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Optimization of Fractal Iterated Function System(IFS) with Probability and Fractal Image Generation

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Journal of university of science and technology beijing 2001年第2期8卷 152-156页

作者： Berthe Kya, Yang Yang (Information Engineering school, university of science and technology beijing,{2.) Information Engineering school University of Science and Technology Beijing 100083 China

There are several methods for rendering fractal images based on IFS (Iterated Function System) in computer graphic; but one concern of the computer graphic community has been the efficiency rendering algorithms. The invariant measures arising from IFSP (Iterate Function System with Probability) using the probabilistic algorithm are also known as chaos games. The role of these probabilities to generate the image of the attractor has been investigated using a multi-fractal analysis. The conventional choice of probability associated with each set /S/ to generate the attractor in least time possible is introduced, then a new method based on the self similarity and multi-fractal analysis is presented. The efficiency of the new method has been proved over the conventional method.

关键词： optimization of fractal IFS compression IFSP multi-fractal analysis

Corrosion Fatigue Behavior of Duplex Stainless Steel in 3.5% Sodium Chloride Solution

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Journal of university of science and technology beijing 2001年第2期8卷 133-136页

作者： S. H Abubakir, Yinshun Wu, Baofeng Ding, Jiuqing Li Bei Cao (material science and Engineering {2., university of science and technology beijing, beijing 100083. china) material Sci. and Engineering school University of Science and Technology Beijing 100083 China

The corrosion fatigue behavior of duplex stainless steel (DSS) was studied at different cyclic stress levels in 3.5%NaCl (mass fraction, so as the follows) solution (pH=7) at 50 degreesC. The results showed that DSS was susceptible to pitting corrosion and corrosion fatigue. Both intergranluar corrosion cracking and transgranlular corrosion cracking initiated at the bottom of pitting holes. Furthermore, the corrosion fatigue properties of DSS in 3.5%NaCl solution may be relatived to complex electrochemical and mechanical coupling effects between the three phases (austenite, ferrite and martensite), where martensite and ferrite were anodic in the corrosion cell and could be prone to cracking under certain condition.

关键词： corrosion fatigue duplex stainless steel sodium chloride solution

Analytical criteria for local activity of CNN with five state variables and application to Hyper-chaos synchronization Chua's circuit

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Journal of university of science and technology beijing 2002年第4期9卷 311-318页

作者： Lequan Min and Xisong DongApplied science school,{2., beijing 100083. china Univ Sci & Technol beijing Appl Sci Sch Beijing 100083 Peoples R China

The analytic criteria for the local activity theory in one-port cellularneural network (CNN) with five local state variables are presented. The application to a Hyper-chaossynchronization Chua's circuit (HCSCC) CNN with 112. variables is studied. The bifurcation diagramsof the HCSCC CNN show that they are slightly different from the smoothed CNN with one or two portsand four state variables calculated earlier. The evolution of the patterns of the state variables ofthe HCSCC CNN is stimulated. Oscillatory patterns, chaotic patterns, convergent or divergentpatterns may emerge if the selected cell parameters are located in the locally active domains butnearby or in the edge of chaos domain.

关键词： cellular neural network local activity Hyper-Chaos Synchronization Chua's circuit five state variables chaos

Fabrication of pure copper rods containing continuous columnar crystals by continuous unidirectional solidification technology

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Journal of university of science and technology beijing 2004年第3期11卷 240-244页

作者： Hong zhang Jianxin Xie Zidong Wang materials science and Engineering {2., university of science and technology beijing, beijing 100083. china Mat. Sci. and Eng. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

Pure copper rods containing continuous columnar crystals were fabricatedusing the downward CUS (Continuous Unidirectional Solidification) equipment. When the technologicalparameters were set as the ranges of mould temperature 1100-1300℃, cooling distance (the distancefrom the exit of the cast mould to the start point of cooling) 10-2. mm, casting speed 0.2.2.5 mm/s,cooling water (2.-2.℃) volume 1000-132. L/h, and when these parameters matched reasonably, the CUSprocess was performed stably, and pure copper rods containing continuous columnar crystals withbright and smooth surface were produced. The dendritic arm spacing of the crystals in copper rodsdecreased with increasing the casting speed. The results of the texture by X-ray diffractionanalysis showed that the rods has strong fiber texture.

