Table of Content

31 January 2009, Volume 30 Issue 1

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Paper

Dynamic Finite Element Simulation of the Aluminum Alloy Hull at Landing

DU Zhi-qi, SHAO Peng-Li

2009, 30(1):  1-4.  doi:10.3969/j.issn.1000-1093.2009.01.001

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It is the most important R&D criteria for airborne armored vehicle to optimize the hull structure assured of both strength and weight control. The structure analysis simulation depends on the data of vehicle airborne test. The finite element model for the aluminum alloy body and its welded joint was built. The landing process of the vehicle was simulated by dynamic nonlinear finite element method. The transient results of displacement, strain and stress under normal, worse and worst air?drop conditions were obtained. The simulation results are in agreement with the actual experimental data, indicating that the finite element model and the simulation method are correct. The improved design for the body structure is provided.

Numerical Simulation of Supersonic Axisymmetric Inlet Flow Field

XIONG Zhi-ping, WU Xiao-song, XIA Qiang

2009, 30(1):  5-8.  doi:10.3969/j.issn.1000-1093.2009.01.002

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The complex flow fields of a supersonic ramjet inlet were numerically simulated by 2D ax- isymmetric compressible N-S equation solved with infinite volume method and second order upwind scheme, to obtain clear flow structure. Ine results show that, with the increase of inflow Mach num?ber, the total pressure recovery coefncient reduces, stable operating range increases, flow coefficient increases gradually and keeps being- nonvariant when the cone shock attaches the cowl lip; at the super?critical operation condition of the same inflow Mach number, with the increase of backpressure at the exit of the inlet terminal normal shock wave moves towards the throat, consequently, the loss of ter?minal shock wave weakens, the total pressure recovery coefficient at the exit of the inlet increases, the Mach number and the distortion degree in flow field at the exit of the inlet reduces respectively.

Design and Analysis of PN Code Fuze with High Precision in Low SNR Condition

WANG Li-jun, ZHAO Hui-chang, YANG Xiao-niu

2009, 30(1):  9-13.  doi:10.3969/j.issn.1000-1093.2009.01.003

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The design principle of pseudonoise (PN) code fuze was analyzed, and then its design prin?ciple based on tracking loop was proposed. The performance of code tracking loop was deduced and an?alyzed .The system performance was analyzed in detail. The simulated and analysed results show that this scheme has the high precision of distance determination (the error of distance determination （1σ)<0.1 m)，which can effectively work in low signal to noise ratio (SNR) condition, that is, it is difficult to be detected. This scheme can be easily implemented by digital technique using software method, wmch can enhance the flexibility and repeatability of the system design.

Resolution Ability of Fractional Fourier Transform in Multi- component Chirp Signal Center Frequency

LIU Feng, HUANG Yu, TAO Ran,WANG Yue

2009, 30(1):  14-18.  doi:10.3969/j.issn.1000-1093.2009.01.004

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The resolution ability of fractional Fourier transform (FRFT) in the center frequency was studied, when multi-component Chifp signal had only one Chirp-rate. From the estimation sector of the center frequency in the FRFl s numerical calculation, the center frequency’s resolution ability ex?pression was deduced. Based on partial differential equation, the influence of the sampling time, sam?pling frequency and Chirp-rate upon the resolution ability were analyzed further. The computer simula?tion results indicate that the smallest resolution ability of center frequency has the cave parabola rela?tionship about with Cnirp-rate and is greater than 2 MHz, when the sampling frequency is 400 MHz, sampling time is 2 μs and the value of Chirp-rate is no more than 100 MHz/ /μs .

Computation Model and Experimental Analysis for Effective Absorption Coefficient of the Multi-pore Materials

LU Yan-li, ZHANG Shuan-qin, XIE Wei,LV Xu-Iiang

2009, 30(1):  19-23.  doi:10.3969/j.issn.1000-1093.2009.01.005

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The physical mathematical model for the transmitting properties of laser in multi-pore sam?ples was established based on the wave optics theory. The varied relations of the effective absorption coefiicient εo( λ ) with the built-in absorption coefficient ε( λ ) of materials and the multi-pore con?struction parameters A/St were optimized. The maceration and high temperature sintering methods were used to fabricate the multi-pore construction with the material ε (1.06 μm) equaling to 0.56. The absorption coefficient around 1.06 μm was measured by Lambda 900 UV/VIS/NIR spectrome?ter. Experimental results show that the effective absorption coefficient eo(1.06 fxm) declines with in-creasing the multi-pore construction parameter A/ St,which is consistent with the theoretical compu?tation. Therefore, the multi-pore structure materials with better absorption performance can be pre?pared by adjusting the characteristic parameter A/St at a certain material absorption coefficient.

