Table of Content

30 September 2008, Volume 29 Issue 9

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Paper

Computational Fluid Dynamics Analysis for Flow Field and Temperature Field of Tank Exhaust

BI Xiao-ping, YANG Yu

2008, 29(9):  1025-1028.  doi:10.3969/j.issn.1000-1093.2008.09.001

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A computational fluid dynamics (CFD) models were constructed for exhaust flow and heat transfer of tank. Their three-dimensional numerical analyses were accomplished by applying FLU- ENT. The gas temperature and the pressure at exhaust pipe exit section were tested and their analysed values accord, with the test data well. Detailed distributing characteristic for flow field and temperature field, of tank exhaust and. the effect of environment temperature and wind, speed on exhaust were ob- tained through CFD analysis. These results can provide the basis for investigating infrared radiation characteristic of tank exhaust.

A Study of Catalyzing Thermal Decomposition and Combustion of AP/HTPB Propellant with Nano Cu/ CNTs

LIU Yong, JIANG Wei, LIU Jian-xun, WANG Yi, LIU Guan-peng, LI Feng-sheng

2008, 29(9):  1029-1033.  doi:10.3969/j.issn.1000-1093.2008.09.002

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The nano Cu/CNTs composite catalyst were prepared by liquid reductive deposition method and using the carbon nanotubes as the carrier, its microstructure and composition of nano Cu/ CNTs were characterized by SEM, XRD and XPS. The catalytic performance of nano Cu/CNTs in the ther?mal decomposition and combustion of AP/HI PB propellant was investigated. The result shows that Cu/CNTs can remarkably decrease the high temperature decomposition peaks, evidently increase the aooarent decomposition heat and improve the burning rate and decrease the pressure exponent for AP/ Hl PB propellant effectively. The catalytic mechanism of nano Cu/CNTs composite on the thermal de?composition and combustion of AP/ Hl PB propellant was tentatively explored.

Influence Factors of Preparation of Ultra-fine PYX by Solvent and Non-solvent Technique

WANG Bao-guo, CHEN Ya-fang, ZHANG Jing-lin

2008, 29(9):  1034-1038.  doi:10.3969/j.issn.1000-1093.2008.09.003

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The ultra-fine PYX which average particle size is 1038.0 nm is prepared by solvent-non-sol-vent technique. Some of the technical conditions and drying method which have an effect on the parti?cle size of PYX were studied. The major influence factors were studied by means of single factor test and orthogonal one. Both energy output and impact sensitivity before and after ultra-fine FYX were tested. Optimized tecnnological conditions were obtained, such as temperature contrast 70 °C between solution and non-solvent, solution concentration 0.08 g/mL, mixing speed 1600 r/min, adding rate 1.0 mL/min and vacuum refrigerant drying. Experiment results show that the order of factors affect?ing particle size of PYX is drying method, solution concentration, temperature contrast, mixing speed, solution added rate. Furthermore, drying method is the most important factor to affect particle size of the product. The steel engraving numerical number of the ultra-fine PYX is higher than that of its material by 9.9%, its characteristic drop-high is 2.5 times of that of its material.

Differential Power Analysis Attacks for Data Encryption Standard Cryptographic Systems

CHU Jie, ZHAO Qiang, DING Guo-liang,DENG Gao-ming

2008, 29(9):  1039-1043.  doi:10.3969/j.issn.1000-1093.2008.09.004

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In order to open out the information leakage caused by the power consumption of running cryptographic system, the data power consumption correlation of static CMOS gates was analyzed. The differential power analysis (DPA) attacks against the data encryption standard (DES) crysto- graphic system realized with AT89C52 microcomputer were designed and implemented. A power con?sumption model of static CMOS gates in registers was offered. It explained how the selection function D divided the power consumption curves into two sets with different power consumption characters and makes the way to deduce the power consumption characters from the data and vice versa more clear. 48-bit key of the round 16 of DES was detected in DPA attacks. The result shows that DES cryptographic systems without special protective measures are not strong enough to resist DPA attacks because of the data-power correlation of static CMOS gates.

