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Electrochemical Characteristic of Decarburization Reaction

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International Journal of Minerals,Metallurgy and materials 1999年第1期13卷 27-30页

作者： Xionggang Lu Fushen Li Lifen Li Kouchih Chou (Applied Science school, university of Science and Technology {2.,{3.)(material Science and engineering school, Shanghai university, Shanghai 2.0072. china) Applied Science school University of Science and Technology Beijing Beijing 100083 China material Science and engineering {2. Shanghai University Shanghai 200072 China

The electrochemical mechanism of the reaction between Fe-C melts and CaO-SiO2.Al2.3.FeOx slag systems has been carried out. The experimental results suggest that the final content of carbon in melt increases as the partial oxygen pressure of gas decreases no matter whether there is electronic conductor or not. However, the final content of carbon in the system with electronic conductor is much lower than that without electronic conductor. It can be deduced that the transfer ability of oxygen in slag is dominated by electrons. When an electronic conductor exists, an easy pathway for the electrons is provided and the oxygen transfer rate is accelerated.

关键词： melt-slag reaction decarburization electrochemistry electronic conductor

Application of output feedback sliding mode control to active flutter suppression of two-dimensional airfoil

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Science china(Technological Sciences) 2010年第5期53卷 1338-1348页

作者： YANG Chao,SONG Chen,WU ZhiGang & XIE ChangChuan school of Aeronautic Science and engineering,{2. {3. of aeronautics & astronautics,{2. 100191,china 1. school of Aeronautic Science and engineering Beijing University of Aeronautics & Astronautics Beijing 100191 China

The effectiveness of the sliding mode control(SMC) method for active flutter suppression(AFS) and the issues concerning control system discretization and control input constraints were studied using a typical two-dimensional *** airfoil has a trailing-edge flap for flutter *** aeroelastic system involves a two-degrees-of-freedom motion(pitch and plunge),and the equations were constructed by utilizing quasi-steady aerodynamic *** control system,designed by the output feedback SMC method,was incorporated to suppress the pitch-plunge ***,the system discretization and the flap deflection constraints were ***,a classical Runge-Kutta(RK) algorithm was utilized for numerical *** results indicated that the close-loop system with the SMC system could be stable at a speed above the flutter ***,when the flap deflection limits are reached,the close-loop system with the simple discretized control system loses ***,control compensation developed by theoretical analysis was proposed to make the system stable *** parameter perturbations and the time delay effects were also discussed in this paper.

关键词： aeroelasticity flutter airfoil sliding mode control output feedback control

Microstructure Study on Semi-solid 60Si2.n during Compressing

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Journal of university of Science and Technology beijing 2001年第2期8卷 115-118页

作者： Yonglin Kang, Xiongfei Yang, Renbo Song, Weimin Mao, Maosheng Yang (material Science & engineering {2., {3. of Science and Technology beijing, beijing 100083. china) material Sci. and Eng. school University of Science and Technology Beijing 100083 China

The microstructure behavior and deformation mechanism of semi-solid 60Si2.n fabricated by electromagnetic stirring under different deformation conditions during thixoforming are studied by means of Gleeble-1500 thermal-strain-stress simulator. The micro- structure of deformed 60Si2.n and that of the non-deformed are compared. The results show that the grain size within deformation zone decreases as the amount of deformation increases or deformation temperature decreases, but deformation fate has small effect on grain size when the rate is very low. Besides, there is a critical amount of deformation to reduce grain size. These results offer theoretical and experimental basis for further producing semi-solid material with high melting temperature and direct forming of semi-solid slurry.