Influence of Interface Reflection on Positioning Performance and Restraining Technology

FU Jin, LIANG Guolong, ZHANG Guang-pu

2009, 30(1):  24-29.  doi:10.3969/j.issn.1000-1093.2009.01.006

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Based on the positioning solving principle of synchronous underwater acoustic positioning system, the effect of error in time-delay estimation from a single sensor on positioning precision was analyzed. Based on the characters of underwater acoustic channel, the change law in the phase differ?ence between direct sound and surface reflected sound was revealed when the target is in different loca?tion ;the physical mechanism of interfacial reflection influence on positioning precision was inquired in?to ;the signal processing logic of conventional signal detector was improved using the character of signal superimposition, which is expressed, as the time-delay difference between times of trailing and forward edges in offset interference signal is equal to the length of the sending signal, to improve signal detec?tion ability and time-delay estimation precision, reduce multi-path influence on chronometric precision and modify the systematic performance. The simulated results show that the method is effective.

A Dual-band Color Imaging System for Visible and Thermal IR Images Based on Color Transfer in YUV Color Space

SHI Shi-ming, WANG Ling-xue, JIN Wei-qi,ZHAO Yuan-meng

2009, 30(1):  30-35.  doi:10.3969/j.issn.1000-1093.2009.01.007

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A dual channel real-time image fusion system based on DSP/FPGA for color night vision was designed. The visible and thermal IR images were fused into a color image through Cyclone H FPGA made by Altera Co. Ltd.，the color transfer in YUV color space was executed by TMS320DM642 made with TI Co. Ltd.，to transfer the color information of a day-time target image to the fusion im?age, which more approaches nature color and possibly reflects rich scene information. The principles, the structure, characters and the functions of the system were expounded. It was proved Dy an experi?ment that the system can realize effecive color transfer in real time against the background of woods and land.

Blind Estimation of Frequency Offset and Symbol Timing Based on Band-edge Component Maximization

SHAO Shi-cai, XU Xiao-dong, LU You-rong,DAI Xu-chu, XU Pei-xia

2009, 30(1):  36-42.  doi:10.3969/j.issn.1000-1093.2009.01.008

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A new blind estimation algorithm for frequency offset and symbol timing was proposed based on the maximization of the spectrum of the sampled received signal at the band edge. The effect of fre?quency offset on the performance of the band-edge timing algorithm was analyzed, and then the conju?gate autocorrelation based frequency offset estimation algorithm, which is iteratively implemented, was effectively combined with the timing estimation algorithm to realize the joint blind estimation of the frequency offset and the symbol timing under the condition of larger frequency offset. Theoretic analy?ses and computer simulations show that the proposed algorithm needs no a priori knowledge of the modulation type or the multiple attenuation channel, and possesses the characteristics of fast conver?gence and low computational complexity.

Strapdown Homing Guided and Direct Force Control System Design for Low Altitude Interception Missile

SONG Jian-mei, SUN Song-bin

2009, 30(1):  43-48.  doi:10.3969/j.issn.1000-1093.2009.01.009

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A design method of strapdown homing guidance and direct force control system for low alti?tude interception missile was presented. An integral proportional navigation law for the missile was de?duced by the estimated trajectory angle in real-time based on the kinetic features of the direct force con?trol missile. In order to control the missile accurately, the calculating formulas of fire number and fire angle of impulse motors were deduced based on the principle of equaling impulse. The simulated results show that the design method is correct and feasible, the designed system can satisfy the requirements of the missile in respects of low cost, quick response and high accuracy.

