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The refined theory of transversely isotropic piezoelectric rectangular beams

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science{1.(Physics,Mechanics & Astronomy) 2006年第4期49卷 473-486页

作者： gao yang1.& wang minzhong2 1. college of science,{1. agricultural University, beijing 1.0083,{1. 2. State Key Laboratory for Turbulence and Complex Systems and Department of Mechanics and Engi- neering science, Peking University, beijing 1.0871.{1. 1. college of {1. China Agricultural University Beijing 100083 China 2. State Key Laboratory for Turbulence and Complex Systems and Department of Mechanics and Engineering science 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.

The refined theory of deep rectangular beams for symmetrical deformation

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science{1.(Physics,Mechanics & Astronomy) 2009年第6期52卷 919-925页

作者： gao yang1.& wang minzhong2 1 college of science, china agricultural University, beijing 1.0083, china 2 State Key Laboratory for Turbulence and Complex Systems and Department of Mechanics and Aerospace Engineering, Peking University, beijing 100871, china college of {1. China Agricultural University Beijing 100083 China State Key Laboratory for Turbulence and Complex Systems and Department of Mechanics and Aerospace Engineering Peking University Beijing 100871 China

Based on elasticity theory, various one-dimensional equations for symmetrical deformation have been deduced systematically and directly from the two-dimensional theory of deep rectangular beams by using the Papkovich-Neuber solution and the Lur'e method without ad hoc assumptions, and they construct the refined theory of beams for symmetrical deformation. It is shown that the displacements and stresses of the beam can be represented by the transverse normal strain and displacement of the mid-plane. In the case of homogeneous boundary conditions, the exact solutions for the beam are derived, and the exact equations consist of two governing differential equations: the second-order equation and the transcendental equation. In the case of non-homogeneous boundary conditions, the approximate governing differential equations and solutions for the beam under normal loadings only and shear loadings only are derived directly from the refined beam theory, respectively, and the correctness of the stress assumptions in classic extension or compression problems is revised. Meanwhile, as an example, explicit expressions of analytical solutions are obtained for beams subjected to an exponentially distributed load along the length of beams.

关键词： deep rectangular beams the refined theory symmetrical deformation the Papkovich-Neuber solution the Lur’e method

Pattern phenomena in an rf discharge dusty plasma system

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science{1.(Physics,Mechanics & Astronomy) 2006年第5期49卷 588-596页

作者： HUANG Feng1.2, YE Maofu2 & wang Long2 1. {1. of science, china agricultural University, beijing 1.0083, china 2. Institute of Physics, Chinese Academy of sciences, beijing 1.0080, china 1. college of {1. China Agricultural University Beijing 100083 China 2. Institute of Physics Chinese Academy of Sciences Beijing 100080 China

Various dust patterns are observed in an rf discharge dusty plasma system. According to the dust growth process from small to large in size, the formation of different dust patterns can be divided into two stages: the small-particle stage (or dust cloud stage), and the large-particle stage (or dust crystal stage). The evolution relations between different dust patterns with gas pressure changing are investigated. Dust voids, dust acoustic waves and strong turbulence modes are presented at the small-particle stage. The self-organized dust lattices and dust clusters are investigated at the large-particle stage. The static structure of a dust lattice is characterized by means of the pair correlation function. Dust clusters formed by particles with different numbers and the regular evolution of the clusters with gas pressure are also investigated. The packing sequences of dust clusters are verified through two-dimensional confined molecular dynamics simulations.

关键词： dusty plasma dust patterns

Effect and mechanism of stresses on rock permeability at different scales

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science{1. Earth sciences 2006年第7期49卷 714-723页

作者： YIN Shangxian1.& wang Shangxu2 1. Safety Engineering {1., North china Institute of science and Technology, Yanjiao, beijing 1.1.01. china 2. Key Laboratory of Geophysics Exploration, china University of Petroleum, beijing 1.0083, china 1. Safety Engineering college North China Institute of Science and Technology Yanjiao Beijing 101601 China 2. Key Laboratory of Geophysics Exploration China University of Petroleum Beijing 100083 China

