Table of Content

31 August 2015, Volume 36 Issue 8

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Paper

Shift Sequence Optimization of Heavy-duty Vehicles with Automated Manual Transmission

LIU Hai-ou, JIN Lei, DONG Shi-jin, MIAO Cheng-sheng

2015, 36(8):  1377-1383.  doi:10.3969/j.issn.1000-1093.2015.08.001

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Heavy-duty vehicles have larger space to promote both in dynamic performance and fuel economy. A dynamic model of heavy-duty vehicle equipped with automated manual transmission (AMT) is built based on the analysis of gearshift power interruption. A dynamic programming (DP) method is applied to solve the optimal gearshift sequence in known road condition. The performance comparison between original shift sche-dule and DP strategy is completed. The simulation results show that the optimal gearshift sequence provides good overall performance, including dynamics and fuel economy, by adjusting the fuel consumption and travel time weighting factor. In addition, the optimal gearshift sequence from DP strategy improves the fuel economy in ensuring the dynamics.

Research on Effect of Late Intake Valve Closing Miller Cycle on Combustion and Emissions of Diesel Engine

WEI Sheng-li， LIU Xin， LENG Xian-yin， LIANG Yu， JI Kun-peng， WANG Fei-hu

2015, 36(8):  1384-1390.  doi:10.3969/j.issn.1000-1093.2015.08.002

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The effect of late intake valve closing (LIVC) Miller cycle on combustion and emissions of D6114 diesel engine is analyzed based on a BOOST model. The results show that the closing time of intake valve can be delayed to decrease the compression pressure and the temperature, thus increasing the ignition delay period. Due to lacking of oxygen, the average in-cylinder temperature and soot emission increase. The boost ratio can be enhanced to compensate the loss of intake. It is also found that the late closing of LIVC, in conjunction with the increase in boost pressure and the delay of injecting time, can simultaneously reduce NO_x and soot emission. When the peak pressure is the same as that in the original engine, the fuel consumption is 4 g/(kW·h) lower than that the original engine, the soot emissions are reduced by 6%, and NO_x emissions are reduced by 31% by using the scheme of M60 and 2°CA of injecting time.

Design of Sliding Mode Controller for All-wheel Steering System of Three-axle Vehicle

YUAN Lei， LIU Wei-ping， LIU Xi-xia

2015, 36(8):  1391-1397.  doi:10.3969/j.issn.1000-1093.2015.08.003

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For further research on the dynamic behavior of three-axle vehicle with all-wheel steering system, an all-wheel steering vehicle dynamic model is built considering the nonliner characteristics and load changes of wheels. To improve the handling stability of three-axle vehicle with all-wheel steering system, an all-wheel steering controller is designed based on the siding mode variable structure control theory, which can follow a reference model that contains an ideal yaw rate of the double-front-axle steering vehicle and the zero side-slip model. The double-front-axle steering vehicle, the all-wheel steering vehicle with zero side-slip angle proportional controller and the all-wheel steering vehicle with sliding mode controller are compared under different conditions. The result shows that the siding mode controller can ensure the smaller slide-slip angle and the ideal yaw rate, which can resist the interference from lateral wind and road conditions.

Rigid-flexible Coupling Dynamic Modeling and Error Analysis of Loading Mechanism of Naval Gun Based on MetamorphicPrinciple

HU Sheng-hai, GUO Chun-yang, YU Wei, QI Song, SUN Jun-chao

2015, 36(8):  1398-1404.  doi:10.3969/j.issn.1000-1093.2015.08.004

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In order to meet the development needs of large caliber naval gun, a loading mechanism based on the metamorphic principle is proposed. The structure of loading mechanism is designed by using the metamorphic principle, and the motion description and principle analysis of the structure are conducted by combining the kinematic diagram of mechanism. The flexible rod is divided into some beam elements by using finite element discrete method, the deformation of beam elements is descripted under the mixed coordinate system, and a dynamic equation of the flexible rod is presented. A rigid-flexible dynamic equation is established by using Hamilton variational principle. The simulation result is gotten through the combined simulation of Adams and Ansys. The result shows that a big ammo-feeding error exists in the loading mechanism based on the metamorphic principle when the system moves in a large range at a high-speed. The influence of the flexible deformation of rod on loading accuracy should be considered in the research of large caliber naval gun based on the metamorphic principle.