A Joint Method of Zero-crossing Detection and Energy Detection

LIU Ke-man, XIANG Jing-lin, HOU Tie-shuang, CHEN Shao-hua

2008, 29(9):  1044-1048.  doi:10.3969/j.issn.1000-1093.2008.09.005

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A joint method of signal detection for detecting the weak signal of passive acoustic fuze was presented by the variations of the mean values of zero crossings over a unit time interval and the broad?band energy amplitude based on noise waveform caused with target appearance, to improve the signal detecting performance. The experimental results taken from the sea show that the proposed method can enhance the target signal by 5 — 8 dB compared with zero crossing detection one, suppress the addi?tive Gaussian white noise by 4 - 7 dB compared with the energy detection one, and has good prospects for applying it to an underwater acoustic fuze system.

Support Vector Data Description for Fast Anomaly Detection in Hyperspectral Imagery Based on Sample Segmentation

GHEN De-rong, GONG Jiu-lu, CHEN Qian, CAO Xu-ping

2008, 29(9):  1049-1053.  doi:10.3969/j.issn.1000-1093.2008.09.006

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Support vector data description (SVDD) is particularly good at anomaly detection in hyper- spectral imagery but has extremely nigh computational complexity which limits the real-time imple?mentation. To reduce the computational cost of support vector extraction, a fast ^VDD method was proposed by dividing training samples into subsets. The mathematic models of the support vector com?putation complexity and the sample segmentation subset amount were established, the optimum choos?ing method of the subset amount was given. The optimal segmentation method of target and back?ground windows was proposed, by segmenting background widow into subsets whose shape and size are the same as that of target window, with which only a half of training sample is updated when target window moves one step to reduce the computation amount of extracting support vector from training samples in whole image. The simulation results on HYMAP data demonstrate that the computation time used by the proposed method is less than 10% of that used by SVDD with different sizes of images.

Optimal Image Watermarking Technique Based on Genetic Algorithm

ZHONG Ning, HE Zun-wen, KUANG Jing-ming

2008, 29(9):  1054-1058.  doi:10.3969/j.issn.1000-1093.2008.09.007

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The robustness and the invisibility are important properties in an efficient image watermark?ing system. Since they conflict with each other, a watermarking system is difficult to satisfy them at same time. One good scheme to resolve this dilemma is to apply genetic algorithm (GA) to obtain the optimized solution. An optimal image watermarking technique based on GA was proposed. Arnold transform was utilized to obtain the scrambled watermark, and then the watermark embedding and ex?traction were implemented in digital wavelet transform (IjWT) domain. The robustness and the invis?ibility of the watermarking system were optimized comprehensively by UrA searching optimal parame?ters of embedding strength and times of Arnold transform. Simulated results show that both water?mark robustness and invisibility can be achieved under different attack schemes.

Maximum Likelihood Elevation Extraction Technique for Radar Low-altitude Target

LV Shaoyu, ZHAN Rong-hui, WAN Jian-wei

2008, 29(9):  1059-1062.  doi:10.3969/j.issn.1000-1093.2008.09.008

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The effects of the jamming of sea-surface multi-path echo signals for mono-pulse radar with angular measurement system on elevation measurement of low-altitude target are too largo to attain the precision requirement of exterior ballistics in shooting range. For improving the measured elevation precision of low-altitude target, the elevation parameters of low-altitude target were extracted from the stored video signal of radar system by the maximum likelihood estimate algorithm. I he calculated re?sults show that the algorithm can remarkably improve the measured precision of elevation and provide basis for testing and deciding in shooting range.

