Table of Content

01 December 2012, Volume 33 Issue 12

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Paper

Research on Dynamic Control of Proton Exchange Membrane Fuel Cell System

MA Xiao-jun, KE Rong-shuo, XU Shi-meng, YAN Zhi-feng, YUAN-Dong

2012, 33(12):  1409-1415.  doi:10.3969/j.issn.1000-1093.2012.12.001

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With the advantages of low noise, low infrared signature and high dependability, the fuel cells can be used for the military vehicles and field power supply. The reaction characteristics of proton exchange membrane fuel cell (PEMFC) system are affected by selfconfiguration, environment and other factors. For the limit of sensor technology, the inner temperature and humidity of the fuel system can’t be measured immediately, and its reaction characteristics are different every time. System model is difficult to build, its inner humidity can’t be well controlled using a traditional control method. For 3 kW PEMFC system, a simple control system was built to control the humidity dynamically, which keeps the humidity changing up and down alternately in dynamic threshold. The limit of system model is get rid of by this method, avoiding the humidity excursion caused by steadily control. Finally the feasibility of this control method was validated through experiment.

Weight Analysis in the Effect of Combustion System Parameters on Combustion Performance in a High Speed Direct Injection Diesel Engine

YU Yu-song, LI Guo-xiu, ZHANG Jing, YUAN Ye

2012, 33(12):  1416-1422.  doi:10.3969/j.issn.1000-1093.2012.12.002

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In order to explore the mechanism of highspeed diesel engine combustion system parameters on the combustion properties, the matching laws between fuel injection system parameters and combustion chamber structures in high speed direct injection (HSDI) diesel engine was studied by using threedimensional CFD numerical simulation method. The spatial distribution of fuel vapour and characteristics of fuel /air mixing were analyzed. In order to quantitatively describe the performance of fuel/air mixing, the parameters about the rate of turbulent mixing and concentration variance of mixture were established. Moreover, weight analysis of the effect of fuel injection system and combustion chamber structural parameters on indicated power was carried out using orthogonal method.The results show that diesel engine power decreases after increasing with the increase of chamber caliberdepth ratio. When the caliberdepth ratio equals to 6.4, diesel engine is the most powerful, mixing is the most uniform. For different combustion chamber, fuel injection system parameters are of different weights for power. With the combustion chamber caliberdepth ratio increases, the weight of injection pressure decreases, the weight of spray angle of increases, the weight of nozzle number and diameter reduces, the weight of injection timing decreases and then increases.

Analysis of Track-Terrain Interaction on Soft Soil

LI Jun, LI Qiang, ZHOU Jing-kai, ZHANG Yu, XIE Chao-yang

2012, 33(12):  1423-1429.  doi:10.3969/j.issn.1000-1093.2012.12.003

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Under the action of the crawler of the tracked vehicle, the soil compaction produces a displacement.with transverse perturbation so the affected area under the interaction between the track and the soil is 3D. To analyze the trackterrain interaction more entirety and forecast the drawpull, the trackterrain interaction should be analyzed from the view of 3D. At first, MckyesAli 3D model was used to analyze the interaction of the baffle and the terrain, and the similarity of the baffleterrain interaction and trackterrain interaction was discussed. The 3D model was used to analyze the trackterrain interaction. The effectiveness of the 3D model was verified by using the experimental data and choosing the drawbar pull as evaluation criteria. And by comparing the 3D model with Bakker model, the predicted value from the 3D model is closer to the measured value. The study of 3D model provides the reference for the further study of the trackterrain mechanics and also provides a theoretical basis and foundation for the analysis of the interaction between the track and the terrain in the 3D space.

Research on Analysis of Structure Strength in Landing Cushion Process for Airborne Vehicle

HOU Dian-hui, WANG Hong-yan, HAO Gui-xiang

2012, 33(12):  1430-1435.  doi:10.3969/j.issn.1000-1093.2012.12.004

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A finite element model of hull and airbags for landing cushion process was established to research structure strength in landing cushion process of airborne vehicle based on finite element method. On this base, the maximal acceleration results of simulation were given under two conditions and compared to the results of airdrop tests. The simulation results can reproduce the landing cushion process of airborne vehicle exactly.The impact acceleration of hull satisfies requirement of landing cushion process. The stress distribution in normal airdrop condition and worse airdrop condition were obtained through simulation. The results show that the maximal Von Mises stress values of hull don’t exceed tensile strength of the material, and the structure strength fulfils design requirements.

