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The relative generalized Hamming weight and the semilinear equivalence of codes

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science china(Information sciences) 2011年第4期54卷 787-794页

作者： LIU ZiHui 1 & WANG Jie 2 1 Department of Mathematics,beijing institute of technology,beijing 100081,china 2 school of Mathematical sciences,beijing University,beijing 100871,china Department of Mathematics Beijing Institute of Technology Beijing China school of Mathematical sciences Beijing University Beijing China

Certain equivalent conditions are given for the semilinear equivalence of linear codes by using the relative generalized Hamming weight and the value function.

关键词： value function semilinear equivalence support weight relative generalized Hamming weight

SEM in-situ Fatigue Observation on Crack Initiation and Growth from Inclusion in P/M Rene95 Superalloy

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Journal of University of science and technology beijing 2001年第3期8卷 195-197页

作者： Lina Zhang, Jianxin Dong, Xishan Xie Material science and Engineering school, University of science and technology beijing, beijing 100083, china Material science and Eng. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

A special designed experiment was conducted for observing crack initiation and growth in P/M Rene95 superalloy under tension-tension loading by self-made SEM in-situ fatigue loading stag. Several alumina inclusion particles exposed at the specimen surface were observed carefully. During fatigue test inclusions led to cracks initiation. The cracks can be formed by two mechanisms. Generally, the cracks nucleated at the interface between inclusion and matrix. Sometimes, cracks were also formed inside the inclusion. As the increase of cycles, some cracks at the interface between inclusion and matrix broadened and propagated along the direction about 45 degrees to the loading axis. On the other hand, the cracks inside the inclusion propagated in the inclusion and towards matrix.

关键词： inclusion P/M superalloy LCF SEM in-situ fatigue

Mass transfer coefficients in metallurgical reactors

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Journal of University of science and technology beijing 2003年第2期10卷 1-9页

作者： Ying QuMetallurgical Engineering school, University of science and technology beijing, beijing 100083, china Univ Sci & Technol beijing Met Engn Sch Beijing 100083 Peoples R China

An overview on the application and achievements of physico-mathematicalmodeling of metallurgical processes in china is briefly declared. The important role of coefficientsin model formulation is shown from our experience. The mass transfer coefficients of the slag-metalreactions and the gas-metal reactions are discussed referring to the flow conditions near theinterface. The influence of the surface-active species on the mass transfer and the interfacialreaction is also discussed briefly.

关键词： mass transfer modeling pyrometallurgy reaction engineering interfacial flow stirring power

Electro-Pulse on Improving Steel Ingot Solidification Structure

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International Journal of Minerals,Metallurgy and Materials 1999年第2期13卷 94-96页

作者： Yong Tang Jianzhong Wang Daqing Cang(Metallurgy school, University of science and technology beijing, beijing 100083, china) Metallurgy school University of Science and Technology Beijing Beijing 100083 China

Pulse Electric Discharging (PED) is a novel technique that can modify solidifying structure and reduce grain size. ItS effectsapplied to the high carbon liquid steel were presented here. The macrostructure and microstructure of the high carbon alloy steel werealso observed. Results show that (1 ) the length of columnar crystal at the edge of ingot without PED treatment is much longer than thatwith PED, and (2) the perlite lamellae of steel billets after deposed by PED are twisted and shortened. An explanation of those experimental results is given.

关键词： electro-pulse solidification structure steel ingot

Nickel multilayers and their effects on bend fatigue strength of leads

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Rare Metals 2004年第2期23卷 157-160页

作者： LIU Feihua WANG Zhanhua SHEN Zhuoshen school of Material science and Engineering, University of science and technology beijing, beijing 100083, china school of Material science and Engineering University of Science and Technology Beijing 北京 100083

Nickel is commonly coated on the outer leads for T8 metal package. The leadselectrodeposited by conventional dull or bright nickel over 5μm at direct current from Watt bathare hard to pass the bend fatigue test for three times. Nickel electrodeposited at multi waveformcurrent including direct current, single and double pulse from sulfamate bath can improve the bendfatigue strength of leads. Such nickel plating has a multilayer structure, its morphology ofsublayers can be clearly seen in its cross section with SEM. The electrochemical study shows thatthese sublayers have different corrosion potentials. The bend fatigue test of leads with suchplating for T8 metal package shows that the number of bend increases with the decrease of averagecurrent density of multi waveform, which can be attributed to the reduction of every sublayerthickness and the increase of layer numbers under the same condition of total thickness.

