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Numerical Simulation on Irregular Shrinkage of Initial Shell in Continuous Casting of Steel

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International Journal of Minerals,metallurgy and Materials 1999年第2期13卷 103-106页

作者： Dejun jing Kaike Cai(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 microstructures of steel, a thermo-elasto-plastic stress model of continuously casting billets is established to study hailal solidifying process in molds. Results show that peritectic phase transformation contributes greatly to the irregular shrinkage ofinitial shell, which makes the billets vulnerable to surface defects.

关键词： thermo-elasto-plastic stress model peritectic phase transformation irregular shrinkage of initial shell

Design and Synthesis of Ti-ZrO_2 Functionally Graded Materials

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Journal of university of science and technology beijing 2001年第1期8卷 48-52页

作者： lidong Teng, Fuming Wang, Wenchao li metallurgy school, university of science and technology beijing, beijing 100083, china Univ Sci & Technol beijing Met Sch Beijing 100083 Peoples R China

Functionally graded materials (FGMs) based on titanium-zirconia system have been prepared by powder metallurgical method. The graded interlayer number and the compositional distribution have been designed by elastic finite element method. The interfacial microstructure between layers, the combining state of phases between Ti and ZrO2 have been investigated by means of XRD (X-ray diffraction), SEM (scanning electron microscope), EDS (energy dispersive spectrometer) and so on. The co-existing region of Ti and ZrO2 has been determined by thermodynamic calculation to control the sintering atmosphere. The experimental results show that the joint between Ti and ZrO2 phases is physical in this composite and ZrO2 mainly exists as tetragonal phase. The microstructure of Ti-ZrO2 system FGM exhibits a transition from a zirconia particle dispersion in a titanium matrix to an inverse dispersion of titanium in zirconia. The gradient structure of titanium and zirconia can relieve thermal stress.

关键词： Ti-ZrO2 system functionally graded material thermodynamic analysis finite element method

Oxidation of O'-SiAlON-ZrO_2 Composite Ceramics

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Journal of university of science and technology beijing 2001年第1期8卷 43-47页

作者： Xidong Wang , Hong Bao, Wenchao li metallurgy school, university of science and technology beijing, beijing 100083, china Department of metallurgy, East china university of metallurgy Maan Shan 243002, china Univ Sci & Technol beijing Met Sch Beijing 100083 Peoples R China E china Univ Met Dept Met Maan Shan 243002 Peoples R China

The oxidation kinetics of O'-SiAlON-ZrO2 composite ceramics in the temperature range of 1373-1773K has been studied. The oxidation experiments with powder and plates of O'-SiAlON-ZrO2 composite ceramics in air have been carried out. The overall activation energy of oxidation reaction is 263.69 kJ/mol. The products and structures of O'-SiAlON-ZrO2 oxidation layer have been analysed by XRD (X-ray diffraction), SEM (scanning electron microscope) and AFM (atomic force microscope).

关键词： O '-SiAlON ZrO2 ceramics oxidation

Equilibrium Precipitation of Niobium Carbonitride in Austenite

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International Journal of Minerals,metallurgy and Materials 1998年第3期12卷 119-122页

作者： Fuming Wang Wenchao li(Applied science school, university of science and technology beijing, beijing 100083, china) Applied science school University of Science and Technology Beijing Beijing 100083 China

The equilibrium between niobium carbonitride and austenite has been studied. Experimentally, X-raydiffaction technique was adopted to verify that the precipitates have the same composition and structure. Theoretical-ly, Hillert and Staffansson's regular model about stoichimetric phase was used to describe the thermodynamic proper-ties of multi-component precipitate. Calculated results agree well with experimental values from literatures.