Numerical Simulation of High Density-High Speed Combustion Process in Diesel Engine

YOU Guo-dong, SU Tie-xiong, SUN Li-wei, XU Jun-feng, XU Chun-long, WANG Zeng-quan

2012, 33(12):  1436-1441.  doi:10.3969/j.issn.1000-1093.2012.12.005

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For the combustion progress changes of diesel engine with high specific power，study of submodels for combustion analysis of the high densityhigh speed combustion was carried out by a CFD code Fire. The key parameters of spray breakup model WAVE model and turbulence controlled combustion model eddy breakup (EBU) model were calibrated with experimental results of a single cylinder diesel. The combustion was numerated，with full load condition at constant speed of 3 600 r/min. The simulated result shows that the combustion parameters such as cylinder average pressure，indicated power and heat release rate are in well coincident with the experiment results. The fuel distribution in cylinder is a good condition，the temperature distribution is uniform. The method of CFD modeling is valid to simulate the high densityhigh speed diesel combustion.

Loading Spectrum Simulation and Experiment Study of the Armored Vehicle Engine

LUO Qing-guo, WANG Xu-dong, ZHANG Geng-yun, GONG Zheng-bo, RAN Guang-zheng

2012, 33(12):  1442-1447.  doi:10.3969/j.issn.1000-1093.2012.12.006

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Loading spectrum is the basis of the structure and life research of the armored vehicle engine. The armored vehicle is taken as the subject, based on the working process simulation method of diesel engine, multibody system dynamic theory and cosimulation technology, the power performance simulation model was built including the power unit, driven unit and running unit. The model simulated the influence of the operation of the driver and the transient operation condition of the engine, and designed the gear and vehicle speed sensor, and the model is validated by the experiment. Analyzed the load parameters of the engine, and established the loading spectrum of the engine and its components assembly, the method lays the foundation of the dependability design and experiment for the armored vehicle engine based on loading spectrum.

Multidimensional Simulation for the Effect of Plateau Environment on Combustion Process in Diesel Engine

GAO Rong-gang， LI Guo-xiu， YU Yu-song， LI Hong-meng

2012, 33(12):  1448-1454.  doi:10.3969/j.issn.1000-1093.2012.12.007

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In order to investigate the reasons for the degradation of dynamic performance of diesel engines under plateau environment, multidimensional simulation under different altitudes was conducted to study the combustion process. A set of characteristic parameters accounting for mixing in combustion chamber was established, basing on it, quantitative analysis of the influence of plateau environment on mixing process was conducted. And then the influence of plateau environment on combustion process was investigated mainly by analyzing the heat release rate in the engine. The results show that, under plateau environment, near the wall of combustion chamber easily forms rich mixture, which leads to a reducing of air utilization rate in the center of combustion chamber, a mass of rich mixture still exists at late combustion process. With the rise of altitude, the center area of high temperature moves to the wall of combustion chamber, and causes the deterioration of combustion efficiency. The influence of plateau environment on premixing combustion is not obvious, however, with the rise of altitude, heat release rate of diffusion combustion reduces gradually, and the duration of combustion increases sharply.

CharacteristicBased Numerical Analysis of Transitional Flow in Servocontrolled Hydraulic Piplines

MU Dong-jie, LI Chang-chun, YAN Hao, SUN Meng

2012, 33(12):  1455-1460.  doi:10.3969/j.issn.1000-1093.2012.12.008

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According to the oscillating flow in servocontrolled hydraulic piplines, the actual movement of the transient transition flow was considered. The momentum change of the fluid was analysised in the transient process based on considering its microcompression, and an improved fluid dynamic model of pipeline was proposed. Based on the onedimensional fluid transient theory, the analytical model of fluid transients in hydraulic piplines was carried out by the characteristic method and the finite difference method. The correctness of the simulation was approved by the comparison of calculation data with experiment data .The results show that these models give more reasonable descriptions for water hammer and flow oscillation during servo valve starting process and can provide guidance for designs and experiments of the hydraulic pipe system．

Research on Simulation and Optimization of Cushion Characteristic of Airbags for Airborne Vehicle

WANG Hong-yan, HONG Huang-jie, LI Jian-yang, RUI Qiang, HAO Gui-xiang

2012, 33(12):  1461-1466.  doi:10.3969/j.issn.1000-1093.2012.12.009

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An finite element (FE) model of airborne vehicle and its airbags was established and verified experimentally. The simulation results agree very well with the experimental results, which indicate that the established model is valid for further research. Airbags cushion system and the optimization of the design based on a complex nonlinear model is very difficult by traditional iterative approach method. Thus, equivalent response mode was employed to optimize the parameters of airbags. The optimization result shows that the maximal acceleration of airborne vehicle landing reduces 19.81%, while the energy absorption of airbags increases 7.85%. The performance of the airbags cushion system is largely improved through optimization.