关键词： electroplating nickel multilayers multi waveform current bend fatiguestrength corrosion potential metal package

An Improved Artificial Neural Network Model for Predicting Silicon Content of Blast Furnace Hot Metal

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International Journal of Minerals,Metallurgy and Materials 2000年第4期14卷 269-272页

作者： Bin Yao, Tianjun Yang, Xiaojun Ning (Metallurgy school, University of science and technology beijing, beijing 100083, china) Metallurgy school University of Science and Technology Beijing Beijing 100083 China

Based on the skills of initializing weight distribution, adding an impulse in a neural network and expanding the ideal of plural weights, an artificial neural network model with three connection weights between one and another neural unit was established to predict silicon content of blast furnace hot metal. After the neural network was trained in the off-line state on the basis of a large number of practical data of a commercial blast furnace and making many learning patterns, satisfactory testing and simulating results of the model were obtained.

关键词： blast furnace silicon content neural network Metallurgy

Possibility of Reducing Formations of NO_x and SO_2 Simultaneously during Coal Combustion

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International Journal of Minerals,Metallurgy and Materials 2000年第3期14卷 165-169页

作者： Chunbao Xu, Shengli Wu, Daqiang Cang ( Metallurgy school, University of science and technology beijing, beijing 100083, china institute for Chemical Reaction science, Tohoku University, Japan) Metallurgy school University of Science and Technology Beijing Beijing 100083 China institute for Chemical Reaction science Tohoku University Japan

Comparing with other NO_x and SO_2 control technologies, in-bed reducing NO_x and SO_2 simultaneously during coal combustion may lower the investment and operation cost. However, there are several possible contradictions between the reduction of NO_x and the capture of SO2 during combustion: 1) CO rich atmosphere is favorable for the reduction of NO_x, whereas O_2 rich favorable for the capture of SO_2; 2) higher preheating temperature of coal is favorable for reducing NO_x, but unfavorable for reducing SO_2; 3) sulphation of some minerals may deactivate their catalytic effect on the reduction of NO_x. The attempts to eliminate such contradictions by coating coal granules with thin layer of monometallic oxides and mixed oxides were proposed. Ni_2O_3 and Fe_2O_3 showed high activity on NOx reduction and CaO and Cr_2O_3 showed good effect on sulfur capture. The mixed metallic oxides, e.g., Fe_2O_3NiO, etc., showed effective for both NO_x reduction and SO_2 retention. It is possible to in-bed reduce NO_x and SO_2 simultaneously if the adhering materials are properly chosen to be difunctional materials of both active catalysts for NO_x reduction reactions and better sorbents for SO_2 retention.

关键词： coal combustion purification of NO and SO catalyst sorbent

Solubility of Ba in Liquid Iron and Interaction Effect of the Third Elements

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International Journal of Minerals,Metallurgy and Materials 2000年第2期14卷 82-85页

作者： Bo Song Qiyong Han Chenming Zhang(Metallurgy school, University of science and technology beijing, beijing 100083, china) Metallurgy school University of Science and Technology Beijing Beijing 100083 China

Experiments were carried out at 1873 K in a double-temperature zone furnace using vapor pressure method. The equilibriumtests of bedum vapor with liquid iron were conducted in CaO crucibles sealed in a Mo chamber. As a result, the experiments obtainedthe relation between the dissolved content of Ba in liquid iron and the vapor pressure of Ba and the standard Gibbs energies for the re-actions Ba(g)=[Ba] and Ba(l)=[Ba].

关键词： Ba dissolution equilibrium liquid iron interaction parameter

Behaviors of fine bubbles in the shroud nozzle of ladle and tundish

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Journal of University of science and technology beijing 2003年第4期10卷 20-23页

作者： Yanping Boo, Jianhua Liu, and Baomei XuMetallurgical Engineering school, University of science and technology beijing, beijing 100083, china Metall. Eng. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

Fine bubbles will create when the inert gas is introduced to the high rapidsteel stream within the shroud nozzle between ladle and tundish. The collision and attachment amongthe bubbles and fine inclusions will promote the floatation efficiency of inclusions in the *** behaviors of the bubbles, such as the dispersion in shroud, coalescence and floatation intundish, are studied. The results show that the maximum sizes of the bubbles in the water and steelflow within the shroud in the length of 1.2 m are 0.70-1.44 mm and 1.53-3.16 mm respectively whenthe flow rates are 0.006-0.016 m^3/s; the terminal velocities of fine bubbles in the water andmolten steel within the tundish are 0.02-0.2 and 0.05-0.6 m/s.

关键词： fine bubbles shroud nozzle of the ladle flotation