Asymptotic Tracking Control of Motor Servo System with Input Constraint

DONG Zhen-le, YAO Jian-yong, MA Da-wei

2015, 36(8):  1405-1410.  doi:10.3969/j.issn.1000-1093.2015.08.005

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Parameter uncertainties, uncertain nonlinearities (especially the nonlinear frictions) and input constraint are the common problems existing in motor servo systems. For the above problems, a new method, based on the robust integral of the sign of error (RISE) design, is proposed to achieve the asymptotic tracking performance in the presence of parameter uncertainties, uncertain nonlinearities and input constraint. The stability of asymptotic tracking is proved via the Lyapunov analysis. Simulation results illustrate that the proposed approach can be used to achieve the excellent response speed and tracking performance under input constraint, and has a strong robustness.

Analysis of Inflation and Aerodynamic Characteristics of Vortex Ring Parachute

MA Xiao-dong, GUO Rui, LIU Rong-zhong, LYU Sheng-tao

2015, 36(8):  1411-1416.  doi:10.3969/j.issn.1000-1093.2015.08.006

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To explore the inflation performance and aerodynamic characteristics of vortex ring parachute which is often used as decelerating and spinning parachute of smart ammunition, the inflation process under the conditions of infinite mass and slow flow velocity is simulated using arbitrary Lagrange-Euler method. The canopy deforming process, time-history curves of spinning rate and projected diameter and fluid domain features at steady state are obtained. The finite model of inflated canopies is transformed to a simulation model of aerodynamic characteristics. The aerodynamic force parameters, the features of velocity streamlines and the pressure distribution are obtained by using computational fluid dynamics method. The results obtained by the two methods are compared and analyzed. The results show that the vortex ring parachute can inflate smoothly and rotateat 12 m/s. The shape of inflated canopy is plump and the steady spinning rate is about 3.3 r/s. The drag coefficient is about 1.36, which is greater than those of other typical parachutes with axial symmetry structure. The spinning moment coefficient is 0.87. The distributions of fluid domain features are centrally symmetrical around the parachute axis.

The Energy Conversion and Fragment Initial Velocity Model of Metal Cylinder Driven by Detonation

WANG Xin-ying, WANG Shu-shan, XU Yu-xin, HU Sai

2015, 36(8):  1417-1422.  doi:10.3969/j.issn.1000-1093.2015.08.007

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Based on the JWL equation of state of detonation products and Taylor fracture criteria, a model considered the expansion details about energy conversion and fragment initial velocity is derived from conversation of energy. The cylinder tests of three materials, including copper, 45^# steel and 6061 aluminum alloy, driven by TNT explosive are made, and the inflation track and velocity are analyzed. The experimental results show that, by comparing with Gurney formula which is considered only to express the driving ability of the explosion parameter, the proposed model considers the driving factors, inflation process and mechanics function of meta. The result is of pertinence and applicability.

Research on Combustion Performance of Small-bore Molded Combustible Cartridge Case and Charge

ZOU Wei-wei, HAO Xiao-qin, ZHANG Zhi-yong, DANG Hai-yan, ZHOU Wei-liang

2015, 36(8):  1423-1429.  doi:10.3969/j.issn.1000-1093.2015.08.008

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In order to improve the burning-off property, a small-bore combustible cartridge cases with energetic fibers are manufactured by using pulp molding method. The combustion performance and mechani-cal property of small-bore combustible cartridge case and the energy discharge function of combustible small-bore cartridge case charge are analyzed by experimental measurement. The results show that the small-bore combustible cartridge case with energetic fibers is beneficial to increase the burning rate, shorten the constant volume combustion time, and improve the burn-off property and ballistic property. The impetus of the mixed charge declines and burning rate increases with the increase in CCC . Compared to the mixed charge of combustible cartridge case and 4/7 single base propellants, the small-bore combustible cartridge case with 7/19 single base propellants is more reasonable, the charge energy decline lightly and the energy can be released sufficiently.