Analysis of Complex Firing Gate Based on Theory of Random Cutthrough

WANG Tian-xiong, LU Ming, PANG Sheng-han, ZHANG Jie, BO Yu-ming

2012, 33(12):  1467-1472.  doi:10.3969/j.issn.1000-1093.2012.12.010

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The timebased distribution of vibration angular velocity of a barrel excited by the road irregularity, etc. and the relationship between it and angular error process of the barrel were analyzed in the context of highspeed gun firing on the move. A method to derive the angular velocity process of barrel was proposed based on mean square derivative, and the random cutthrough characteristics of locationspeed complex firing gate was analyzed. The simulation results show that complex firing gate, compared to simple firing gate, has the better indicators of random cutthrough characteristics.

An Experimental Research on Lowvelocity Projectiles Perforating Fiber and Metal Combined Thin Targets

CHEN Chang-hai, ZHU Xi, HOU Hai-liang, SHEN Xiao-le, TANG Ting

2012, 33(12):  1473-1479.  doi:10.3969/j.issn.1000-1093.2012.12.011

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Lowvelocity ballistic experiments were carried out to study the perforationresistant mechanisms of warship topside composite armor system, which was simulated by composite laminates at the front and homogeneous steel plates at the back. Failure modes and energy absorbing mechanisms were investigated and the influence of the area density of front composite armors on total perforation resistance of combined targets was analyzed. Based on the experiments, an equation was obtained to predict the residual velocities in the case of lowvelocity perforation of combined targets by hemisphericalnosed projectiles according to the failure modes of the targets. The results show that under low velocity perforation, combined targets mainly exhibit local damage. A few amounts of fiber at the impact side of front composite armor are sheared by the projectile. Failure modes of front composite armors are mainly fiber tensile rupture while for steel backing plates, failure modes are primarily petaloid damage. The whole energyabsorbing capability of combined targets increases with increasing the area density of front composite armors. It is shown that theoretical predictions coincide with the experimental results in terms of residual velocities.

Hardware Architecture Design and Analysis of a Fiber Optic Bus Based on the RapidIO Protocol

QIAN Ying-qing， WANG Xiao-feng， LAO Li， XU Run-hua， JIANG Liang-hong

2012, 33(12):  1480-1484.  doi:10.3969/j.issn.1000-1093.2012.12.012

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A fiber optic bus based on the RapidIO protocol was designed. The bus uses a star topology structure. It expanded the shortdistance electrical interconnection between node and switch board into a longdistance fiber optic interconnection through highbandwidth and antijamming fiber channel, and it employed the backplane cascaded method and fiber optic cascaded method to achieve the expansion of the bus node. The paper focused on the hardware architecture design of the node, switch board, and the I/O board. According to the RapidIO protocol，through analyzing the impact of the delay on the transmission performance, it proposed the design method of adopting transmission delay calculation to guarantee the transmission performance, and then calculated the ultimate length of the optical fiber. In the preliminary stage of engineering design, it tested the waveform parameters of serial RapidIO data through fiber optic transmitter and receiver circuit, and verified its performance.

Research on the Key Technology of the Semiconductor Laser Light Source with Highpower and Narrowpulse

XIN De-sheng， ZHANG Jian-jia， CHENG Yong-jie

2012, 33(12):  1485-1492.  doi:10.3969/j.issn.1000-1093.2012.12.013

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For the laser light source with the highpower and narrowpulse, the simple method of the extract parameters of equivalent circuit model was proposed, base on measuring external characteristic，which to solve the problem of the extraction for the equivalent circuit of the laser multichip array structure. The basic features are as follows: without the data of the internal structure and the materials of the semiconductor，measuring the electrical parameters of the real circuit system and using Pspice simulation software to gain multiple sets of data for fitting equivalent circuit parameters of the semiconductor laser. The results are consistent with that given by the foreign products.It provides a foundation for the driver source design of the laser diode with highpower and narrowpulse, and has the guiding significance for the combination,the array structure planing and assembly process of the multichip. On this basis, the driver source circuit experiment system of the semiconductor lasers onboard structure was designed and manufactured, the output power of 180 W, the rise time of the light pulse of 3.2 ns was obtained and the corresponding pulse width was 8.3 ns.