On Reliability Modeling for Wireless Sensor Networks

ZHOU Qiang, DU Yu-qing, XIONG Hua-gang

2008, 29(9):  1063-1068.  doi:10.3969/j.issn.1000-1093.2008.09.009

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Taking aim at the features of wireless sensor network (WSN) system, such as large scale, easy iauure and distributive type, the network model and the task model of WSN system were given, the reliability model of the system based on the task was established, to realize the reliability estimation from a single task to the whole system. Taking aim at the representative cluster topology structure of WSN，a modeling example was given. The presented method provides basis and reference for the task division and the selection and the optimization of topology structure in the phase of WSN system de?sign.

Research and Implementation of Estimation Method for Tactical Internet Performance in a Rencounter Scenario

WU Di, HE Zhao-xiang, ZHAO Xiao gang,YIN Fu-Iiang, LI Ming

2008, 29(9):  1069-1073.  doi:10.3969/j.issn.1000-1093.2008.09.010

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Tactical internet (TI) is quite different from the civil mobile Ad hoc network, due to the special worKing environment. However, most of the researches on TI ignore these special battlefieldJ s factors, such as terrain, tactical action, etc. rtence, a new method to analyze the effects of the factors on TI was proposed. The tactical communication in a rencounter scenario with fish-eye state routing (tSR) protocol was simulated by the tactical communication simulation system (TCSS) software de?signed and programmed autonomously. The simulation results indicate that those special factors have significant influence on the efficiency of the routing protocol in Ad hoc network, and the experiment data can be used as a reference to design a TI communication system.

Mechanism Analysis of Zero Displacement Movement of LLL Sight Device Based on Vibration Experimental Condition,

GAO You-tang, QIU Ya-feng, TIAN Si,CHANG Ben-kang

2008, 29(9):  1074-1077.  doi:10.3969/j.issn.1000-1093.2008.09.011

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For solving the zero displacement movement problem of low-level-light(LLL)sight device, the regulating structure of LLL sight device reticle was given. The movement mechanism under the action of vibration experimental load was revealed by analyzing the applied force of the adjusting screw rod and calculating the accumulated value of the circumference torque Tz within the range of the equiv?alent friction angle ρ. Type CMETSO05 detection system of computer-controlled multi-environment test of LLL sight device with the measure precision ≤0.05 mil and the measure range ≥40 mil was developed and applied actually. The measured result shows that the measured data are reliable and pro?vide theoretical basis for producing other direct-vision sight device.

Automatic Identification of Interferences in Direct Sequence Spread Spectrum Communication System

YANG Xiao-ming, TAO Ran

2008, 29(9):  1078-1082.  doi:10.3969/j.issn.1000-1093.2008.09.012

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Analyzing the interference environment in which the communications system is located can help both the participants in communication take corresponding anti-interference measurements for specific types of interference. The automatic identifideation of the interferences in the direct sequence spread spectrum (DSSS) communication system was proposed by a set of robust feature parameters which can jointly extract the characteristics of the interferences in time, frequency and time-frequency domains at the condition of no prior knowledge of the interferences. The simulated result shows that the correct identification rate of various interference signals based on the method proposed is reasonably high in the case of different interference-to-signal ratio(ISR) and signal-to-noise ratio(SNR).

Modeling and Simulation of Missile Vertical Launching System Based on Flexible Multi-body Dynamics

XU Yue, TIAN Ai-mei, ZHANG Zhen-peng,CHEN Xiao-qing

2008, 29(9):  1083-1087.  doi:10.3969/j.issn.1000-1093.2008.09.013

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A flexible multi-body dynamic model of ship-based missile vertical launching system (VLS) was built on the platform of virtual prototype technology (VPT)，based on finite element method (FEM) and improved fixed-interface substructure modal synthesis. The dynamic simulation of the flexible model was performed, and the results were compared with that of the rigid model. The trajec?tory and attitude deviations during launching were gained. The analysis of effects of flexible deforma?tion on initial trajectory characteristics and launch security was completed.