关键词： semi-solid microstructure grain size segregation, reduction

Preparation and High Temperature Oxidation Properties of Micro-crystalline MGH754 ODS Alloy Coatings

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Journal of university of Science and Technology beijing 2001年第1期8卷 28-34页

作者： Huibub Qi Hongmei Pang Yedong He Deren Wang Wei Gao material Seience and engineering {2., {3. of Science and Technology beijing, beijing 100083. china Department of Chemical and material Engineeing, the {3. of Auckland, New Zealand Univ Sci & Technol beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China Univ Auckland Dept Chem & Mat Engn Auckland 1 New Zealand

A special coating technique, electro-spark deposition (ESD), was developed to produce micro-crystalline ODS MGH754 alloy coatings on a commercial 1Cr18Ni9Ti stainless steel and a cast Ni2.Cr alloy substrates. The coatings have a very fine grain structure and metallurgical bonding with the substrates. The isothermal oxidation tests at 1000 degreesC in air showed that the micro-crystalline ODS alloy coatings had a much reduced oxidation rate and improved scale spallation resistance compared with the uncoated alloys. The selective oxidation of Cr was greatly promoted to form protective and continuous Cr2.3.scales on the alloy surface. Micro-crystallization and oxide dispersions have synergistic effects on the improvement of oxidation resistance. The beneficial effects were discussed based on the experimental results.

关键词： electro-spark deposition (ESD) ODS coating oxidation

Effect of electric field,stress and environment on delayed fracture of a PZT-5 ferroelectric ceramic

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Science china(Physics,Mechanics & Astronomy) 2005年第1期48卷 89-100页

作者： WANG Yi, SU Yanjing, CHU Wuyang & QIAO Lijie Department of material Physics, university of Science and Technology {2.,{3. school of Mechanic and Electric Control engineering, {2. Jiaotong university, {2. 100044, china 1. Department of material Physics University of Science and Technology Beijing 100083 Beijing China 2. school of Mechanic and Electric Control engineering Beijing Jiaotong University 100044 Beijing China

The combined effect of electric and mechanical loading on fracture of a PZT-5 ferroelectric ceramic in silicone oil has been investigated using a single edge notched specimen. The results show that the fracture toughness and the threshold stress intensity factor of delayed fracture in silicone oil, i.e. stress corrosion cracking, decrease linearly with the increasing applied electric field, either positive or negative. For the PZT-5 ferroelectric ceramics, delayed fracture in silicone oil under sustained positive or negative field can occur, and the threshold field for delayed fracture under sustained positive or negative field decreases linearly with applied stress intensity factor. The combined effect of electric and mechanical loading on delayed fracture in silicone oil includes fieldenhancing delayed fracture under sustained load and stress-enhancing delayed fracture in silicone oil under sustained field.

关键词： PZT-5 ferroelectric ceramics, fracture toughness, delayed fracture under sustained load, delayedfracture under sustained electric field.

A Special TMCP Used to Develop a 800MPa Grade HSLA Steel

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Journal of university of Science and Technology beijing 2001年第3期8卷 224-228页

作者： Chengjia Shang,Xuemin Wang, Xinlai He, Shanwu Yang, Yi Yuan material Science and engineering {2., {3. of Science and Technology beijing, beijing, 100083. china Univ Sci & Technol beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China

The effect of relaxation after finished rolling on structures and properties of four microalloyed steel with different content of Nb and Ti was investigated. By alloy designing and control rolling + relaxation-precipitation-control phase trail storm ati on (RPC) process, a new 800 MPa grade HSLA plate steel could be obtained, the microstructure is composite ultra-fine lath bainite/martensite. The tempering process and mechanical properties of this kind of HSLA steel were investigated. The yield strength can achieve 800 MPa, and the ductility and impact toughness is satisfied.

关键词： HSLA steel microstructure and mechanical properties TMCP (thermomechanical control process) RPC

Stability of Ultra-fine Microstructures during Tempering

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Journal of university of Science and Technology beijing 2001年第2期8卷 119-122页

作者： Shanwu Yang, Chengjia Shang,Xinlai He, Xuemin Wang, Yi Yuan (material Science and engineering {2., {3. of Science and Technology beijing, beijing 100083. china) Univ Sci & Technol beijing Mat Sci & Engn Sch Beijing 100083 Peoples R China