Experiment Investigation on Quasistatic Pressure in Explosion Containment Vessels

WANG Deng-wang, ZHANG De-zhi, LI Yan, WANG Chang-li, LIU Wen-xiang, WANG Hui

2012, 33(12):  1493-1497.  doi:10.3969/j.issn.1000-1093.2012.12.014

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Because of explosion complexities, the investigation on quasistatic pressure after explosion was very scarce. But it was the foundation for safety assessment and failure analysis of explosive containment vessels (ECV). For studying quasistatic pressure in ECV, a reusable ECV of 195 mm in inside diameter and 8.87 kg/m3 in the largest charge density ratio (Q/V) was designed. The static pressure timevarying law and the fitting equation bwtween quasistatic pressure and charge density ratio were obtained experimentally. The results show that there exists a quick increasing—exponential decreasing—rerising—quasistatic process.

Thickness Design of Ferromagnetic Shield for Magnetic Detection

ZHOU Jian-jun， LIN Chun-sheng， HU Ye-qing， HUANG Fan

2012, 33(12):  1498-1503.  doi:10.3969/j.issn.1000-1093.2012.12.015

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The formula of inductive magneticmoment of the ferromagnetic shield was derived for the thickness design of shield used for highprecision magnetic detection. And then the bestthickness of the shield was defined to establish the bestthickness model which is verified by an elaborated experiment. The results show that the magnetic leakage of the magnetic source in the shield decreases with the increase in the thickness which leads to the additional interference. The slope of magnetic leakage decreases, meanwhile the slope of the additional interference increases. The bestthickness model was validated by using the experimental results.

A Parameter Estimation and Filtering Method of Chaotic System Based on Particle Filter

LI Guo-hui, LI Ya-an, YANG Hong

2012, 33(12):  1504-1509.  doi:10.3969/j.issn.1000-1093.2012.12.016

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The parameter estimation of chaotic system is a premise of system control and synchronization. In view of chaotic system's characteristics, such as sensitivity to initial condition, longterm unpredictability and so on, a filter applying to chaotic system was proposed based on chaotic system state space theory and particle filter (PF) theory. In a superimposed noise conditions, the parameter estimation and filtering of Lorenz chaotic system were simulated and analyzed. The simulation results show the proposed filtering algorithm is better than a chaotic system parameter estimation and filtering method based on extended Kalman filter (EKF) in bias estimates, and is an effective method for estimating the parameters of chaotic system and filter.

Study on UAV Offensive/Defensive Game Strategy Based on Uncertain Information

CHEN Xia, LIU Min, HU Yong-xin

2012, 33(12):  1510-1515.  doi:10.3969/j.issn.1000-1093.2012.12.017

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The offensive/defensive problem of unmanned aerial vehicle (UAV) in an uncertain environment was presented by analyzing the uncertain information of target value and damage probability. An offensive/defensive payoff function of UAV in the case of uncertain information was established based on the information value of friend and enemy’s missiles, and the offensive/defensive game payoff matrix was built. The Nash equilibrium of the game was obtained by combining the particle swarm optimization algorithm and the interval number multiple attribute ranking method in the case of uncertain information. A new method for UAV offensive/defensive game to achieve optimal strategy was proposed. Finally the feasibility and effectiveness of the method was verified by simulation.

Study on Compensation Method of Geometric Error for Threeaxis Machining Center

HE Chun-yan, LI Wei-min, ZHANG Jian-jun, HUANG Tian

2012, 33(12):  1516-1520.  doi:10.3969/j.issn.1000-1093.2012.12.018

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To improve the machining accuracy of machine tool, the geometric error compensation for threeaxis vertical machining center was studied through error compensation. Based on the idea of hierarchical compensation, analyzing the feature of the structure of machine tool and using geometric error compensation module in a commercial CNC system (SIEMENS 840D), the geometric errors of the machine center were divided into compensable errors and uncompensable errors and an error model for compensation was established according to the compensable errors. An experiment was carried out in 0540D threeaxis vertical machining center. The results show that the kinematic accuracy after compensation is improved.

Target Identification of Acoustic Signals Based on Multifractal Analysis and Support Vector Machine

DING Kai， FANG Xiang， ZHANG Wei-ping， FAN Lei， LI Xing-hua， XIE Li-jun

2012, 33(12):  1521-1526.  doi:10.3969/j.issn.1000-1093.2012.12.019

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In order to improve the recognition rate of smart landmines for armored target，as the acoustic signals radiated from armored vehicles have been proved to be nonlinear，an identification model based on multifractal analysis and support vector machine(SVM) was established．40 sample signals for each armored target(a certain type of wheeled armored vehicle and a tank) running in different speeds(2 working conditions) were collected by outdoor experiment．The generalized fractal dimension spectrums(GFDS) for both target signals were calculated based on multifractal analysis，and the characters of GFDS under 2 working conditions were analyzed．The GFDS values were input into SVM classification model，and the optimal identification results were obtained by training the model．After an identification effect comparison between GFDS and wavelet packet energy (WPE) method，the results show that the model based on GFDS and SVM has a recognition rate of 92.5%，which is higher than the 85% by WPE method．

