and down or swing left and right continuously,just like a moving *** suck a lip movement,the pollinator,a very small fruit fly (Drosophila sp.) ca.1 mm in height,will be pressed toward the column apex where anther and stigma are located,and then cross-pollination takes *** unique mode of pollination,depending on the movement of lip rather than insect itself,has never been found before in either Orchidaceae or other families of angiosperms.

关键词： pollination mechanism Bulbophyllum penicillium Drosophila lip movement

Simulation study of phase retrieval for hard X-ray in-line phase contrast imaging

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Science china(Physics,Mechanics & Astronomy) 2005年第4期48卷 450-458页

作者： YU Bin1,2, PENG Xiang1,2, TIAN Jindong1, NIU Hanben1, DIAO Luhong3.& LI Hua3.1. Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education, Institute of Optoelec- tronics, shenzhen University, shenzhen 518060, china 2. State Key Laboratory of Precision Measuring {3. and Instruments, Tianjin University, Tianjin 3.0072,china 3. Key Laboratory of Intelligent Information Processing, Institute of Computing {3., Chinese Academy of Sciences, Beijing 100080,china Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education Institute of Optoelectronics Shenzhen University Shenzhen China State Key Laboratory of Precision Measuring technology and Instruments Tianjin University Tianjin China Key Laboratory of Intelligent Information Processing Institute of Computing Technology Chinese Academy of Sciences Beijing China

Two algorithms for the phase retrieval of hard X-ray in-line phase contrast imaging are presented. One is referred to as Iterative Angular Spectrum Algorithm (IASA) and the other is a hybrid algorithm that combines IASA with TIE (transport of intensity equation). The calculations of the algorithms are based on free space propagation of the angular spectrum. The new approaches are demonstrated with numerical simulations. Comparisons with other phase retrieval algorithms are also performed. It is shown that the phase retrieval method combining the IASA and TIE is a promising technique for the application of hard X-ray phase contrast imaging.

关键词： X-ray optics, phase contrast imaging, phase retrieval, angular spectrum, hard X-ray.