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Dependence of Magnetic Properties and Microstructure of Ni_(81)Fe_(19) Film on Base Vacuum and Sputtering Pressure

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Journal of University of Science and Technology Beijing 2002年第1期9卷 45-47页

作者： HongchenZhao HongSi 等 MaterialsScienceandEngineeringSchool UniversityofScienceandTechnologyBeijing100083China CentralIronandSteelResearchInstitute Beijing100081China

The Ni_81Fe_19 / Ta films with different NiFe thickness were prepared atdifferent base vacuums and sputtering pressures. The results of magnetic measurement and atomicforce microscope (AFM) showed that the films prepared at higher base vacuum and lower sputteringpressure had larger DELTAR/R. The reason should be that higher base vacuum and lower sputteringpressure introduce larger grainsize and lower surface roughness, which will weaken the scattering ofelectrons, reduce the resistance R, and increase DELTAR/R.

关键词： NiFe film anisotropic magnetoresistance surface roughness grain-size

Atomic—Scale Kinetic Monte Carlo Simulation of {100}—Oriented Diamond Film Growth in C—H and C—H—CI Systems by Chemical Vapour Deposition

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Chinese Physics Letters 2002年第7期19卷 1019-1020页

作者：安希忠张禹等 SchoolofMaterialsScienceandEngineering UniversityofScienceandTechnologyBeijingBeijing100083 SchoolofAppliedScience UniversityofScienceandTechnologyBeijingBeijing100083

We simulate the {100} -oriented diamond film growth of chemical vapour deposition (CVD) under different models in C-H and C-H-Cl systems in an atomic scale by using the revised kinetic Monte Carlo method. The simulation results show that: (1) the CVD diamond film growth in the C-H system is suitable for high substrate temperature, and the film surface roughness is very coarse; (2) the CVD diamond film can grow in the C-H-Cl system either at high temperature or at low temperature, and the film quality is outstanding; (3) atomic Cl takes an active role for the growth of diamond film, especially at low temperatures. The concentration of atomic Cl should be controlled in a proper range.

关键词： Chemical vapor deposition

Effect of hydrogen attack on acoustic emission behavior of low carbon steel

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Journal of University of Science and Technology Beijing 2002年第2期9卷 130-134页

作者： XiaogangLi ChaofangDong 等 MaterialsscienceandEngineeringSchool universityofScienceandTechnologyBeijingBeijing100083China MaterialsscienceandEngineeringSchool universityofScienceandTechnologyBeijingBeijin

In order to investigate the effect of hydrogen attack degree on acoustic emission(AE) behavior of low carbon steel during tensiling, specimens made of Low carbon steel was exposed to hydrogen gas of 18 MPa at 450 and 500℃ for 240, 480 and 720 h respectively. Experimental results show that with increase of the hydrogen attack degree, the totally AE activity decreases during tensiling. In addition, the count of AE signals with high amplitude for the specimens with hydrogen attack keeps a constant which is less than that without hydrogen attack. It is concluded that AE signals originate in the specimens with hydrogen attack from intergranular fracture induced by methane blisterings or/and microcracks on grain boundaries.

关键词： low carbon steel hydrogen attack acoustic emission

Grain refinement of low carbon steel produced by CSP process

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Journal of University of Science and Technology Beijing 2004年第2期11卷 133-137页

作者： XiangdongHuo DeluLiu YuanliWang NanjingChen YonglinKang JieFu MaterialsScienceandEngineeringSchool UniversityofScienceandTechnologyBeijing100083BeijingChina MetallurgicalandEcologicalEngineeringSchool UniversityofScienceandTechnologyBeijing100083BeijingChina

In comparison with conventional production for hot strips, compact strip production (CSP) brings about some new micro-structural phenomena. Investigations were carried out to clarify the grain refinement mechanism of low carbon steel strips produced by the EAF-CSP process. Samples, obtained from the same rolling stock during continuous rolling, were examined through SEM, TEM and XEDS. Thin slabs have a dominant columnar structure and the spacing of the secondary dendrite arms ranges from 90 to -125 μm. The average grain sizes for the central area of the samples from the 1st to 6th pass are 41.6, 25.2, 21.4, 20.2, 13.1, 6.7 μm, respectively. Large number of nanometer oxide and sulfide have been found in the low carbon steel produced by the CSP process. The grain refinement mechanism can be summarized as follows: finer solidification structure of the thin slab; austenite recrystalliza-tion at higher temperature and stain accumulation at lower temperature caused by the great reduction of single rolling pass during continuous rolling; nano-scaled precipitates of sulfide and oxide which drag grain boundaries of austenite or ferrite to prevent the grain coarsening.