Parameter Identification of Servo System for Excavator Arm Based on Hammerstein Model

YAN Jun, LI Bo, GUO Gang, ZENG Yong-hua, PENG Zhuo, ZHANG Mei-jun

2012, 33(12):  1527-1532.  doi:10.3969/j.issn.1000-1093.2012.12.020

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According to the complex nonlinear properties of hydraulic excavator arm’s servo system, a Hammerstein model which contains static nonlinearity and dynamic linearity was adopted to describe the system instead of linear model. The dynamic linear module was described by a discrete AutoRegressive eXogeneous (ARX) model, and the static nonlinearity module was described by a twosegment polynomial. The forgetting factor recursive least square method was applied to realize decomposition identification of the parameters for both linear and nonlinear module through multifrequency sinusoidal input and angle output signal. The comparison experiments between the identified Hammerstein model and ARX model indicated that the error of Hammerstein model was reduced by 77%, the results demonstrated that Hammerstein model meets the need for describing the servo system of excavator arm.

Research Notes

Research and Simulation of the Gravitational Search Algorithms with Immunity

YANG Jing， LI Fang， DI Peng

2012, 33(12):  1533-1538.  doi:10.3969/j.issn.1000-1093.2012.12.021

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Inspired by the immune mechanism of organisms immune system，the local optimize performance of gravitational search algorithm (GSA) was improved by the immune information processing mechanism，and the GSA with immunity was proposed. The proposed algorithms have both the advantages of the original GSA and the immune information processing mechanism of immune system，which can improve the abilities of seeking the global excellent result and evolution speed. The computer simulation result in examples demonstrates that the proposed algorithms are superior to the original GSA.

Optimization of a Novel Magnetic Adsorption Unit for Wallclimbing Robot

CHEN Yong， WANG Chang-ming， BAO Jian-dong

2012, 33(12):  1539-1544.  doi:10.3969/j.issn.1000-1093.2012.12.022

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To satisfy the requirements on loading ability and manoeuvrability of the wallclimbing robot, a novel magnetic adsorption device with variable magnetic force was proposed. First, its configuration was introduced and threedimensional magnetic field models were established, then the magnetic field of novel magnetic adsorption unit based on finite element method was analyzed, and its magnetic flux density distribution and magnetic adsorption force were obtained. The APDL parametric technology of ANSYS was used to optimize the dimensions of magnetic unit, and optimization principle was obtained by analysis. By simulation and comparison of performance parameters of traditional Hshaped magnetic adsorption device, it is shown that the novel one has the characteristics of high utilization of permanent magnet, large ratio of the maximum and minimum adsorption force, light weight and strong loading ability. The result is proved by experiment and provides the basis for the design of wallclimbing robot magnetic adsorption device.

Study on Effect of Peroxide Properties for Biodiesel and Emissions

LI Rui-na， WANG Zhong， LI Ming-di， XU Guang-ju, MAO Gong-ping， WANG Xiao-zhe

2012, 33(12):  1545-1548.  doi:10.3969/j.issn.1000-1093.2012.12.023

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Biodiesel was redesigned by peroxidation. The mechanism of peroxide modification was discussed. The viscosity and peroxide value of biodiesel before and after peroxide modifications were measured and analyzed. Experiments were carried out in a 170F engine fueled with biodiesel and peroxide biodiesel, and the impacts of peroxide modification on NOx emissions and carbon smoke were studied. The results show that the carbon double bonds of fatty acid methyl esters are broken after peroxide modification, the degree of saturation is increased, oxidation stability is improved significantly, and dynamic viscosity of biodiesel is much lower than that of biodiesel up to a maximum of 8.2%. Both NOx emission and carbon smoke decrease for the investigated operating conditions.

Status and Development of Protection Technology of Armored Vehicles

CAO He-quan， ZHANG Guang-ming， SUN Su-jie， SUN Bao-sen

2012, 33(12):  1549-1554.  doi:10.3969/j.issn.1000-1093.2012.12.024

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In order to improve the survival ability of armored vehicles in the war, the protecting technology has been attached importance and developed completely by the world military powers. The paper presented the research state and protecting level of modern armor, and enumerated protecting furnishment of advanced armored vehicles, and summarized the research state and level of key protecting technologyarmor material. After introducing situation of armor protecting technology, taking the research content of U.S. and U.K., the development trend to the modern armor technologysynthesis protection system were analyzed.