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Progress in Natural Science:Materials International 2007年第9期17卷 1095-1103页

作者： Zhong Lusheng(National Laboratory of industrial Control technology,institute of industrial Process Control,Zhejiang University,Hangzhou 310027,China) National Laboratory of industrial Control technology Institute of Industrial Process Control Zhejiang University Hangzhou 310027 China

This paper addresses the problems of parameter estimation of multivariable stationary stochastic systems on the basis of observed output *** main contribution is to employ the expectation-maximisation(EM)method as a means for computation of the maximum-likelihood(ML)parameter estimation of the *** form of the expectation of the studied system subjected to Gaussian distribution noise is derived and parameter choice that maximizes the expectation is also *** results in an iterative algorithm for parameter estimation and the robust algorithm implementation based on technique of QR-factorization and Cholesky factorization is also ***,algorithmic properties such as non-decreasing likelihood value,necessary and sufficient conditions for the algorithm to arrive at a local stationary parameter,the convergence rate and the factors affecting the convergence rate are *** study shows that the proposed algorithm has attractive properties such as numerical stability,and avoidance of difficult initial conditions.

关键词： parameter estimation system identification maximum likelihood(ML) stochastic state-space system EM algorithm

Hybrid Genetic Algorithms with Fuzzy Logic Controller

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Journal of Systems Engineering and Electronics 2001年第3期12卷 9-15页

作者： Zheng Dawei & Gen Mitsuo Department of industrial and Systems Engineering, Ashikaga institute of technology, 326, Japan Department of industrial and Systems Engineering Ashikaga Institute of Technology 326 Japan

In this paper, a new implementation of genetic algorithms (GAs) is developed for the machine scheduling problem, which is abundant among the modern manufacturing systems. The performance measure of early and tardy completion of jobs is very natural as one's aim, which is usually to minimize simultaneously both earliness and tardiness of all jobs. As the problem is NP-hard and no effective algorithms exist, we propose a hybrid genetic algorithms approach to deal with it. We adjust the crossover and mutation probabilities by fuzzy logic controller whereas the hybrid genetic algorithm does not require preliminary experiments to determine probabilities for genetic operators. The experimental results show the effectiveness of the GAs method proposed in the paper.

关键词： Machine scheduling problem Hybrid genetic algorithms Fuzzy logic.

R & D ACTIVITIES ON AEROSPACE MATERIALS IN korea

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Acta Metallurgica Sinica(English Letters) 1996年第6期9卷 417-421页

作者： H.M. Kim(korea institute of Machinery and Materials,korea ) korea Inst of Machinery and Materials South Korea

This paper briefly reviews research and development programs in korean aerospace industry,with an emphasis on aircraft materials technology. International collaborations in these areas are outlined and the R & D activities are highlighted against the background of the national *** is shown that the investment from government agencies and large enterprises has led to healthy development of aerospace materials industries in korea.

关键词： R & D aerospace materials international collaboration korea

Effect of Current Density on Al Alloy Microplasma Oxidation

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Journal of Materials Science & technology 2001年第6期17卷 657-660页

作者： Shigang XIN, Zhaohua JIANC, Fuping WANG, Xiaohong WU and Liancheng ZHAO Harbin institute of technology, Harbin 150001, China Tadao SHIMIZU Department of industrial Chemistry. Chiba institute of technology, Japan [Manus Harbin Inst Technol Harbin 150001 Peoples R China Chiba Inst Technol Dept Ind Chem Chiba Japan

The microplasma oxidation process of LY 12 Al alloy in Na2SiO3-KOH-NaAL2 system has been studied. The voltage-time curve of oxidation process is changed with the variation of current ... 详细信息

The microplasma oxidation process of LY 12 Al alloy in Na2SiO3-KOH-NaAL2 system has been studied. The voltage-time curve of oxidation process is changed with the variation of current densities. The voltage breakdown and hardness of coating increase with increasing current density. The phase composition, morphologies, element and the distribution of ceramic coating are investigated by XRD, EPMA.