Geomagnetic Autonomous Navigation Technology of Cruise Missile Based on the Unscented Kalman Filter

SHI Gui-guo, ZHOU Jun, GE Zhi-Iei

2008, 29(9):  1088-1093.  doi:10.3969/j.issn.1000-1093.2008.09.014

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In order to overcome the deficiencies of current navigation technologies of cruise missile, a navigation method using geomagnetic field information was presented. A navigation filter based on the unscented Kalman I liter algorithm was designed by taking the international geomagnetic reference field as the geomagnetic field model, the geomagnetic field vectors and the flight height as observed vari?ables, and combining the missile motion model with the geomagnetic field model. The observability and observable degree of the navigation system were analyzed in detail by the observability matrix and the singular value decomposition method. The location and speed of cruise missile were simulated by the navigation filter. The simulated results show that the navigation precision with high order geo?magnetic field model is better than that with low order geomagnetic field model; the smaller the ob?served noise intensity is, the higher the navigation precision is. The method provides better filter con?vergence, stability and moderate navigation precision for autonomous navigation in the initial and mid?course phase guidances of cruise missile.

Location Model of Dual Triangle Acoustic Target Based on Information Fusion

SUN Shu-xue, LV Yan-xin, GU Xiao-hui,HUANG Zheng-xiang

2008, 29(9):  1094-1098.  doi:10.3969/j.issn.1000-1093.2008.09.015

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The coordinate values and the velocity of hitting point ware simulated by a dual triangle a- coustic target model and an information fusion algorithm through detected shock wave signal caused with supersonic projectile in the course of flying. The measurement accuracy was improved by data fuse and experimental calibration. The simulation results show that the method has better efficiency and is suited for firing training in proving ground.

Optimal Design of ^oiid Rocket Motor Filament-wound Case Based on Netting Theory

HU Kuan, SONG Bi-feng, CHANG Xin-long,ZHANG Lin

2008, 29(9):  1099-1103.  doi:10.3969/j.issn.1000-1093.2008.09.016

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Based on filament-wound case basic equations, which were deduced with netting theory ac?cording to burst pressure, taking the structural sizes and the technological parameters as constraint conditions, taking the case mass as constraint object, the design variables were optimized, such as ma?terial density and strength, wind angle of case section, radius of polar hole, by a linear multi-step method and a complex. A numerical example was given. The calculated result indicates that specific strength is the most important factor, which affects mass of the case.

The Dynamic Fault Tree Analysis Method Based on Markov Chain

ZHU Zheng-fu，LI Chang-fu，HE En-shan, YANG Chun-hua

2008, 29(9):  1104-1107.  doi:10.3969/j.issn.1000-1093.2008.09.017

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A dynamic fault tree analysis (DFTA) method based on Markov chain was proposed. Its principle is disassembling the state transform figures into several state transform chains firstly, and the chain probability formula can be got according to the length ox tne chains. Then the dynamic fault tree failure probability can be obtained by adding each chain probability. For the given state transform fig?ures, the reliability analytical formula of Dt IA based on the consecutive parameter Markov chain was proposed and verified. In comparison with the conventional methods, this method needn’ t solve the differential equation, can be applied to engineering easily.

Investigation on Dynamic Properties of Reinforced Concrete with Regular Steel Lattice Microstructure

NING Jian-guo, LU Jing-han, JIANG Fang, SUN Yuan-xiang

2008, 29(9):  1108-1113.  doi:10.3969/j.issn.1000-1093.2008.09.018

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The dynamic compressive properties of reinforced concrete were investigated experimentally by one-stage light gas gun. In order to get the distributions of other mechanical parameters in the spec?imen, the experimental data were processed by the Lagrangian analytical method. The experimental results show that there is no improvement of dynamic compressive behavior of tne concrete by adding reinforcing steel web in the range of reinforced ratio; however, the dynamic compressive strength and ductibility of the reinforced concrete increase greatly when the reinforced ratio increases. Thus it is considered that the dynamic behavior of reinforced concrete is greatly influenced by the reinforcement of steel and the increase of initial damage by adding steel web to the concrete. Base on these observa?tions and theoretical work maae by previous researchers, a dynamic constitutive relation of reinforced concrete including damage evolution was established. Theoretical estimation results agree reasonably well with the experimental data.

