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Fractal image compression based on fuzzy theory

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Journal of university of science and Technology beijing 2002年第3期9卷 228-232页

作者： Berthe Kya and Yang YangInformation engineering school, university of {3. and Technology beijing, beijing 100083. china (Received 2001-11-13. Information engineering school University of Science and Technology Beijing Beijing 10083 China ***

Though progress has been made in fractal compression techniques, the longencoding times still remain the main drawback of this technique, which results from the need ofperforming a large number of range-domain matches. The total encoding time is the sum of the timerequired to perform each match. In order to make this method more efficient in practical use, thefuzzy theory based on feature extraction of the projection and normalized codebook method has beenprovided to optimize the encoding time, based on the c-means clustering approach. The results of theimplementation of Rate Mean Square (RMS), Peak signal noise ratio (PSNR) and the encoding time ofthis proposed method have been compared to other methods like the Feature Extraction andSelf-orgarnization methods to show its efficiency.

关键词： fractal compression fractal optimization fuzzy logic c-mean clusteringalgorithm hybrid fractal-fuzzy compression

Metal deformation in skew rolling step-shaft

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Journal of university of science and Technology beijing 2003年第5期10卷 59-63页

作者： Yongqiang Kang, Jinping Liu, Cuiping Yang, and Zhenghuan HuMechanical engineering school, university of {3. and Technology beijing, beijing 100083. china Mech. Eng. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

The process of rolling step-shaft was simulated with the help of the FEM(Finite-Element Model) software-DEFORM^(TM) 3.. The characteristics of metal flow in differentperiods were analyzed, and the curve of variety in non-round area at different cross-sections of therolled piece, the curve of variety in bulge volume and the curve of variety in non-column volumewere obtained. On this base the method of tool design is worked out and validated by experiment.

关键词： skew rolling FEM metal deformation non-column volume bulge volume

Interactive graphics mechanical optimum design

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International Journal of Minerals,Metallurgy and Materials 1997年第3期11卷 54-56页

作者： WANG Guobiao (Resources engineering school, university of {3. and Technology beijing, beijing 100083. china)

Virtually all conventional optimizations are Performed in a batch computer environment. No graphic information during the optimization process is provided. The research tactics and implementation procedure of interactivegraphics in mechanical optimum design are presented. An interactive Graphics Mechanical Optimum Design Program(IGMODP) for microcomputers is developed. The example of wheeled loader' s working device optimum design usingIGMODP is carried out.

关键词： interactive graphics mechanical optimum design computer program

Electrochemical Study of Hypophosphite

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International Journal of Minerals,Metallurgy and Materials 1998年第1期12卷 23-25页

作者： Yuguo Yang Dongbai Sun Dongbai Sun Dejun Yang (Materials science and engineering school, {3. of science and Technology beijing, beijing 100083. china) Materials science and engineering school University of Science and Technology Beijing Beijing 100083 China

Electrochemical behavior of hypophosphite was studied with cyclic voltammogram in acidic solution(pH = 4.6) at 80℃. Two anodic peaks were observed on gold electrode at - 0.44V and - 0.59 V (SCE),respectively, and no corresponding cathodic peaks were obtained. The one at - 0.44 V wits ascribed to the oxidation oftautomeric form of hypophosphite, the other at - 0.59 V was due to the oxidation of absorbed form of hypophosphite. The two oxidation reactions were believed to be the electron source of nickel ion reduction in electrolessnickel processes.

关键词： cyclic voltammogram electroless nickel plating gold electrode hypophosphite

In Situ Studies of Deformation and Fracture in Sputtering Copper Film

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International Journal of Minerals,Metallurgy and Materials 2000年第1期14卷 38-41页

作者： Jinxu Li Yimin Zeng Yanbin Wang Wuyang Chu Materials science and engineering school, {3. of science and Technology beijing, beijing 100083. china Materials science and engineering school University of Science and Technology Beijing Beijing 100083 China

Nanocrystalline copper films were prepared by sputtering and then in situ straining experiments were performed using a trans- mission electron microscope. Macroscopically, these copper films exhibited very low ductili... 详细信息

关键词： in situ straining, deformation fracture nanocrystalline copper film

Microstructure Characteristics and Apparent Viscosity of Hypereutectic Al-24%Si Alloy Melt During Semi-solid State Stirring