关键词： equilibrium niobium precipitate, austenite

Annealing Texture Evolution of Ti-IF Steel during Batch Annealing

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International Journal of Minerals,metallurgy and Materials 1998年第3期12卷 175-179页

作者： jing Shi Xianjin Wang(Material science and Engineering school, university of science and technology beijing, beijing 100083, china) Material science and Engineering school University of Science and Technology Beijing Beijing 100083 China

Texture development and recrystallization behavior of Ti-IF steel during Batch Annealing (BA) were investigared with X-ray diffraction and EBSP in lab, and the results were compared with research work on continu ous annealing (CA) with rapid heating rate. The basic tendencies are similar that eary nucleation takes place in ND fibers, RD fibers are consumed at the end of recrystallization, and ND texture dominates over annealing texture. However, the detailed texture transformation during batch annealing is different and somewhat more compicated than tha in rapid-heating process. Moreover, misorientation plays an important role in texture transformation of BA In addition, the results of EBSP are consistent with that of ODF well.

关键词： Ti-IF steel texture batch annealing X-ray diffraction EBSP

Application of Diagonal Recurrent Neural Network toDC Motor Speed Control Systems

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International Journal of Minerals,metallurgy and Materials 2000年第1期14卷 68-71页

作者： jing Wang Hui Chen Information Engineering school, university of science and technology beijing, beijing 100083, china Information Engineering school University of Science and Technology Beijing Beijine 100083 China

A new kind of dynamic neural network--diagonal recurrent neural network (DRNN) and its learning method and architecture are presented. A direct adaptive control scheme is also developed that is applied to a DC (Direct Current) speed control system with the ability to auto-tune PI (Proportion Integral) parameters based on combining DRNN with PI controller. The simulation results of DRNN show better control performances and potential practical use in comparison with PI controller.

关键词： diagonal recurrent neural network PI controller DC Motor speed control system

A WT-STFT combining Algorithm

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International Journal of Minerals,metallurgy and Materials 2000年第4期14卷 315-317页

作者： Xisheng li, Shaochun Wang (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 fast wavelet packet (WP) algorithm is presented, in which the wavelet transform (WT) and the short-time Fourier transform (STFT) are combined. As WT produces multiresolution of frequency and time, and STFT has a fas... 详细信息

关键词： signal processing, wavelet transform short-time Fourier transform Informatid

Numerical Simulation of Shrinkage Cavity Formation in Spheroidal Graphite Iron Castings Based on Micro Modeling

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International Journal of Minerals,metallurgy and Materials 1998年第1期12卷 9-12页

作者： Wenzhen li Baicheng liu Shantong Jin (metallurgy Engineering school, university of science and technology beijing, beijing 100083, china)(Department of Mechanical Engineering, Tsinghua university, beijing 100084, china) metallurgy Engineering school University of Science and Technology Beijing Beijing 100083 China Department of Mechanical Engineering Tsinghua University Beijing 100084 China

A micro-modeling method (MM) for the quantitative prediction of the shrinkage cavity formation in SGiron castings is proposed. The mathematical models describing the volume changes during the solidification ofspheroidal graphite cast iron are established based on the models of solidification kinetics. The shrinkage cavityformation of T-shaped SG iron castings is calculated with MM method. The calculated results are compared with theexperimental results. It is shown that the predicted size, shape and distribution of shrinkage cavity by MM methodare in good agreement with the measured results.

关键词： solidification shrinkage numerical simulation micro modeling spheroidal graphite cast iron

Improvement of Boxcar Integrator and Its Application to Low Resistance Measurement of Inductive Load Coil

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International Journal of Minerals,metallurgy and Materials 1998年第3期12卷 180-184页

作者： Xisheng li Shaochun Wang(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 boxcar integrator is described which is suitable for the low-repetition-rate signal processing. This boxcar integrator, named fixed-interval mode boxcar integrator, is able to reject harmonics other than the first harmonic component. It can also decrease the effective time constant In many situations, the antialiasing filter with narrow bandwidth will cause distortion of the input signal. The fixed-interval mode boxcar integrator with suitable gate width can achieve relative high performance without signal distortion because the bandwidth of its antialiasing filter can be wider than that in the fixed-Point boxcar integrator. ms boxcar integrator is used as majn part of signalprocessing circult in the low resisance measurement of inductive load coil. The results of experiments show that the fixed-interval boxcar integrator is suitable for low-repetition-rate use.

关键词： signal processing resistance measurement boxcar integrator