The stability of ultra-fine microstructure during tempering at 650 degreesC was investigated on a Nb-containing steel. The steel had undergone 5 passes controlled rolling, then was relaxed lair cooled) to 73. degreesC: and cooled in water. The evolution of microstructure was that, in early stage of tempering, no obvious change was detected by means of optical microscopy while dislocation cells were formed inside bainitic laths. With further tempering, bainitic laths started to coalesce in some regions. Finally, polygonal ferrite was formed while hardness decreased dramatically. Some samples taken from the same primary plate were reheated at 93. degreesC for 0.5 h followed by quenching into water before tempering. Despite their lower original hardness, the reheated samples softened Faster during tempering. Ferrite was quickly formed in the reheated samples. These results indicate that the evolution of microstructures towards equilibrium during tempering of the steel is mainly determined by whether dislocations are pinned rather than the dislocation density.

关键词： microalloyed steel bainite tempering

Effects of binders on the performance of electric double-layer capacitors of carbon nanotube electrodes

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Progress in Natural Science:materials International 2005年第5期15卷 453-457页

作者： LI Chensha1*, WANG Dazhi1, ZHANG Baoyou2. WANG Xiaofeng1, CAO Maosheng3. and LIANG Ji1(1. Department of Mechanical engineering, Tsinghua {2., beijing 100084, {3. 2. Center for Analysis and Measurement, Harbin Institute of Technology, Harbin 150001, {3. 3. school of material Science and engineering, Tsinghua {2., beijing 100084, {3.) Department of Mechanical engineering Tsinghua University Beijing 100084 China Center for Analysis and Measurement Harbin Institute of Technology Harbin 150001 China school of material Science and {2. Tsinghua University Beijing 100084 China

Polarizable electrodes of electric double layer capacitor (EDLCs) were made from carbon nanotubes. Effects of different binders, which are phenolic resin (PF) and polytetrafluoroethylene (PTFE), on the properties of polarizable electrodes are studied. Results indicate that the microstructure, pore size distribution and specific capacitance of the electrodes with PTFE binder are superior to those electrodes with PF binder after carbonization. The suitable binder (PTFE) for carbon nanotubes electrodes is proposed.

关键词： carbon nanotubes electric double-layer capacitors phenolic resin polytetrafluoroethylene.

Bursting of Morris-Lecar neuronal model with current-feedback control

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Science china(Technological Sciences) 2009年第3期52卷 771-781页

作者： DUAN LiXia1, LU QiShao2.& CHENG DaiZhan3.1 College of Science, North china {2. of Technology, beijing 100144, china 2.school of Science, beijing university of aeronautics and astronautics, beijing 100191, china 3.Institute of Systems Science, Chinese Academy of Sciences, beijing 100190, china College of Science North China University of Technology Beijing 100144 China school of Science Beijing University of Aeronautics and Astronautics Beijing 100191 China Institute of Systems Science Chinese Academy of Sciences Beijing 100190 China

The Morris-Lecar (ML) neuronal model with current-feedback control is considered as a typical fast-slow dynamical system to study the combined influences of the reversal potential VCa of Ca2. and the feedback current I on the generation and transition of different bursting oscillations. Two-parameter bifurcation analysis of the fast subsystem is performed in the parameter (I, VCa)-plane at first. Three important codimension-2.bifurcation points and some codimension-1 bifurcation curves are obtained which enable one to determine the parameter regions for different types of bursting. Next, we further divide the control parameter (V0, VCa)-plane into five different bursting regions, namely, the "fold/fold" bursting region R1, the "fold/Hopf" bursting region R2. the "fold/homoclinic" bursting region R3. the "subHopf/homoclinic" bursting region R4 and the "subHopf/subHopf" bursting region R5, as well as a silence region R6. Codimension-1 and -2.bifurcations are responsible for explanation of transition mechanisms between different types of bursting. The results are instructive for further understanding the dynamical behavior and mechanisms of complex firing activities and information processing in biological nervous systems.

关键词： neuron bursting bifurcation fast-slow dynamics analysis codimension