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Analysis method on shoot precision of weapon in small-sample case

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Journal of Systems Engineering and Electronics 2007年第4期18卷 781-784页

作者： Jiang Jun Song Baowei Liang Qingwei coll. of Marine Northwestern Polytechnical Univ. Xi'an 710072 P. R. China

Because of limits of cost, in general, the test data of weapons are shortness. It is always an important topic that to gain scientific results of weapon performance analyses in small-sample case. Based on the analysis of distribution function characteristics and grey mathematics, a weighting grey method in small-sample case is presented. According to the analysis of test data of a weapon, it is proved that the method is a good method to deal with data in the small-sample case and has a high value in the analysis of weapon performance.

关键词： weapon small-sample shoot precision statistical characters

Effect of Nb on the Interfacial Wettability in Al_2O_3/Medium Mn Steel

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Journal of Materials Science & Technology 2003年第6期19卷 625-627页

作者： Sirong YU, Yaohui LIU and Zhenming HEcoll.ge of Materials Science and Engineering, Jilin University, Changchun 130025, China coll. of Mat. Sci. and Eng. Jilin Univ. Changchun 130025 China

To develop medium Mn steel (MMS) matrix composites reinforced by AI2O3 particles, the effect of Nb on the interfacial wettability of AI2O3/MMS and its mechanism were investigated in this paper. The results show that the wetting angle of the specimens with different Nb contents are bigger than that of the specimen without Nb at the first stage, and then decreases with time at 1450℃. At certain time, the wetting angle is lower than that of the specimen without Nb. At 1550 and 1600℃, the wetting angle of the specimens containing Nb decreases quickly with time at first stage. After 10 min, the wetting angle reaches a steady state, and hardly changes with time. The mechanisms of Nb to improve the wettability can be attributed to the enrichment of Nb at the interface and Nb serves as surface active agent of MMS at T1550℃, and reduces the interfacial energies.

关键词： Madium Mn steel A12O3 Nb Wettalility

REAL-TIME FLOOD FORECASTING MODELING OF 1D UNSTEADY CHANNEL FLOW AND KALMAN FILTER

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Journal of Hydrodynamics 2001年第1期13卷 64-69页

作者： Li, Z.J. Weng, M.H. coll. of Water Res. and Environ. Hohai Univ. Nanjing 210024 China

The model of 1D unsteady channel flow combined with the Kalman filter for real-time channel flood forecasting was attempted. The suitable upstream and downstream boundary conditions were suggested. The system equation was given by the linearization of the finite difference equations of the mass conservation and momentum equations as well as the boundary conditions. In the Kalman filter updating model, because the number of measurement variable is less than that of state-space variables, the measurement error covariance matrix could be estimated in real time through the innovation sequence, and the system error covariance matrix needs to be estimated preliminarily. A real example of flood forecasting in the Huaihe River was given to explain how the method works. The results show that the model is reasonable and effective.

关键词： Channel flow Computer simulation Kalman filtering Unsteady flow

Characterization of ZnO Based Varistor Derived from Nano ZnO Powders and Ultrafine Dopants

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Journal of Materials Science & Technology 2005年第2期21卷 183-186页

作者： Weizhong YANG, Dali ZHOU, Guangfu YIN, Runsheng WANG and Yun ZHANG coll.ge of Material Science and Engineering, Sichuan University, Chengdu 610064, China coll. of Mat. Sci. and Eng. Sichuan Univ. Chengdu 610064 China

Nanosized ZnO powders were prepared with a two-step precipitation method. The average size of ZnO particles was about 80 nm and their size distribution was narrow. Combining with ultrafine additive powders, ZnO base varistor was produced via an oxide mixing route. ZnO varistor derived from normal reagent grade starting materials was investigated for comparison purpose. Outstanding microstructure of the ZnO varistor derived from nanosize ZnO powders and ultrafine dopants was obtained: uniform distribution of fine ZnO grains (less than 3 microns), grain boundary and the dopant position. Higher varistor voltage (U=492 V/mm) and nonlinear coefficient (α=56.2) as well as lower leakage current (TL=1.5 μuA) were achieved. The better electrical properties were attributed to the uniform microstructure, which in turn led to stable and uniform potential barriers. Also this improved technique is more feasible for producing ZnO nanopowders and resulting varistor in large scales.

关键词： Zinc oxide (ZnO) Varistor Nanopowders Ultrafine dopants Two-step precipitation

Robust H_∞ output feedback controller design for uncertain discrete-time switched systems via switched Lyapunov functions

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Journal of Systems Engineering and Electronics 2007年第3期18卷 584-590页

作者： Du Dongsheng Jiang Bin Dept. of mathematics and Physics Huaihai Inst. of Technology Lianyungang 222005 P. R. China coll. of Automation Engineering Nanjing Univ. of Aeronautics and Astronautics Nanjing 210016 P. R. China

The H∞ output feedback control problem for uncertain discrete-time switched systems is reasearclled. A new characterization of stability and H∞ performance for the switched system under arbitrary switching is obtained by using switched Lyapunov function. Then, based on the characterization, a linear matrix inequality （LMI） approach is developed to design a switched output feedback controller which guarantees the stability and H∞ performance of the closed-loop system. A numerical example is presented to demonstrate the application of the proposed method.