Research on Optimizing Scheduling of Multi-satellite Joint Imaging Based on Stochastic Search and Relaxation Methods

JIN Xiaoshan，LI Jun, WANG Jun, JING Ning

2009, 30(1):  49-55.  doi:10.3969/j.issn.1000-1093.2009.01.010

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Joint imaging with multi-satellite is an effective approach to make up the deficiency in re?visiting cycle and range with single satellite. A mathematical programming model of optimizing scheduling of multi-satellite joint imaging was built, a Lagrangean relaxation method based on a max- weighted path research method in the constraint graph and a sub-gradient optimizing method was pro?posed to obtain tight upper bound of the problem. A satellite assignment algorithm based on imaging task sequence was proposed to solve imaging task assignment among multi-satellites, the best imaging task sequence was searched by the stochastic hill-climbing algorithm to obtain feasible optimizing scheduling of multi-satellite joint imaging. The simulated results show that the proposed method is ef?fective .

Generalized Mathematical Modelings and simulations of Pursuit Guidance Method

QIANG Sheng, LONG Han, SHEN Zhen,YI Dong-yun

2009, 30(1):  56-62.  doi:10.3969/j.issn.1000-1093.2009.01.011

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The lateral intercept was proposed to extend a discussion on a pursuit navigation method; the analysis and proof of influence of the pursuit navigation method on the trajectory were theoretically given; 3D solid combined navigation method was established by the generalized proportional navigation method and the pursuit navigation one to make the navigation scheme more flexible and effective. The intercept process was simulated by the combined navigation method. The simulated results show that the method is simple and convenietn to use and has practical value.

An Overall Adaptive Filtering Algorithm for Tracking Maneuvering Target

FAN Guochuang, DAI Ya-ping, XU Xiang-yang

2009, 30(1):  63-68.  doi:10.3969/j.issn.1000-1093.2009.01.012

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A modified truncation Gauss probability density model was set up based on the truncation Gauss probability density model, the algorithm of overall adaptive filtering (OAF) for tracking ma?neuvering target was proposed by combining the modified truncation Gauss probability density model with adaptive velocity estimation model. In the OAF algorithm, the preestablishing of the maximum acceleration is avoided and the maneuvering frequency is adjusted adaptively. The system noise covari?ance and the maneuvering frequency were fused by BP neural network. The fused system covariance was gotten by regulating the veight value of neural network online, to reduce precision loss due to reg?ulating parameter improperly. The results of theoretical analyse and simulations show that the OAF al?gorithm can improve the precision of system by 49.Ol% and 48.34% respectively in tracking maneu?vering and nonmaneuvering targets, in comparison with only adaptive velocity estimation algorithm.

Study on Fault uiagnosis and Prognosis Methods Based on hidden Semi-Markov Model

HU Hai-feng, AN Mao-chun, QIN Guo-jun, HU Niao-qing

2009, 30(1):  69-75.  doi:10.3969/j.issn.1000-1093.2009.01.013

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A hidden semi-Markov model (HSMM) is an extension of hidden Markov model (HMM), designed to remove the exponential distribution of the state durations assumed in HMM by adding ex?plicit time duration parameters. Besides HSMM powerful capability of pattern classification, it allows modeling the time duration of hidden states more reasonably, therefore, it can be used for either fault diagnosis or fault prognosis. A unified framework for both fault diagnosis and prognosis based on HSMM was presented. An efficient recursive algorithm which can reduce the computation complexity and storage of HSMM was introduced into HSMM model to facilitate the proposed HSMM-based diag?nosis and prognosis. The proposed methods were applied to fault diagnosis of helicopter gearbox bear?ings and the remaining useful life (RUL) prediction of GaAs lasers respectively. The results show the validity of the methods.

Optimization of Calibration Interval for Automatic Test System Based on Support Vector Regression

SUN Qun, ZHAO Ying, MENG Xiaofeng

2009, 30(1):  76-80.  doi:10.3969/j.issn.1000-1093.2009.01.014

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To optimize the calibration interval of automatic test system (ATS), a metrological architec?ture was established and the characters of calibration inspection data were analyzed, and a predicted model of calibration interval based on support vector regression (SvR) was proposed. The simulated results show that the model has higher prediction precision than normal prediction models, mitigates the contradiction between insufficient and excess metrics under the condition of small sample of calibra?tion inspection data.