关键词： copper continuous unidirectional solidification mould temperature castingspeed microstructure texture

Effect of Preparation Condition on Low-density PS Particle Size and Distribution

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Journal of university of science and technology beijing 2001年第4期8卷 274-276页

作者： Huili Fan, Jiemin Liu, Meijuan Wen, Weixue Tian Applied science school.{2..beijing 100083. china Applied science school University of Science and Technology Beijing Beijing 100083 China

The preparation conditions were studied in order to obtain smaller, narrow size-distributed and low-density polystyrene (PS) micro-particles by suspension polymerization. The results show that some of preparation conditions, the shape and position of stirrers, and stirring rate etc., have important influence on the size and distribution of particles. The preparation conditions must be carefully designed and controlled in order to obtain high-quality PS beads. A bow-shaped stirrer is helpful to produce small-sized particles and narrow size distribution, and the upper edge of a stirrer should be set to the same level as the surface of mixture, and the stirring rate should be controlled in the range of 52.-600 r/min.

关键词： low-density micro-particles suspension polymerization preparation conditions

Irradiation Damage of Oxide Dispersion Strengthened Ferritic Steel after Recrystallization

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International Journal of Minerals,Metallurgy and materials 1998年第3期12卷 160-164页

作者： Benfu Hu Shunmi Peng H Takahashi(material science and Engineering {2., university of science and technology beijing, beijing 100083. china)(Faculty of Engineering, Hokkado university, Sapporo 060, Japan) material science and Engineering {2. University of Science and Technology Beijing Beijing 100083 China Faculty of Engineering Hokkado University Sapporo 060 Japan

The evolution of secondary defects and the characteristics of the void swelling of electrons irradiated Oxide Dispersion Strengthened Ferritic Steels (ODS steels) after recrystallization were studied. It was found that recrystallization increases the void swelling of ODS steel as compared with solution and injected He+ + D+ *** are two size ranges of voids formed in recrystallized ODS steel during irradiation, and bubbles can be preferential sites for the void formation. Polycrystal with low density of defects is formed, and sites where point defects disappear by irradiation decrease. This is the main reason for the increase of void swelling of ODS steel after recrystallization.

关键词： ODS steel recrystallization, electron irradiation

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,{2. 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

GTA Welds of Iron-Aluminide Based Alloys

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Journal of university of science and technology beijing 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 material Sci. and Engineering school Univ. of Sci. and Technology Beijing Beijing 100083 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

Effects of Na/K ratio on the phase structure and electrical properties of Na_xK_(1-x)NbO_3 lead-free piezoelectric ceramics

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Rare Metals 2010年第2期29卷 220-225页

作者： ZHANG Qian, ZHANG Boping, Li Haitao, and SHANG Pengpeng school of materials {2. and Engineering, university of science and technology beijing, beijing 100083. china school of materials {2. and Engineering University of Science and Technology Beijing Beijing China

Lead-free piezoelectric NaxK1-xNbO3（x = 0.3-0.8）（NKN） ceramics were fabricated by normal sintering at 1060°C for 2.*** and electrical properties of the ceramics were investigated with a special emphasis on the influence of Na *** grain size of the produced dense ceramic was decreased by increasing Na content.A discontinuous change in the space distance was found at the composition close to Na0.7K0.3NbO3 ceramic, which indicates the presence of a transitional composition between two different orthorhombic phases, which is similar to the behavior of morphotropic phase boundary（MPB） in NaxK1-xNbO3 *** MPB-like behavior contributes to the enhanced piezoelectric coefficient d33 of 12. pC/N, planar-mode electromechanical coupling coefficient kP of 2..6%, and dielectric constant εr of 703, respectively for the Na0.7K0.3NbO3 *** temperature TC and the transitional temperature TO-T from orthorhombic to tetragonal phase are observed at around 42.°C and 2.0°C, respectively.

关键词： lead-free piezoelectric ceramics NKN sintering morphotropic phase boundary(MPB)