关键词： low carbon steel hot strips CSP process microstructure evolution grain refinement

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Journal of University of Science and Technology Beijing 2002年第2期9卷 104-106页

作者： LiancunZheng XinxinZhang 等 AppliedscienceSchool universityofScienceandTechnologyBeijingBeijing100083China MechanicalEngineeringSchool UniversityofScienceandTechnologyBeijingBeijing100083China

A suitable similarity transformation is introduced to reduce the laminarboundary layer equations of power law fluids to a class of singular nonlinear two-point boundaryvalue problems. The kin friction and shear stress distributions for boundary layer flow over amoving flat plate are investigated by utilizing the shooting technique. Results indicate that foreach fixed value of the power law exponent n or the velocity ratio parameter xi, the skin frictionand shear stress decrease with the increasing of n or xi respectively.

关键词： boundary layer skin friction similarity solution shooting technique

Research on viral dynamic models of hepatitis B virus infection

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Journal of University of Science and Technology Beijing 2004年第6期11卷 572-576页

作者： LequanMin XisongDong AppliedScienceSchool UniversityofScienceandTechnologyBeijingBeijing100083China／／InformationEngineeringSchoolUniversityofScienceandTechnologyBeijingBeijing100083China InformationEngineeringSchool UniversityofScienceandTechnologyBeijingBeijing100083China

A mathematical model with cytotoxic cells of hepatitis B virus (HBV)infection is set up based on a basic model of virus dynamics without cytotoxic cells andexperimental observation of anti-viral drag therapy for HBV infection patients. A quantitativeanalysis of dynamic behaviors shows that the model has three kinds of equilibrium points, whichrepresent the patient's complete recovery without immune ability, complete recovery with immuneability, and HBV persistent infection at the end of the treatment with drag lamivudine,respectively. Our model may provide possible quantitative interpretations for the treatments ofchronic HBV infections with the drag lamivudine, in particularly explain why the plasma virus ofNowak et al. 's patients turnover the original level after stopping the lamivudine treatment.

关键词： mathematical model liver hepatitis B virus lamivudine treatment equilibrium point stability treatment time numeric simulation

Experimental Study and Analysis on Performance and Dedusting Efficiency of Frothing Generator

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Journal of University of Science and Technology Beijing 2002年第1期9卷 5-8页

作者： ZhonganJiang CuifengDu 等 CivilandEnvironmentalEngineeringSchool UniversityofScienceandTechnologyBeijingBeijing100083China CivilandEnvironmentalEngineeringSchool UniversityofScienceandTechnologyBeijingBe

By simulating test and study in laboratory, the structure and performance offrothing generator were determined. The relative curves between the frothing volume and gas velocityof foaming net, supplying liquid volume and the content of foaming agent were obtainedrespectively. There were an optimum gas-velocity of foaming net, an optimum supplying liquid volumeand an optimum content of foaming agent under the condition of the given material quality and shapeof foaming net and spraying form. The spraying froth is of a great assistance in collectingrespirable dust.

关键词： frothing generator dedusting efficiency gas velocity frothing volume liquid volume.

KDD-based rolling schedule model for plate mill

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Journal of University of Science and Technology Beijing 2005年第3期12卷 281-285页

作者： ZhichunMu DangxianMa ShaoboWang ChangsongWang InformationEngineeringSchool UniversityofScienceandTechnologyBeijingBeijing100083China MechanicalEngineeringSchool UniversityofScienceandTechnologyBeijingBeijing100083China

A novel method for generating a rolling schedule is presented, which is fundamentally different from the existing ones. KDD (knowledge discovery in database) techniques are applied for discovering association rules between rolling parameters in a large database of rolling operation, and based on these rules, the schedule for the crucial last six finishing passes is generated. Operational evaluation shows that the schedule generated by the new method outperforms that generated by existing methods. It also shows how in this application the human's domain knowledge is applied to speed up the KDD process and to ensure the validity of the knowledge discovered.

关键词： KDD rolling schedule modeling plate mill association rules

Thermodynamic factor in diffusion in the non-stoichiometric compounds Ni_3Ga and Pt_3In

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Rare Metals 2002年第3期21卷 186-189页

作者： YUANWenxia QIAOZhiyu 等 AppliedScienceSchool UniversityofScienceandTechnologyBeijingBeijing100083China MetallurgySchool UniversityofScienceandTechnologyBeijingBeijing100083China

The thermodynamic factor in diffusion in the L1_2-type non-stoichiometricintermetallic compounds Ni_3Ga and Pt_3In was derived from the experimentally measured activities ofGa and In, respectively. The results show that the thermodynamic factor in diffusion in the Ni_3Gaand Pt_3In compounds exhibits the maximum near the stoichiometric composition with the variation ofcomposition over the compound region. The values indicate strong interaction between Ni and Gaatoms, as well as Pt and In atoms, respectively, as expected in ordered alloys.

关键词： thermodynamic factor diffusion Ni_3Ga Pt_3In