The effect of geo-stress fields on macroscopic hydro-geological conditions or micro-cosmic permeability of water-bearing media should follow some laws or principles. Cases study and tests show that: (1. At macro-geologic large scale, deformed and crashed rocks which were induced by geo-stress fields changing provided space for groundwater storage and flow. Groundwater adjusts water-bearing space and dilatants fractures by flowing and press transferring. Coupling of liquid and solid can be implemented for rocks and groundwater. Although tectonic fields witness several times of change and build-up in geological time, stress fields forming regional tectonic framework are coherent with seepage fields, orientation of the maximum horizontal stress demonstrates main seepage direc-tions. (2) At macro-geologic middle scale, zones of stresses changing sharply, quite low stresses, stress or shear concentration can be used to show locations and types of main fractures, zones of geo-stresses changing equably can be acted as normal base media zones of tri-porosity media. (3) At micro-geologic small scale, tri-porosity media include fractured rocks, porous rocks and capillary rocks. Investigations indicate that porosity or permeability is functions of effective stresses, and po-rosity or permeability changing rules of porous rocks with variation of effective stresses can be de-scribed as the index model, the model of power exponent functions is suitable for those of fractured rocks, the model of the second power parabola for capillary rocks. The porosity and permeability loss in fractured rocks, which are greater than that in porous rocks, are shown by calculation of effective compressive coefficient and closing pressure in cracks. The calculations can also explain the mecha-nism why porosity changes are always larger than permeability changes. It is proved by the thick wall cylinder theory that the second power parabola relation between porosity or permeability loss and effective

关键词： geo-stress fields, seepage fields, tri-porosity media, effective stresses, permeability, porosity,scale.

Production of porcine cloned transgenic embryos expressing green fluorescent protein by somatic cell nuclear transfer

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science{1.(Life sciences) 2006年第2期49卷 164-171页

作者： ZHANG Yunhai1. PAN Dengke1.2, SUN Xiuzhu1. SUN Guojie1. wang Xiaobo1. LIU Xiaohui1. LI Yan1. DAI Yunping1.& LI Ning1.1. State Key Laboratory for Agrobiotechnology,{1. agricultural University, beijing 1.0094,{1. 2. college of Animal science and Technology,{1. agricultural University, beijing 1.0094,{1. State Key Laboratory for Agrobiotechnology China Agricultural University Beijing 100094 China college of Animal {1. Technology China Agricultural University Beijing 100094 China

In the present study, nuclear transferred embryos (NTEs) were reconstructed by using pig fetal fibroblasts as donors; in vitro matured oocytes as recipients. The effects of G41. selection on donor cells, duration of IVM of prepubertal gilt oocytes; oxygen tension in IVM of oocytes were investigated. The results were as follows: (i) When G41. selected cells expressing GFP were used as donors, the cleavage rate of NTEs decreased drastically in comparison to NTEs derived from donors without antibiotic selection (47.5% vs. 71.6%, p>0.05). For the blastocyst rate, no significant difference was observed between two groups (1.% vs. 1..4%, p2 h (83.6% vs. 96.7%, p>0.05). However, no statistical difference was observed between NTEs derived from oocytes of 36 h IVM group; NTEs from oocytes of 42 h IVM group in the rates of cleavage (59.3% vs. 73.6%, p1..2%, p2) tension; NTEs derived from oocytes matured under higher oxygen tension (20% O2) in cleavage rate (70.6% vs. 67.1., p1..8% vs. 1..3%, p1. selection does not have a significant effect on cleavage rate of NTEs expressing GFP. (ii) Nuclear maturation is greatly improved by prolonging IVM duration from 36 to 42 h, while no significant differences were observed for developmental potential of transgenic embryos. Thus IVM 42 h is the better choice in order to obtain maximum number of MII oocytes as recipients. (iii) Lower oxygen tension; higher oxygen tension in IVM have no significant effect on development of cloned embryos.

关键词： transgenic cloning, GFP, Pig, early development.

Purification of a Novel Antibacterial Short Peptide in Earthworm Eisenia foetida

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Acta Biochimica et Biophysica Sinica 2004年第4期36卷 297-302页

作者： Yan-Qin LIU1.2, Zhen-Jun SUN1., Chong wang1. Shi-Jie LI2, and Yu-Zhi LIU2 {1. of Resource and Environment science, china agricultural University, beijing 1.0094, china 2{1. of Animal science, Hebei agricultural University, Baoding 071.01. china college of Resource and Environment {1. China Agricultural UniversityBeijing 100094 China college of Animal {1. Hebei Agricultural UniversityBaoding 071001 China

A novel antimicrobial short peptide was purified from earthworm (Eisenia foetida) by a five-step protocol including ammonium sulfate precipitation, ultrafiltration, DE-52 ion exchange chromatography, Sephadex G-1. column chromatography, and C-1. reversed-phase HPLC techniques. The purified peptide was applied to the MALDI-TOF MS to determine the molecular mass and was also subjected to TOF MS-MS analysis to determine the amino acid sequence. As a result, a novel antibacterial peptide, named OEP31.1. was obtained, with the molecular mass of 51..8 Da and the sequence being “ACSAG”.