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Journal of university of science and Technology beijing 2001年第2期8卷 126-128页

作者： Yanjun Li, Weimin Mao, Zisheng Zhen, Xueyou Zhong (Material science and engineering school, {3. of science and Technology beijing, beijing 100083. china) Univ Sci & Technol beijing Mat Sci & Engn Sch Beijing 100083 Peoples R China

The microstructural evolution and apparent viscosity of hypereutectic Al-24%Si alloy during semi-solid state shearing were studied with a Searte type viscometer. When the alloy melt was continuously stirred from 720 degreesC to eutectic temperature, the primary Si crystals were gradually changed from elongated platelets to near-spherical shapes. It was found that some nondendritic a-phase formed when the melt was stirred below 585 degreesC. The experiment showed that the semi-solid stirring had strong effect on inhibiting the anisotropic growth of Si crystals during solidification. The apparent viscosity of the alloy melt increased slowly with the decreasing of temperature before the formation of nondendritic alpha -phase, which caused the dramatic increase of apparent viscosity.

关键词： hypereutectic Al-Si alloy solidification structures apparent viscosity

Nonlinear Aeroelastic Response of High-aspect-ratio Flexible Wings

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Chinese Journal of Aeronautics 2009年第4期22卷 355-363页

作者： zhang Jian,Xiang Jinwu school of Aeronautic science and {3.,beijing university of Aeronautics and Astronautics,beijing 100191,china [a]school of Aeronautic science and engineering Beijing University of Aeronautics and Astronautics Beijing 100191 China

The aeroelastic analysis of high-altitude, long-endurance （HALE） aircraft that features high-aspect-ratio flexible wings needs take into account structural geometrical nonlinearities and dynamic stall. For a generic nonlinear aeroelastic system, besides the stability boundary, the characteristics of the limit-cycle oscillation （LCO） should also be accurately predicted. In order to conduct nonlinear aeroelastic analysis of high-aspect-ratio flexible wings, a first-order, state-space model is developed by combining a geometrically exact, nonlinear anisotropic beam model with nonlinear ONERA （Edlin） dynamic stall model. The present investigations focus on the initiation and sustaining mechanism of the LCO and the effects of flight speed and drag on aeroelastic behaviors. Numerical results indicate that structural geometrical nonlinearities could lead to the LCO without stall occurring. As flight speed increases, dynamic stall becomes dominant and the LCO increasingly complicated. Drag could be negligible for LCO type, but should be considered to exactly predict the onset speed of flutter or LCO of high-aspect-ratio flexible wings.

关键词： nonlinear aeroelasticity limit-cycle oscillation Galerkin methods geometrical nonlinearities dynamic stall HALEaircraft

A new composite:spray-deposited M2 high speed steel reinforced by WC particles

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International Journal of Minerals,Metallurgy and Materials 1997年第3期11卷 14-17页

作者： zhang Liying TIAN Haige HUANG Thuo WU Chengyi (Material science and engineering {3., university of science and Technology beijing, beijing 100083. china) Univ of science and Technology Beijing Beijing China

The fabrication of the high speed steel matrix composites reinforced by WC particles utilizing the ultrasonicgas atomization and spray-deposition was studied. The change of microstware and mechanical Properties of thecomposites added WC Particles were investigated and analyzed as well. As some results, the WC particles exhibit tWomorphologies (spherical and angular) with different content of WC particles; and with the increase of content of WCparticles, the hardness of the composites increases, yet the bending strength appears a trend of decreasing.

关键词： spray-deposition high speed steel composite

Fuzzy Pattern Recognition in Atlas and Images of the Unevenness of Carbide in Tool Steel

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Journal of university of science and Technology beijing 2001年第3期8卷 234-236页

作者： Hui zhang, Angui Li, Zhigang zhang, Li Jiang Applied science {3., university of science and Technology beijing, beijing 100083. china Univ Sci & Technol beijing App Sci Sch Beijing 100083 Peoples R China

Fuzzy pattern recognition has been employed to identify some atlas and images of the unevenness of carbide in tool steel. Three models have been constructed. These models were based on fuzzy mathematics theory, as well as fuzzy pattern recognition method. Distribution rule of the unevenness of eutectic carbide in ledeburite steel is proposed in these models respectively.

关键词： fuzzy mathematics fuzzy and pattern recognition characteristic specimen