A Feature Selection Method Based on Adaptive simulated Annealing Genetic Algorithm

ZHANG Hao, TAO Ran, LI Zhi-yong,DU Hua

2009, 30(1):  81-85.  doi:10.3969/j.issn.1000-1093.2009.01.015

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feature selection is one of important problems in machine learning and pattern recognition areas. For high demensian data, feature dimension can be decreased under the condition of ensuring data integrity and classification accuracy can be improved by feature selection. A feature selection method based on adaptive simulated annealing genetic algorithm was proposed, which embeds the sim?ulated annealing algorithm in the circle of adaptive genetic algorithm and uses the feature that simulat?ed annealing algorithm has the strong ability of local search and makes searching process avoid sinking into the local optimal solution, to solve the shortcomings of slow convergence speed and high time com?plexity. The experiment results show that the method can guarantee the correct rate of classification and improve the efficiency of feature selection.

Contrast of Fault Mode Analyses of CNC Machine Tools between the Chinese-Built and the German

JIA Zhi-cheng, HU Zhong-xiang, SHEN Gui-xiang,WANG Gui-ping

2009, 30(1):  86-90.  doi:10.3969/j.issn.1000-1093.2009.01.016

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To alter the status quo that the iaiiure rate of the Chinese-built computer numerical control (CNC) machine tools is higher than that of the CNC machine tools produced by developed countries, their tracking tests on the spot and fault mode analyses were performed. The comparison of the fault modes shows that the former is different from the latter evidently in fault modes; the main factors causing the difference are found to provide an effective method for improving reliability of the former.

Research on Life Prognosis Method for Electronics Based on Dynamic Damage and Optimization AR Model

LV Ke-hong, QIU Jing, LIU Guan-jun

2009, 30(1):  91-95.  doi:10.3969/j.issn.1000-1093.2009.01.017

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It has been already realized that the main external factor of electronics degradation or devia?tion from an expected normal condition is the time stress such as vibration, temperature, humidity etc. For the existent deficiency of a direct lift prognosis method based on single point damage information,a new life prognosis method was proposed by the recursive life prognosis model and the optimization auto-regression model, the life prognosis process and the specific algorithm were given in detail. Tak?ing the power MOSFET of a certain type of missile launching vehicle as an example, the proposed method was demonstrated. The results show that the real degradation trend and the influence of abrupt life changing induced with accident on life prgnosis are taken into account by the method.

Research on Modeling and Experiment of Ellipsoidal Surface Lapping Tool Using Bend Forming Method

SHANG Chun-min, ZHANG Dong-mei, YANG Jian-dong,FAN Jing-feng

2009, 30(1):  96-99.  doi:10.3969/j.issn.1000-1093.2009.01.018

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To resolve the difficulty of lapping ellipsoidal surface, a new method of lapping it using the bend forming lapping tool was proposed. Based on the elasticity distortion characteristic of some mate?rial under the action of a bending moment, a mathematical model of bend forming of lapping tool was established using the mechanics and the higher mathematics knowledge. The expression of width func?tion of lapping tool was deduced, to make the generatrix of lapping tool after bend forming consist with that of the worKpiece profile. A lapping tool system was designed according to the calculating example, and its bending experiment was performed. The experimented results show that the maximum error of surface shape is 0.141 8 μm which can satisfy the precision requirement of the most workpieces.

The Fractal Dimension of Cylindrical Surfaces for Abrasive Jet rinishing Restricted by Grinding Wheel

LIU Feng, GONG Ya-dong, SHAN Yu-qiao, CAI Guang-qi

2009, 30(1):  100-104.  doi:10.3969/j.issn.1000-1093.2009.01.019

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The surfaces ground and finished with abrasive jet were investigated by the relations of D —Ra, D-Rq and D-supporting rate. The experiments were performed by an external cylindrical grinder type MBl332A, the specimens made from 45# steel with surface roughness of Ra =O.6 μm, a scanning electronic microscope (SEM) used for observing the machined surface morphology and a pro- iilometer type Micromesvre 2 used for measuring the microcosmic geometry parameters. The experi?mented results show that the geometry structure of micro-morphology of machined surface can be bet?ter evaluated by the linear relation of D vs. Rq to complement the insufficiency of traditional roughness parameters; the variable laws of normalization curves of Ra vs. supporting rate consist with those of Ra vs. D, which can replace supporting rate for grinding process and abrasive jet finishing process.