PreparationPerformance and Long-term Storage of Nano Al/Bi₂O₃

HUANG Fan-tai, ZHANG Lin, ZHU Shun-guan

2015, 36(8):  1430-1436.  doi:10.3969/j.issn.1000-1093.2015.08.009

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Nanoparticle bismuth oxide is prepared by a solution method, and then Al/Bi₂O₃ is self-assembled using P4VP. The samples are characterized by XRD, SEM, DSC, and P-t curve. The reaction time of self-assembled Al/Bi₂O₃ is 0.036 s, the maximum pressure is 4 729 kPa, and the time corresponding to the pressure peak is 0.162 s. The results show that Al/Bi₂O₃ has the advantage of rapid reaction over Al/Fe₂O₃ and Al/CuO. After accelerated aging test, aluminium powder and bismuth oxide powder contact with each other more closely without obvious agglomeration. After aging, it is equivalent to store for 15 years at room temperature, the oxide layer thickness of aluminium powder is increased from 3.2 nm to 4.6 nm, Al/Bi₂O₃ heat release is gradually reduced from 1 112 J/g to 606 J/g, the ignition time of semiconductor bridge is increased from 37.20 ms to 50.88 ms, and the ignition energy is increased from 0.64 mJ to 1.17 mJ.

In-line Rheological Behaviors and Numerical Simulation of Material in Extrusion Processing

DING Ya-jun, YING San-jiu

2015, 36(8):  1437-1442.  doi:10.3969/j.issn.1000-1093.2015.08.010

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The die rheometer is utilized to investigate the in-line rheological behaviors of CDA solution, as the substitute of NC, in extrusion processing. The experimental results demonstrate that CDA solution is a non-Newtonian pseudoplastic fluid, and the increase in processing temperature is in favor of improving the rheological behaviors of CDA solution. The finite element software Polyflow is provided for the numerical simulation of CDA solution in the die to get the distribution of pressure, shear rate and shear viscosity. A power model is applied as the constitutive equation. The data calculated by the numerical simulation is close to the results obtained from the experiment. Polyflow indicates that the higher screw speed not only decreases the viscosity but also increases the pressure and pressure drop rate which is disadvantageous to the quality and processing security of propellants. The experiment and numerical simulation of the in-line rheological behaviors of CDA solution have the guiding significance for the continuous processing of gun propellants.

A Novel Sliding Mode Guidance Law with Impact Angle Constraint for Maneuvering Target Interception

ZHANG Yao, GUO Jie, TANG Sheng-jing, SHANG Wei, ZHANG Hao-qiang

2015, 36(8):  1443-1457.  doi:10.3969/j.issn.1000-1093.2015.08.011

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A novel missile sliding mode guidance law (SMGL) in which a missile intercepts maneuvering target is proposed, which is based on a combination of the advantages of integral sliding mode control and global sliding mode control. The relative motion equations of missile and target, in which the impact angle constraints are considered, are established within the perpendicular plane. A new nonlinear saturation function is adopted to construct an integral term in global integral sliding mode surface, and then an improved nonlinear global integral sliding mode control technique is presented, which solves the problem about system transient performance deterioration and decreases the steady state errors. It is obvious that the designed guidance law enables the missile to hit target at a desirable impact angle in finite time, and the missile to be of strong robustness during the whole interception. The missile global nonlinear integral SMGL in which the autopilot dynamics and impact angle constraints are considered is investigated by adopting dynamic surface control. It is demonstrated that all states in the closed loop system are ultimately bounded on the account of Lyapunov stability theorem. The simulation results verify the effectiveness and superiority of global nonlinear integral SMGL.

Omni-bearing Fast Pre-orientation of Pendulous Gyroscope Based on Period-amplitude Measuring

CHEN He, ZHANG Zhi-li, ZHOU Zhao-fa, ZHAO Xiao-feng

2015, 36(8):  1458-1465.  doi:10.3969/j.issn.1000-1093.2015.08.012

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A novel omni-bearing pre-orientation method based on period-amplitude measuring is put forward through the analysis of motion characteristics of pendulous gyro north seeker in wide azimuth. The proposed method can be used to calculate the azimuth of the gyro shaft by measuring its swing period and amplitude. The effect of gyro-motor rotating rate on pre-orientation time is analyzed, the effect of pertinent parameter errors on pre-orientation accuracy is discussed, and the preliminary experiments are conducted to verify the new method. Both the theoretical and experimental results show that the swing period can be shortened by decreasing the rotating speed of the gyro-rotor, and the rapid pre-orientation can be achieved accordingly within 65 s with the accuracy of higher than 5°, which can meet the accuracy requirement of subsequent north seeking procedures.