关键词： H∞ performance LMI output feedback robustly stable.

FLOW FIELD CHARACTERISTICS OF THE SAND FUNNEL AND ITS MECHANICS OF SEDIMENT TRANSPORT

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Journal of Hydrodynamics 2002年第3期14卷 130-134页

作者： Wang, Shun-Jiu Zhou, Zhu Hou, Jie Qiu, Xiu-Yun Ding, Jing Hou, Yu coll. of Hydraulic Eng. Sichuan Univ. Chengdu 610065 China coll. of Water Conservancy Xinjiang Agric. Univ. Wulumuqi 830052 China coll. of Hydropower Eng. Sichuan Univ. Chengdu 610065 China Dept. of Geogr. Zhongshan Univ. Guangzhou 510275 China

The flow in funnel chamber is typical three-dimensional flow. The experimental results of clear water flow field and muddy water flow field show that the flow characteristics in the funnel chamber are favorable to the separation of water and sand. Tangential velocity sustains the vortex strength of the funnel chamber, axial velocity is benefit to the sediment sinking, and radial velocity is benefit to sediment moving to desilting hole. So the sand funnel is successful in sediment disposal. The sand funnel projection has also good desilting effectiveness in practice. Its average flushing discharge is 3% of inlet canal discharge, the sand disposal rate is 100% for the sand with grain diameter of more than 0.5 mm, and is more than 90% for the sand with grain diameter of less than 0.5 mm.

关键词： Mechanics Sand Sediments Three dimensional Vortex flow Water

Application of Genetic Programming in Predicting Infinite Dilution Activity Coefficients of Organic Compounds in Water

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Chinese Chemical Letters 2003年第9期14卷 987-990页

作者： Yi Lin CAO, Huan Ying LI coll.ge of Chemistry and Environmental Science, Henan Normal University, Xinxiang 453002 coll. of Chem./Environmental Science Henan Normal University Xinxiang 453002 China

In this paper, we calculated 37 structural descriptors of 174 organic compounds. The 154 molecules were used to derive quantitative structure - infinite dilution activity confficient relationship by genetic programming, the other 20 compounds were used to test the model. The result showed that molecular partition property and three-dimensional structural descriptors have significant influence on the infinite dilution activity coefficients.

关键词： Infinite dilution activity coefficients genetic programming.

Learning Bayesian networks using genetic algorithm

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Journal of Systems Engineering and Electronics 2007年第1期18卷 142-147页

作者： Chen Fei Wang Xiufeng Rao Yimei coll. of Information Technical Science Nankal Univ. Tianjin 300071 P. R. China

A new method to evaluate the fitness of the Bayesian networks according to the observed data is provided. The main advantage of this criterion is that it is suitable for both the complete and incomplete cases while the others not. Moreover it facilitates the computation greatly. In order to reduce the search space, the notation of equivalent class proposed by David Chickering is adopted. Instead of using the method directly, the novel criterion, variable ordering, and equivalent class are combined,moreover the proposed mthod avoids some problems caused by the previous one. Later, the genetic algorithm which allows global convergence, lack in the most of the methods searching for Bayesian network is applied to search for a good model in thisspace. To speed up the convergence, the genetic algorithm is combined with the greedy algorithm. Finally, the simulation shows the validity of the proposed approach.

关键词： Bayesian networks Genetic algorithm Structure learning Equivalent class

New Developed Welding Electrode for Improving the Fatigue Strength of Welded Joints

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Journal of Materials Science & Technology 2002年第6期18卷 527-531页

作者： Wenxian WANG, Lixing HUO, Yufeng ZHANG, Dongpo WANG and Hongyang JINGcoll.ge of Material Science and Engineering, Tianjin University, Tianjin 300072, China coll. of Mat. Sci. and Eng. Tianjin Univ. Tianjin 300072 China

A new welding electrode, low transformation temperature electrode (LTTE), was introduced in this paper. It was described in design principle, mechanics, chemical compositions of their deposited metal and manufacturing methods. It was proved that the best transformation starting temperature from austenite to martensite of the deposited metal of LTTE was at about 191℃ and it was obtained by adding alloying elements such as Cr, Ni, Mn and Mo. The microstructure of the weld metal of the LTTE was low carbon martensite and residual austenite. The compressive residual stress was induced around the weld of the LTTE and the -145 MPa in compression could be obtained in middle of weld metal. The fatigue tests showed that the fatigue strength of the longitudinal welded joints welded with the LTTE at 2×106 cycles was improved by 59% compared with that of the same type of welded joints welded with conventional E5015 and the fatigue life was increased by 47 times at 162 MPa. It is a very valuable method to improve the fatigue performance of welded joints.

关键词： Low transformation temperature electrode Compressive residual stress Fatigue strength Welded joints