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Effects of Na/K ratio on the phase structure and electrical properties of Na_xK_(1-x)NbO_3 lead-free piezoelectric ceramics

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Rare Metals 2010年第2期29卷 220-225页

作者： ZHANG Qian, ZHANG Boping, Li Haitao, and SHANG Pengpeng school of Materials Science and engineering, university of Science and Technology beijing, beijing 100083, china school of Materials Science and engineering University of Science and Technology Beijing

Lead-free piezoelectric NaxK1-xNbO3（x = 0.3-0.8）（NKN） ceramics were fabricated by normal sintering at 1060°C for 2 *** and electrical properties of the ceramics were investigated with a special emphasis on the influence of Na *** grain size of the produced dense ceramic was decreased by increasing Na content.A discontinuous change in the space distance was found at the composition close to Na0.7K0.3NbO3 ceramic, which indicates the presence of a transitional composition between two different orthorhombic phases, which is similar to the behavior of morphotropic phase boundary（MPB） in NaxK1-xNbO3 *** MPB-like behavior contributes to the enhanced piezoelectric coefficient d33 of 122 pC/N, planar-mode electromechanical coupling coefficient kP of 28.6%, and dielectric constant εr of 703, respectively for the Na0.7K0.3NbO3 *** temperature TC and the transitional temperature TO-T from orthorhombic to tetragonal phase are observed at around 420°C and 200°C, respectively.

关键词： lead-free piezoelectric ceramics NKN sintering morphotropic phase boundary(MPB)

Process optimization of reaction of acid leaching residue of asbestos tailing and sodium hydroxide aqueous solution

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Science china(Technological Sciences) 2009年第1期52卷 204-209页

作者： DU GaoXiang1,3, ZHENG ShuiLin2 & DING Hao1 1 school of Materials Science and Technology, china university of Geosciences (beijing), beijing, 100083, china 2 school of Chemical and Environment engineering, china university of Mining and Technology (beijing), beijing 100083, china 3 Hebei Qinghe Refractory Group Co. Ltd., Xingtai 054804, china 1. school of Materials Science and Technology China University of Geosciences (Beijing) Beijing 100083 China 3. Hebei Qinghe Refractory Group Co. Ltd. Xingtai 054804 China 2. school of Chemical and Environment engineering China University of Mining and Technology (Beijing) Beijing 100083 China

Silica is the major component of the acid leaching residue of asbestos tailing. The waterglass solution can be prepared by the reaction of the residue with sodium hydroxide aqueous solution. Compared to the high temperature reaction method, this process is environmental friendly and low cost. In this paper, the reaction process of the residue and the sodium hydroxide aqueous solution is optimized. The optimum reaction process parameters are as follows: the usage of sodium hydroxide is 26.4 g/100 g acid leaching residue, the reaction temperature is 90℃, the reaction time is 1 h, and the ratio of the liquid/solid is 2.0. The significance sequence of the process parameters to the alkali leaching reaction effect is the usage of sodium hydroxide > the ratio of the liquid/solid > the reaction time > the reaction temperature. The significance sequence to the leaching ratio of SiO2 is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. The significance sequence to the modulus of the sodium silicate is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. Under the optimum conditions, the leaching ratio of the SiO2 is 77.5%, and the modulus of the sodium silicate is 3.15. The XRD analysis result indicates that the major components of the alkali leaching residue are serpentine, talc, quartz and some albite.

关键词： asbestos tailing acid leaching residue sodium hydroxide process optimization

Preconditioned pseudo-compressibility methods for incompressible Navier-Stokes equations

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中国科学：物理学、力学、天文学英文版 2010年第11期53卷 2090-2102页

作者： QIAN ZhanSen ,ZHANG JingBai & LI ChunXuan school of Aeronautics Science and engineering,beihang university,beijing 100191,china 1. school of Aeronautics Science and engineering Beihang University Beijing 100191 China

