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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 {2. 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

Prediction of Rock Burst with Deep Mining Excavation in Linglong Gold Mine

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Journal of university of science and Technology {2. 2001年第4期8卷 241-243页

作者： Meifeng Cai, Jinan Wang, Shuanghong Wang Civil and Environmental Engineering school, university of {2. and Technology beijing, beijing 100083. china Univ Sci & Technol beijing Sch Civil & Environm Engn Beijing 100083 Peoples R China

To predict rock burst in deep mining excavation in Linglong gold mine, systematical laboratory tests of mechanical properties of rock, in situ stress measurement and 3-D FEM analysis on energy distribution in rock mass surrounding deep mining rooms were carried out. According to various prediction criteria of rock burst, it is concluded that rock burst is liable to occur during deep mining excavation in the mine.

关键词： rock burst prediction deep mining excavation Linglong gold mine

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 {2. 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

High Temperature Ductility Loss of 16MnCr5 Pinion Steels

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International Journal of Minerals,Metallurgy and materials 1998年第3期12卷 123-128页

作者： Haiwen Luo Pei Zhao Zijiu Dang(Metallurgy school, university of {2. and Technology beijing, beijing 100083. china) Metallurgy school University of Science and Technology Beijing Beijing 100083 China

A wide ductility trough covering from 700 to 1100 is observed in the curve of Reduction of Area (RA) *** for 16MnCr5 pinion steel. At 750℃, corresponding to the minimum of RA, it is grain boundary slidingthat controls its hot ductility rather than usual Deforming Induced Ferrite (DIF), which can only appear just below750℃ and slightly improve hot ductility. The volume fraction of ferrite is dependent on the strain and strain *** a critical strain must be necessary for formation of DIF then with strain rate increasing, the volume fractionof DIF decreases but RA is elevated. In the γ phase region, hot ductility is seriously deteriorated because of grainboundary sliding promoted by oxidcs and sulfides at the grain boundary and recovered because of dynamic recrystal-lization at higher temperature; when strain rate increases, ductility is improved as there is insufficient time for cracksto propagate along the γ grain boundary as well as dynamically precipitating, and ductility trough becomes narrowerbecause the temperature for onset of dynamic recrystallization decreases. In addition, γ→α phase transformationintroduced by temperature drop before the tensile test encourages precipitation of AlN and impairs ductility.

关键词： hot ductility deforming induced ferrite grain boundary sliding precipitates

Functionally Gradient material Made by IncrementalMelting and Solidification Process

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International Journal of Minerals,Metallurgy and materials 1999年第3期13卷 205-207页

作者： Chengchang Jia Hongbo Tian Tao Lin Zhimeng Guo Nobuyoshi Sasaki(material science and Engineering {2.. university of science and Technology beijing. beijing, 100083. china)(CADIC Cooperation. Kawasaki, 2.3. Japan) material science and Engineering {2. University of Science and Technology Beijing Beijing 100083 China CADIC Cooperation Kawasaki 213 Japan

A new technique IMS (Incremental Melting and Solidification Process) has been introduced. A kind of cast steel high Mn foundry alloy gradient rnalerial was produced by this process. The microstructure and mechanical properties of the alloy were tested. Fe and Mn in the samples were measured by EPMA. The experimental results show that the content and hardness of Fe-Mn alloy vary continuously and the IMS process is an alternative way in producing metal matrix gradient material. It is possible for these materials to be made into some parts such as camshaft.

关键词： IMS process FGM melting solidification

Synchronization of Digital Chaos in Secure Communication Systems

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Journal of university of science and Technology {2. 2001年第4期8卷 299-305页

作者： Geng Zhao, Deling Zheng, ShaojunHuang 1)College of Electric science and Technology beijing. beijing 100070, china 2.Information Engineering school, university of science and Technology beijing. beijing 100083. china Coll Elect Sci & Technol beijing Beijing 100070 Peoples R China Univ Sci & Technol beijing Informat Engn Sch Beijing 100083 Peoples R China

The theories of synchronization based on secure communications using digital chaos are presented. A new synchronous method-cycles-interval Pulse drive is developed and realized. Experimental results show it is available, and in order to reduce synchronous noise, a method using model references solves the ratio of signal power to noise power, so the secure communication system can be realized.