关键词： antibacterial peptide earthworm purification

Characterzation and separation of Al_(1.) species using gel-filtration chromatography

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science{1. Chemistry 2006年第4期49卷 326-331页

作者： CHU Yongbao1.2, gao Baoyu1. YUE Qinyan1. {1. Yan1.& {1. Shuguang1.1. School of Environmental science and Engineering, Shandong University, Jinan 2501.0, china 2. college of Material and Environment, Qingdao University of science and Technology, Qingdao 266042, china School of Environmental science and Engineering Shandong University Jinan China college of Material and Environment Qingdao University of Science and Technology Qingdao China

A polyaluminum chloride (PAC) sample was prepared using a slow alkalinetitration method. The Bio-Gel P-1.0 gel column chromatographic technique was used to separate andcharacterize the various forms of aluminum present in the prepared PAC solution. The effluents froma gel column were monitored using online chemical method: AI-Ferron timed complexationspectropho-tometry and by ^(27)Al nuclear magnetic resonance (NMR) spectroscopy. Effects ofdifferent experimental conditions such as eluent flow rate, ionic strength and pH on separation ofAl_(1.) were investigated. Experimental results indicated that molecule size exclusion was not theonly parameter affecting the column chromatographic separation efficiency of Al_(1.) but moleculecharge as well. Reducing the eluent flow rate, increasing the ionic strength and suitable pHresulted in increase in the separation efficiency. Experimental results clearly indicated that byvarying the experimental conditions, it is possible to produce pure Al_(1.) species using a gelcolumn chromatographic technique.

关键词： Al1. species, column chromatography, polyaluminum chloride (PAC), separation and purification.

Boundary conditions for the bending of a piezoelectric beam

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science{1.(Physics,Mechanics & Astronomy) 2008年第7期51卷 847-856页

作者： gao {1.1. XU SiPeng2 & ZHAO BaoSheng3 1.college of science, china agricultural University, beijing 1.0083, china 2 college of Engineering, Ocean University of china, Qingdao 266071. china 3 School of Mechanical Engineering, University of science and Technology Liaoning, Anshan 1.4044, china 1. college of {1. China Agricultural University Beijing 100083 China 2. college of Engineering Ocean University of China Qingdao 266071 China 3. School of Mechanical Engineering University of Science and Technology Liaoning Anshan 114044 China

For beam bending in transversely isotropic piezoelectric media, the reciprocal theorem and the general solution of piezoelasticity are applied in a novel way to obtain the appropriate stress and mixed boundary conditions accurate to all orders for the beam of general edge geometry and loadings. By generalizing the method developed by Gregory and Wan, a set of necessary conditions on the edge-data for the existence of a rapidly decaying solution is established. The prescribed edge-data of the beam must satisfy these conditions in order that they could generate a decaying state within the beam. When stress and mixed conditions are imposed on the beam edge, these decaying state conditions for the case of bending deformation of piezoelectric beam are derived explicitly. They are then used for the correct formulation of boundary conditions for the beam theory solution (or the interior solution). Besides, an analytical solution of elastic beam is formulated to verify validity of our boundary conditions. For the stress data, our boundary conditions coincide with those obtained in conventional forms of beam theories. More importantly, the appropriate boundary conditions with two sets of mixed edge-data are obtained for the first time.

关键词： boundary conditions beam bending piezoelectric media decaying states regular states

Mixed boundary conditions for piezoelectric plates

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science{1.(Physics,Mechanics & Astronomy) 2009年第5期52卷 755-761页

作者： gao yang 1 ,XU SiPeng 2 &ZHAO BaoSheng 3 1college of science,china agricultural University,beijing 1.0083,china 2college of Engineering,Ocean University of china,Qingdao 266071,china 3 School of Mechanical Engineering,University of science and Technology of Liaoning,Anshan 114044,china college of {1. China Agricultural University Beijing 100083 China college of Engineering Ocean University of China Qingdao 266071 China School of Mechanical Engineering University of Science and Technology of Liaoning Anshan 114044 China

For plate bending and stretching problems in piezoelectric materials,the reciprocal theorem and the general solution of piezoelasticity are applied in a novel way to obtain the appropriate mixed boundary conditions accurate to all order.A decay analysis technique is used to establish necessary conditions that the prescribed data on the edge of the plate must satisfy in order that it should generate a decaying state within the *** the case of axisymmetric bending and stretching of a circular plate,these decaying state conditions are obtained explicitly for the first time when the mixed conditions are imposed on the plate *** are then used for the correct formulation of boundary conditions for the interior solution.

关键词： boundary conditions piezoelectric plates mixed data bending problems stretching problems