This paper investigates the pseudo-compressibility method for the incompressible Navier-Stokes equations and the preconditioning technique for accelerating the time marching for stiff hyperbolic equations,and derives and presents the eigenvalues and eigenvectors of the Jacobian matrix of the preconditioned pseudo-compressible Navier-Stokes equations in generally cur-vilinear *** on the finite difference discretization the cored for efficiently solving incompressible flows numerically is *** reliability of the procedures is demonstrated by the application to the inviscid flow past a circular cylinder,the laminar flow over a flat plate,and steady low Reynolds number viscous incompressible flows past a circular *** is found that the solutions to the present algorithm are in good agreement with the exact solutions or experimental *** effects of the pseudo-compressibility factor and the parameter brought by preconditioning in convergence characteristics of the solution are investigated *** results show that the upwind Roe’s scheme is superior to the second order central scheme,that the convergence rate of the pseudo-compressibility method can be effectively improved by preconditioning and that the self-adaptive pseudo-compressibility factor can modify the numerical convergence rate significantly compared to the constant form,without doing artificial tuning depending on the specific flow *** validation is also performed by numerical simulations of unsteady low Reynolds number viscous incompressible flows past a circular *** results are also found in good agreement with the existing numerical results or experimental data.

关键词： pseudo-compressibility method preconditioning upwind scheme incompressible flow Navier-Stokes equations

Crawling gait realization of the mini-modular climbing caterpillar robot

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Progress in Natural Science:Materials International 2009年第12期19卷 1821-1829页

作者： Wei Wang~(a,*),Kun Wang~a,Houxiang Zhang~b a Robotics Institute,school of mechanical engineering and automation,beihang university,beijing 100083,china b TAMS,Department of Computer Science,university of Hamburg,Vogt-Koelln-Strasse 30,Hamburg 22527,Germany [a]Robotics Institute School of Mechanical Engineering and Automation Beihang University Beijing 100083 China [b]TAMS Department of Computer Science University of Hamburg Vogt-Koelln-Strasse 30 Hamburg 22527 Germany

The concept of a modular climbing caterpillar robot is inspired by the kinematics of real *** typical kinematics models and gaits are investigated based on the crawling motion of the inchworm and the tobacco *** to the fixed constraints between the suckers and the wall,the gait of a caterpillar robot engages a changing kinematic chain which is from an open chain to a closed chain,and then to an open chain in *** the open chain periods,an unsymmetrical phase method(UPM) is used to ensure the reliable attachment of the passive suckers to the *** the closed-chain state,a four-link kinematics model is adopted to fulfill the fixed *** combining the two methods together,the complete joint control trajectories are acquired for a modular caterpillar robot with seven *** last,on-site tests confirm the proposed principles and the validity of the climbing gait.

关键词： Climbing robot Modular Biologically inspired Gait

CONVERSE REASONING FOR FULL DEPRESSION-FEATURE MODEL AND PROCESS

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Chinese Journal of mechanical engineering 2003年第2期16卷 160-162页

作者： Shen XiaohongLiu XuanYu FangfangZhang LeiFeng TaoCollege of mechanical engineering and automation,beijing Technology and Business university, beijing 100037, china College of mechanical engineering and automation Beijing Technology and Business University 北京 100037

A new approach, namely, 'defining protrusion-feature withdepression-parameter' is advanced, which focuses on the shortcomings of protrusion-featurealteration method; The full depression-feature model is built up, and a basic converse reasoningiterative algorithm for machining process is given. The detailed examination has been implemented onthe feature-based modeling system for light industry product (QJFMS) and the converse reasoning onfixture-based machining process is achieved.