Research on EDM Technology Experimentation of 4Cr5MoSiV

WEN Wu, WANG Xi-bin, LONG Zhen-hai，JI Yong-hong

2009, 30(1):  105-109.  doi:10.3969/j.issn.1000-1093.2009.01.020

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The technology experimentations of EDM for 4Cr5MoSiV were compositely performed by single factor and orthogonal methods. On the basis of analyzing EDM characteristics, the influences of electric parameters and interaction on material removal rate, electrode loss and proportion of relative loss were examined, the mechanism of Jt^DM was investigated. The examined and investigated results show that the influence of pulse width on proportion of relative loss is larger than that of peak current and machining voltage at machined material of 4Cr5MoSiV, peak current of 4 ?24 A, pulse width of 25 ?400 μs, machining voltage of 80 ?200 V, electrode material of industrial copper of type Tl with purity 99.95 % and machining in negative polarity; the higher material removal rate is obtained by choosing suitable pulse width at low proportion of electrode loss.

Short Papers

The Model of Combat Unit Spares Availability Based on BCMP Queuing Network

ZHANG Jian-jun, LIU Fang, ZHANG Tao,GUO Bo

2009, 30(1):  110-113.  doi:10.3969/j.issn.1000-1093.2009.01.021

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The spare availability is one of the important indexes of evaluating maintenance support abil?ity for combat unit. On the basis of analyzing the hierarchy and the maintenance flow of combat unit and its support system, the model of evaluating combat unit spare supportability was established based on BCMP quening network, the solution method of the model was given by multi-class marginal distri?bution analysis. A study case and its analysis results prove that the model and the solution method are useful and effective.

Research Notes

LMI-based Robust Stability Analysis for Uncertain Delayed Neural Networks

LINZhi-wei, QIU Ji-qing, YANG Hong-jiu, KAN Jun

2009, 30(1):  114-118.  doi:10.3969/j.issn.1000-1093.2009.01.022

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The problem of robust stability for uncertain neural networks with time-varying delays was investigated. The norm-bounded uncertainties are included in the system matrices. The constraint on time-varying delays is removed, which means that a fast time-varying delay is admissible. Some new stability criteria which are correlated with time delays and its derivatives were presented by using Lya- punov-Krasovskii function and linear matrix ineguality(LMI) approaches. A numerical example was given to illustrate the effectiveness and less conservative of the developed techniques.

Comparison of Several Algorithms for Maritime Moving Target Search by Satellite

Cl Yuan-zhuo, XU Yi-fan, TAN Yue-jin

2009, 30(1):  119-125.  doi:10.3969/j.issn.1000-1093.2009.01.023

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Maritime moving target search by satellite is to seek the optimal reconnaissance plan to fina the maximum targets at the least time constrained by satellite platform and remote sensor capability. Five search algorithms for maritime moving target search were put forward namely random selection al?gorithm (RSA), maximum detection probability grid algorithm (MDPGA), maximum sum of detec-tion probability algorithm (MSDPA), maximum coverage algorithm (MCA)and maximum change of information entropy algorithm (MCIEA) . A simulated scenario was established by high fidelity satel?lite orDit data, the simulation of maritime moving tanget search was peformed by the mentioned five search algorithms under the conditions of different initialized parameters, the corresponding simulation performance statistic results were given, and the characteristics of different algorithms and the perfor?mance difference among the algorithms were summaried.

Study on Performances of EPDM Heat Insulation Materials with Octaphenylsilsesquioxane

GAO Jun-chi, MA Lin, YANG Rong-jie, HE Ji-yu

2009, 30(1):  126-128.  doi:10.3969/j.issn.1000-1093.2009.01.024

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Octaphenylsilsesquioxane (OPS) was used in the insulator materials based on ethylene propylene diene monomer (EPDM) rubber. The mechanical properties, linear ablative rate, smoke production and density of the EPDM/OPS heat insulation materials were determined. Compared with the EPDM heat insulation materials without OPS, part replacement of ammonium phosphate (APP) by OPS decreases linear ablative rate, smoke production and density, ana improves mechanical properties.