关键词： digital chaotic synchronization cycles-interval pulses drive synchronous noise model reference

The evolution and morphological stability of a spherical crystal

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science china(Technological sciences) 2008年第3期51卷 225-243页

作者： CHEN MingWen1,2. WANG ZiDong2.& XU JianJun3,4 1 school of Applied sciences, {2. of science and Technology beijing, beijing 100083. china 2.school of materials science and Engineering, {2. of science and Technology beijing, beijing 100083. china 3 school of Mathematical sciences, Nankai {2., Tianjin 300071, china 4 Department of Mathematics and Statistics, McGill {2., Montreal H3A 2.6, Canada 1. school of Applied sciences University of Science and Technology Beijing Beijing 100083 China 2. school of materials {2. and Engineering University of Science and Technology Beijing Beijing 100083 China 3. school of Mathematical sciences Nankai University Tianjin 300071 China 4. Department of Mathematics and Statistics McGill University Montreal H3A 2K6 Canada

The growth model of a spherical crystal in the undercooled melt including the surface energy, interfacial kinetics and convective flow is established. The effect of the convective flow induced by a small far field flow on the evolution and morphological stability of the interface of the spherical crystal is studied. The interface shape of the spherical crystal, which is affected by the far field flow, and the dispersion relation of the growth rate of amplitude of the perturbed interface are derived. It is shown that the convection induced by the far field flow makes the interface of the growing spherical crystal further grow in the upstream direction of the far field flow and inhibit growth in the downstream direction; the interface of the decaying spherical crystal further decays in the upstream direction and inhibits decay in the downstream direction. The theoretical result suggests that both the growth of the sphere in the upstream direction and the decay of the sphere in the downstream direction make the spherical crystal tend to evolve into an oval; the morphological stability of the interface depends on a certain radius R c such that the spherical crystal is unstable when its radius is greater than R c and stable when its radius is less than R c . The surface energy and interfacial kinetics have strong stabilizing effects on the growth of the spherical crystal. In the meantime interfacial kinetics is a table factor of the interface when the interface of the sphere is growing; it is an unstable factor of the interface when the interface is decaying.

关键词： solid-liquid interface spherical crystal convective flow crystal growth morphological stability

Multimedia Data Coding and its Development

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International Journal of Minerals,Metallurgy and materials 2000年第3期14卷 229-232页

作者： Xingye Yu, Yang Yang (Information Engineering school, university of {2. and Technology beijing, beijing 100083. china) Information Engineering school University of Science and Technology Beijing Beijing 100083 China

The requirements of data coding in multimedia applications are presented, the current technique of coding and relative standards is introduced, then the work that have been doing is presented, i.e. the wavelet-based coding method and the VE (Visual Entropy)-based coding method. The experiment results prove that these methods have gained a better perceptual quality of a reconstructed image and a lower bit rate. Their performance evaluations are better than JPEG (Joint Photographic Experts Group) coding. Finally, the future topics of study are put forward.

关键词： multimedia data coding MPEG (Moving Picture Experts Group) VE (Visual Entropy)

GTA Welds of Iron-Aluminide Based Alloys

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Journal of university of science and Technology {2. 2001年第1期8卷 39-42页

作者： Dechun Gao, Wangyue Yang, Min Dong, Jihua Huang, Yuanding Huang, Zuqing Sun material science and Engineering {2., university of science and Technology beijing, beijing 100083. china Univ Sci & Technol beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China

The weldability of two Fe3Al-based intermetallic alloys and one Fe-16%Al-based (atom fraction) alloy has been investigated for gas tungsten are (GTA) welding on sheets with a thickness of 2.mm. The results indicated that pre-heating and post-annealing treatment were important procedures for retarding cold crack initiation and the propel selection of filler could effectively improve the weldability. For the same alloys with the same welding filler, it is better to choose lower welding current, in another word, lower heat input.

关键词： iron-aluminide gas tungsten arc welding weldability filler