关键词： protrusion-feature full depression-feature model reasoning iterativealgorithm

Application of Single Neuron Adaptive PID Regulators with Auto-tuning Gain in Industrial Parameter(Pressure)Closed-loop Process Control Systems

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International Journal of Minerals,Metallurgy and Materials 1999年第2期13卷 152-153页

作者： Shaoyuan Sun Huade Li Bin Qian Jianping Wei(Information engineering school, university of Science and Technology beijing, beijing 100083, china) Information engineering school University of Science and Technology Beijing Beijing 100083 China

A type of single neuron adaptive PID regulator with auto-tuning gain is proposed and applied to the work control of fans, waterpumps and air-pressers etc. in Handan Iron & Steel Compel china. The robusthess of induStr... 详细信息

关键词： single neuron gain adaptiVe PID regulator pressure closed-loop control

Cutting Performance and Mechanism of RE Carbide Tools

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Rare Metals 2001年第3期20卷 197-201页

作者： Jianbing Cheng, Yufang Wu, Qixun Yu 1) Department of mechanical engineering, beijing Technology and Business university, beijing 100037, china 2) College of mechanical engineering and automation, beijing Institute of Technology beijing 100081, china beijing Technol & Business Univ Dept Mech Engn Beijing 100037 Peoples R China beijing Inst Technol Coll Mech Engn & Automat Beijing 100081 Peoples R China

The research of rare earth elements (RE), added into cemented carbide tools, is one of the recent developments of new types of tool materials in china. Systematic experiments about RE carbides YG8R. (K30), YT14R (P20) and, YW1R (M10) were made to study on the cutting performance in comparison with non-RE carbides YG8, YT14 and YW1. The cutting experiments were as follows: tool life, cutting force, tool-chip friction coefficient and interrupted machining. The action of RE on the carbide materials and the cutting mechanism of the RE carbide tools in the cutting process were verified with the aid of SEM and energy spectrum analysis. Experimental results show that the RE carbide tools have a good overall performance.

关键词： rare earth elements cemented carbide tool cutting performance cutting mechanism

Dissolving of Nb and Ti carbonitride precipitates in microalloyed steels

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Journal of university of Science and Technology beijing 2003年第5期10卷 78-80页

作者： Wenjin Nie, Shanwu Yang, Shaoqiang Yuan, and Xinlai HeMaterials Science and engineering school, university of Science and Technology beijing, beijing 100083, china Materials Science and engineering school University of Science and Technology Beijing Beijing 100083 China

The dissolving behaviour of Nb and Ti carbonitride precipitates inmicroalloyed steels during isothermal holding at 1300℃ was investigated by Transmission electronmicroscopy (TEM) and energy dispersion x-ray spectrum (EDX). It was found that all precipitates inNb-Ti microalloyed steel are (Nb, Ti)(C, N). With holding time increasing, the atomic ratio of Nb/Tiin precipitates decrease gradually. These precipitates still existe even after holding for 48 h at1300℃ while Nb(C, N) precipitates dissolve away in Nb microalloyed steel only after 4 h at the sametemperature. These results show that formation and thermostability of precipitates are considerablyinfluenced by interaction between Nb and Ti.

关键词： dissolving (Nb, Ti)(C, N) TEM EDX

The Lightweight Design of Low RCS Pylon Based on Structural Bionics

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Journal of Bionic engineering 2010年第2期7卷 182-190页

作者： Hongjie Jiao,Yidu Zhang,Wuyi Chen mechanical engineering Design Centre,beihang university,beijing 100191,P.R.china [a] mechanical engineering Design Centre Beihang University Beijing 100191 P. R. China

A concept of Specific Structure Efficiency (SSE) was proposed that can be used in the lightweight effect evaluation *** main procedures of bionic structure design were introduced *** parameter relationship betweenhollow stem of plant and the minimum weight was deduced in *** order to improve SSE of pylons, the structural characteristicsof hollow stem were investigated and *** pylon was designed based on analogous biological *** finite element method based simulation, the displacements and stresses in the bionic pylon were comparedwith those of the conventional *** show that the SSE of bionic pylon is improved ***, dynamic andelectromagnetism tests were carried out on conventional and bionic *** weight, stress, displacement and Radar CrossSection (RCS) of both pylons were *** results illustrate that the SSE of bionic pylon is markedly improvedthat specific strength efficiency and specific stiffness efficiency of bionic pylon are increased by 52.9% and 43.6% *** RCS of bionic pylon is reduced significantly.

关键词： lightweight design specific structure efficiency low RCS pylon bionic structure