关键词： Al Cu Effect of Current Density on Al Alloy Microplasma Oxidation

Superplasticity in an Aluminum Alloy 6061/Al_2O_3p Composite

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Journal of Materials Science & technology 2001年第6期17卷 653-656页

作者： Lihong HAN, Jitai NIU and Darning JIANG The National Key Laboratory of Advanced Welding Production technology, Harbin institute of technology, Harbin 150001, China Tsunernichi Imai National industrial Research Harbin Inst Technol Natl Key Lab Adv Welding Prod Technol Harbin 150001 Peoples R China Natl Ind Res Inst Nagoya Kita Ku Nagoya Aichi 462 Japan

The superplasticity of an Al203p/6061Al composite, fabricated by powder metallurgy techniques, has been investigated. Instead of any special thermomechanical processing or hot rolling, simple hot extrusion has been employed to obtain a fine grained structure before superplastic testing. Superplastic tensile tests were performed at strain rates ranging from 10-2 to 10-4 s-1 and at temperatures from 833 to 893 K. A maximum elongation of 200% was achieved at a temperature of 853 K and an initial strain rate of 1.67×103 s-1. The highest value obtained for the strain rate sensitivity index (in) was 0.32. Differential scanning calorimeter was used to ascertain the possibility of any partial melting in the vicinity of optimum superplastic temperature. These results suggested that no liquid phase existed where maximum elongation was achieved and deformation took place entirely in the solid state.

关键词： Al Superplasticity in an Aluminum Alloy 6061/Al2O3p Composite rate high DSC Figure

Microstructure of a Mo-Si-C-N multi-layered anti-oxidation coating on carbon/carbon composites by fused slurry

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Rare Metals 2009年第5期28卷 460-464页

作者： LAI Zhonghong MENG Songhe ZHU Jingchuan JEON Jaeho School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China Research Center for Composite Materials Harbin Institute of Technology Harbin 150001 China Department of Materials technology Korea Institute of Machinery ＆ Materials Changwon 641-010 Korea

A Mo-Si-C-N multi-layered anti-oxidation coating was in-situ fabricated by introducing nitrogen atmosphere during the fused sintering of Mo-Si slurry pre-layer on carbon/carbon composites. The phase composition and microstructure of the Mo-Si-C-N coating were characterized by X-ray diffractometry, optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The Mo-Si-C-N coating exhibited a three-layered structure. Besides the MoSi2/Si main-layer and the SiC bonding-layer, a surface layer of about 10 μm in thickness was synthesized on the coating surface. The surface layer mainly consisted of SiC nanowires and contained some Si3N4 and Si phases. SiC nanowires of 10 to 200 nm in diameter presented a terrace and distortion structure. Transmission electron microscopy indicated that the SiC nanowires grew along the preferred 〈111〉 direction. During oxidation test, SiC nanowires transmuted into SiO2 glass, which can play an important role in improving the oxidation resistance of C/C composites.

关键词： C/C composites coating microstructures anti-oxidation

EXPERIMENTAL STUDY OF FLOW STRUCTURE BEHIND A CIRCULAR CYLINDER WITH WAVY SURFACE BY PIV

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Journal of Hydrodynamics 2006年第1期18卷 97-103页

作者： ZHANG Wei Daichin Department of Mechanical Engineering Pohang University of Science and Technology Pohang 790-784 Korea Shanghai institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China

The wake behind a circular cylinder with wavy surface was investigated using single-frame PIV technique at Re=5200. The mean flow field and spatial distribution of turbulence statistics in the nodal, saddle and middle planes were presentcd and compared with those of a smooth cylinder. The near wake behind the wavy cylinder shows pronounced spanwise periodicity of flow structures. Compated with a smooth cylinder, the vortex formation region considerably expands in the streamwise direction, particularly reaching maxi mum in the saddle plane of the wavy cylinder. However, the longitudinal vortices in the nodal plane were noticeably suppressed in the transverse direction. In addition, the wake in the nodal plane contains the peak value of turbulent kinetic en ergy and the Reynolds shearing stress due to the intensive entrainment of free flow and the momentum exchange in the spanwise direction.

关键词： wavy cylinder wake structure PIV

Investigation of Nickel Oxide Used for Alloying in BOF Steelmaking

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International Journal of Minerals,Metallurgy and Materials 1997年第1期11卷 8-12页

作者： CHEN Weiqing ZHOU Rongzhang HUH Wanwook RHEE Changhee(Faculty of Metallurgy, USTB, Beijing, 100083, China)(Research institute of industrial Science and technology, Pohang, korea)

Direct alloying of nickel oxide in a hot simulator of LD converter was investigated in *** rate of nickel oxide in steelmaking process was analyzed with the test results. Under the condition oflower slag viscosity, the reduction rate of NiO increases and the [Ni] yield rises. When the slag viscosity is higher, a lot of metal particles with higher Ni content are contained in the slag so as to decrease the [Ni] yield.

关键词： nickel oxide,direct alloying BOF steelmaking

Secondary Synthesis of Ti-containing Zeolite

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石油学报（石油加工） 1997年第S1期13卷 84-91页

作者： Wang Xiangsheng and Guo Xinwen (institute of industrial Catalysts,Dalian University of technology, Dalian 116012)

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关键词： Secondary synthesis Ti containing zeolite oxidation phenol styrene hydroxy nests.