Bayesian Analyses in Small Sample circumstance for Assessment of Weapon Performance

LIU Jun, LI Qing-min, ZHANG Zhi-hua

2008, 29(9):  1114-1117.  doi:10.3969/j.issn.1000-1093.2008.09.019

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Abundant test data are required in assessment of weapon performance. When real test data are insufncient, Bayesian analyses in small sample circumstance should be considered and test data should be provided by simulations. An improved method based on complete probability was proposed by considering the confidence of simulation system reasonably to avoid the simulated test data obliterat?ing the real test data. The application to the assessment of performance of a certain new underwater weapon proved that the method has better property.

Dynamical Characteristic and Experimental Analysis for Thin-wall Part of Aviation in the Milling

WU Qiong, ZHANG Yi-du, ZHANG Hong-wei,ZHAO Xiao-ci

2008, 29(9):  1118-1122.  doi:10.3969/j.issn.1000-1093.2008.09.020

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Based on the experiment of cutting force coefficient identification, the mathematical model of cutting force was established. I he formula and the curve of the “—” shaped thin-wall part ampli?tude responses were obtained by combining finite element dynamic analysis with milling vibration mathematical model and extended to the complex thin-wall parts of aviation. According to the relation?ship of rotate speed and frequency of the workpiece, the program of parameterized dynamical charac?teristic analysis was programed to realize optimization of the milling parameters of thin-wall part.

Intelligent Fault Diagnosis Method for Complex Equipment Based on Rough Decision Tree Model

ZHANG Chao, MA Cun-bao, SONG Dong,XU Jia-dong

2008, 29(9):  1123-1128.  doi:10.3969/j.issn.1000-1093.2008.09.021

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A rough decision tree-based intelligent fault diagnosis method for complex equipment was proposed. The original diagnostic decision table was built by using the rough set theory; the continu?ous conditional attributes were discretized by using the minimum entropy-based algorithm; the redun?dancy conditional attributes were reduced by utilizing the discernibility matrix-based algorithm, and the optimal attribute reduction is established by using the maximum cluster ratio principle; the diag?nostic decision tree was constructed by utilizing the C4.5 algorithm. The fault diagnosis of an example was made by the proposed method. The diagnosed results show that the proposed method can effec?tively decrease the workload of feature datum extraction, recognize the fault patterns rapidly and accu?rately, has better engineering practicality than the rough set-based, the rough decision-based and the C4 . 5-based metKod.

An Experimental Study of Effect of Pin Fin Geometry Construction on Heat Transfer in Turbine Blade Trailing Edge

LIU Yang, LI Xiang-li, YANG Wei-hua

2008, 29(9):  1129-1132.  doi:10.3969/j.issn.1000-1093.2008.09.022

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In order to study the influence of the pin fin geometry construction on the convective heat transfer characteristics in turbine blade trailing edge, four Rinds of pin fin were designed and the film cooling characteristics of them were experimentally studied. The wall temperature was measured by means of infrared camera. The regularity of convective heat transfer characteristics was obtained at the difference of geometry construction of the pin fines and the blow ratios. The results show convective heat transfer characteristic with the water drop-shaped I pin fin is best in comparison with others at the lower blow ratio, that with the column-shaped pin fin is better as the higher blow ratio, that with tne water drop-shaped II pin fin is the smallest. At the same location of the trailing edge, convective coef?ficient is increased with the growth of blow ratio.

Experimental Techniques and Analysis

A Study on the compatibility of Hydrogen Storage Alloy Incendiary Agent with Some Common Energetic Components of Solid Propellants

LIU Jing-ru, LUO Yun-jun

2008, 29(9):  1133-1136.  doi:10.3969/j.issn.1000-1093.2008.09.023

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Hydrogen storage alloy is a kind of functional material which can store hydrogen atoms in crystal lattices in great quantities and be made into a new type of incendiary agent as an important component of solid propellant. The compatibility of hydrogen storage alloy incendiary agent with some common energetic components of solid propellants such as ammonium perchlorate (AP)，cy- clotrimethylenetrinitramine(RDX), hexanitrohexaazaisowurtzitane( CL-20 ), I/ 1-NG/DEGDN mixture (NG + DEGDN) and nitrocellulose(NC)was studied by using DSC method. The results show that the binary systems of hydrogen storage alloy incendiary agent with all energetic components measured are compatible.

