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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. china 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 {1. {1. 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 1.0871. 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

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.

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

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.

2D Ca/Nb-based perovskite oxide with Ta doping as highly efficient H_(2)O_(2)synthesis catalyst

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Nano Research 2024年第6期17卷 4934-4942页

作者： Xingchen yang yang gao Xiaohui Xu Wenqiang Xu Denghui wang Bin Luo Dong Liu Tao Liang Bin wang CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and TechnologyBeijing 100190China University of Chinese Academy of sciences Beijing 100049China Nanomaterials Centre School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnologythe University of QueenslandSt LuciaQLD 4072Australia State Key Laboratory of Organic–Inorganic Composites College of Chemical EngineeringCollege of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029China Hangzhou Institute for Advanced Study University of Chinese Academy of SciencesHangzhou 310024China State Key Lab of Silicon Materials Zhejiang UniversityHangzhou 310027China

Perovskite oxides(POs)are emerging as a class of highly efficient catalysts for reducing oxygen to H_(2)*** a rich variety of POs-based catalysts have been developed by tuning the complex composition,a highly efficient PO catalyst that is able to alter the reaction pathway from a 4e−process to a 2e−process for H_(2)O_(2)production has rarely been *** modified the structure and composition of a Ca-and Nb-based PO material by realizing a uniform two-dimensional(2D)morphology and varied Ta doping,resulting in the 2D Ca_(2)Nb_(3−x)Ta_(x)O_(1.)−(x=0,0.5,1.and 1.5)monolayer *** obtained catalysts exhibit a dominant 2e−pathway and show exceptional H_(2)O_(2)production *** typical Ca_(2)Nb_(2.5)Ta_(0.5)O_(1.)−nanoflakes showed an onset potential of 0.735 V *** hydrogen electrode(RHE),a remarkably high selectivity over 95%across a wide range of 0.3-0.7 V,an impressively high Faradaic efficiency of 94%,and a notable H_(2)O_(2)productivity of 1.71.mmol·gcat^(−1.·h^(−1..These findings highlight the great potential of 2D perovskite oxide nanoflakes as advanced electrocatalysts for 2e−oxygen reduction reaction.

关键词： perovskite oxide H_(2)O_(2) two-electron oxygen reduction reaction catalyst Ca_(2)Nb_(3-x)Ta_(x)O_(1.)-nanoflakes

Suitability evaluation for land reclamation in mining area:A case study of gaoqiao bauxite mine

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中国有色金属学会会刊：英文版 2011年第S3期21卷 506-515页

作者： wang Shi-dong1. 2, LIU Chang-hua2, ZHANG He-bing2 1. {1. of Resources science and Technology, beijing Normal University, beijing 1.0875, china 2. School of Surveying and Land Information Engineering, Henan Polytechnic University, Jiaozuo 454000, china [a] college of Resources {1. and Technology Beijing Normal University Beijing 100875 China [b] School of Surveying and Land Information Engineering Henan Polytechnic University Jiaozuo 454000 China

Suitability evaluation plays an important role in land reclamation because the choice of evaluation methods affects the accuracy and objectivity of the suitability evaluation results. Furthermore, it influences the decision-making related to land reclamation. An improved method, which is called limit comprehensive conditions method, was developed after different suitability evaluation methods were studied. Based on this method, the reclaimed land of the gaoqiao bauxite mining area was evaluated. The gaoqiao mining area was divided into seven evaluation units that were evaluated respectively by selecting evaluation factors and establishing grade standards. The results show that the proposed method is more applicable and easier to handle. Moreover, its evaluation results are more scientific compared with the traditional evaluation methods. The improved method can be beneficial to the rapid monitoring and the effective management of reclaimed land in the opencast mine area.

关键词： mining area land reclamation suitability evaluation gaoqiao bauxite mine

Magnetron sputtering synthesis of large area well-ordered boron nanowire arrays

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science {1.(Physics,Mechanics & Astronomy) 2004年第4期47卷 403-415页

作者： CAO Limin1.2, ZHANG Ze2 & wang Wenkui1.2 1. Key Laboratory of Metastable Materials {1. and Technology and college of Materials {1. and Engineering, Yanshan University, Qinhuangdao 066004, china 2. Institute of Physics, Chinese Academy of {1.s, beijing 1.0080, china 1. Key Laboratory of Metastable Materials science and Technology and {1. of Materials science and Engineering Yanshan University 066004 Qinhuangdao China 2. Institute of Physics Chinese Academy of Sciences 100080 Beijing China

One-dimensionally nanostructured materials, such as nanowires and nanotubes, are the smallest dimensional structures for efficient transport of electrons and excitons, and are therefore critical building blocks for nanoscale electronic and mechanical devices. In this paper, boron nanowires with uniform diameters from 20 to 80 nm were synthesized by radio-frequency magnetron sputtering of pure boron powder and B2O3 powder mixtures in argon atmosphere. The boron nanowires produced stand vertically on the substrate surface to form well-ordered arrays over large areas with self- organized arrangements without involvement of any template and patterned catalyst. The high-density boron nanowires are parallel to each other and well distributed, forming highly ordered and uniform arrays. A more interesting and unique feature of the boron nanowires is that most of their tips are flat rather than hemispherical in morphologies. Detailed studies on its structure and composition indicate that boron nanowires are amorphous. Boron nanowire appears as a new member in the family of one-dimensional nanostructures. Considering the unique properties of boron-rich solids and other nanostructures, it is reasonable to expect that the boron nanowires will display some exceptional and interesting properties. A vapor-cluster-solid (VCS) mechanism was proposed to explain the growth of boron nanowires based on our experimental observations.

关键词： boron nanowires, magnetron sputtering, arrays, self-assembly.

Synthesis and thermodynamic analysis of nano-La2O3

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Progress in Natural science:Materials International 2007年第7期17卷 838-844页

作者： Liu Lili~(1.2) Tang Jie~2 Li Yuxiang~1.Zhang Mei~(1.*) wang Xidong~(1.3) (1.Department of Physical Chemistry,University of {1. and Technology beijing,beijing 1.0083.china 2.National Institute for Materials {1.,Segen 1.2-1.Tsukuba 305-0047,Japan 3.college of Engineering,beijing University,beijing 1.0871.china) [a]Department of Physical Chemistry University of Science and Technology Beijing Beijing China [b]National Institute Materials science Tsukuba Jpan [c]college of Engineering Beijing University Beijing China

The thermodynamic parameters of La（NO3）3and La（OH）3are evaluated and the thermodynamics of nano-La2O3syn- thetic process is *** the base of thermodynamic analysis,La2O3nano-powders are prepared by the sol-gel method and the experi- ment scheme is designed by an orthogonal *** dry-gelatin is analyzed with differential thermal analysis/thermo-gravimetric analy- sis（TGA-DTA）and X-ray diffraction *** microstructure of nano-La2O3powders is observed by transmission dectron micro- *** synthetic parameters affecting the average grain size and dispersivity of nano-La2O3particles are experimentally examined and *** the results indicate that nano-La2O3particles well-dispersed are obtained and the average grain size is in the range of 20—50 nm.

关键词： nano-La2O3 sol-gel thermodynamic analysis