Study on Color Reaction of DBC-arsenazo with Chromium(Ⅲ)

ZHAI Qing-zhou, JIAO De-zhi

2008, 29(9):  1137-1140.  doi:10.3969/j.issn.1000-1093.2008.09.024

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In a buffer medium of Clark-Lubs at pH 2.0, DBC-arsenazo reacts with chromium(Ⅲ ) to form a violet-red complex with a composition of 1:1. The maximum absorption wavelength of the complex is 600 nm. The apparent molar absorptivity of the method is ε600 nm = 1.8 / X 104 L·mol-1 ? cm-1 . Beer’s law is followed over the concentration range of 0 ?3 mg/L of chromium (Ⅲ）? The method is successfully used in determining chromium in cabbage samples. The analytical results ac- cordes with those of contrast method atomic absorption spectrometry. The recovery of standard addi?tion of the method for the determination of chromium was 98.0 % ~ 102 % . The relative standard de?viation of thirteen replicate determinations was 1.6% ~2.5% .

Research Notes

Research on the Modern Testing System of Exit Pupil Diameter, Distance and Magnification of Optical Sighting Telescope

YANG Rui-ning, AN Zhi-yong, GAO Wei-guo,XIANG Yang, LIU Li-xin

2008, 29(9):  1141-1144.  doi:10.3969/j.issn.1000-1093.2008.09.025

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Taking aim at the modern testing requirement of exit pupil diameter, distance and magnifi?cation of optical sighting telescope, based on the traditional testing principles and methods, the pro?posed system was designed by the modern optical measuring principle and method, such as the CCD shooting, precision machinery, optics and computer control and image processing. In the testing pro?cess, the resolution of image and the location accuracy of target image were greatly improved by the subdivision technology. The testing accuracy of diameter and distance of exit pupil is 0.01 mm, the testing range is I ?100 mm, and the testing accuracy of magnification is less than I %，and the eye fa?tigue strength is greatly lightened.

INS Initial Alignment Based on L2 Robust Control Theory

DAI Shao-zhong, WANG Bo

2008, 29(9):  1145-1148.  doi:10.3969/j.issn.1000-1093.2008.09.026

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A new method of INS initial alignment based on L2 robust control theory was proposed. Based on robust optimal control theory, by configuring auxiliary feedback control variable, the dynam?ic performance of the system was improved, also the alignment time was shortened. The simulated re-sult shows that compared with that of traditional Kalman filter, the level misalignment angle can be es?timated with the same accuracy, while the estimated accuracy of the azimuth misalignment angle is greatly improved by one order of magnitude, the alignment time is shortened from more than 100 s to equal or less than 10 s.

Layout Optimization of Cockpit Based on Human Comfort

WANG Rui, ZHUANG Da-min

2008, 29(9):  1149-1152.  doi:10.3969/j.issn.1000-1093.2008.09.027

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According to the manhood anthropometric data and Lagrange equation, the dynamics model for upper limb’s steering was established. Using the strength model derived from NASA experimental data and the actual installation criterion of cockpit, the operation movement of the crew was simulat?ed. When work load is given, the actual joints torques can be calculated by inverse dynamic analysis, and then the three-dimension comfortable manipulation area can be acquired according to given comfort criterion. When the location of stick is appointed, joints’ torques varies with work load. I he maximal operating force of end effector equals worKload when a certain joint torque ascends to its extremum. The three- dimension comfortable manipulation area should meet the ultimate force necessary to steer. This method can be applied to pilots，ergonomics evaluation and optimizing tne design of cockpit layout.