ULS-SVM Prediction Model of Missile Guidance and Control Systems Based on D-S Evidence Theory

CONG Lin-hu， XU Ting-xue， GOU Kai

2015, 36(8):  1466-1472.  doi:10.3969/j.issn.1000-1093.2015.08.013

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For intense electronic equipment in missile guidance and control systems, coupling relationship among feature parameters and low prediction accuracy of traditional least squares support vector machine（LS-SVM），the traditional LS-SVM is improved by analyzing the temporal correlation and spatial correlation of feature parameters. Traditional LS-SVM and improved LS-SVM are fused by taking advantage of D-S evidence theory. An unification of least squares support vector machine（ULS-SVM）prediction model is established. The key parameters are predicted by taking missile guidance and control systems as an example. The results show that the proposed ULS-SVM prediction model is rational and effective.

Research on Guidance Matching of Guidance Law with Multiple Constraints and Seeker Disturbance Rejection Rate

ZHANG Wen-yuan, XIA Qun-li, LIU Da-wei

2015, 36(8):  1473-1480.  doi:10.3969/j.issn.1000-1093.2015.08.014

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A guidance law with multiple constraints (GLMC) is derived in light of the effect of disturbance rejection rate of seeker on the stability and guidance accuracy of the multi-constraint guidance system, and a multi-constraint guidance model is established, in which the disturbance rejection rate of seeker is considered. The effect of disturbance rejection rate and guidance parameters on the stability of guidance system is analyzed. In addition, the adjoint function is employed to analyze the guidance performance variations of the multi-constraint guidance law with or without the influence of disturbance rejection rate of seeker. The results indicate that any decrease in guidance time constant or flight remaining time as well as increase in the disturbance rejection rate will lead to a decrease in the stability of guidance system. The GLMC can sustain a disturbance rejection rate of about 1%. In the practical applications, it is essential to control the level of disturbance rejection rate of seeker strictly and reduce the effect of parasitical loop on the stability of guidance system so that a superior guidance performance of the multi-constraint guidance law can be ensured.

Study of High Precision Zero Point Momentum Detection Technology for White and Shimmer Light Sight

WANG Ying, WANG Jin-song, CUI Shi-bao, AN Zhi-yong

2015, 36(8):  1481-1486.  doi:10.3969/j.issn.1000-1093.2015.08.015

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For the requirements of the sight line alteration detection of the combined sight adding a shimmer lens group to the white sight, a high-precision measurement method can be used to measure the true sight line alteration of combined sight as well as the optic axis variation of shimmer lens group. In the method, a CCD camera is used to measure the total sight line alteration，and the errors caused by assembling the combined sight and the attitude change of adjusting bracket caused by assembling the shimmer lens group are quantitatively measured using a dual-auto-collimator, which are eliminated from the measured values to get a true sight line alteration. A theoretical detection model is presented, and the measuring experiment is made. The results show that the measured value of sight line alteration σ is less than 2.16″(0.01 mil); the measured value of the optic axis variation of shimmer lens group σ is less than 21.6″(0.1 mil).

Multitarget Angle Estimation for Bistatic MIMO Radar under the Missmatch of Matching Filter

HUANG Zhong-rui, ZHANG Jian-yun, ZHOU Qing-song, NIU Zhao-yang

2015, 36(8):  1487-1493.  doi:10.3969/j.issn.1000-1093.2015.08.016

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A new method for multitarget angle estimation for bistatic multiple-input multiple-output (MIMO) radar based on mismatch filter is proposed. A signal model is built for delay and Doppler frequency offset errors of bistatic MIMO radar. The parameter estimation of direction of departure (DOD), delay errors and Doppler frequency offset errors is converted into a quadratic programing (QP) problem and solved via the alternating iterative algorithm, and then the DOD can be estimated. The direction of arrival (DOA) is estimated via ESPRIT algorithm. The automatic pairing of DODs and DOAs can be realized without pairing algorithm. The efficiency of the proposed method is verified through the computer simulation. The Cramer-Rao bound (CRB) of the proposed MIMO radar signal model is derived in the appendix.

Feature Extraction Method for Tolerance Circuit Fault Diagnosis Based on Improved Basic Particle Swarm OptimizationAlgorithm

LIU Hong, CAO Ying, LONG Teng-wu

2015, 36(8):  1494-1501.  doi:10.3969/j.issn.1000-1093.2015.08.017

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The fault information entropy is used to describe the fault symptoms of output signal of tolerance circuit. Three different feature subset selection rules are adopted, such as equal interval-selected feature point, and feature points selected by maximum information entropy of single feature points and joint information entropy of multiple feature points. Four kinds of improved basic particle swarm optimization (BPSO) algorithms are proposed to search the fault feature subsets. These four algorithms are improved mapping function BPSO algorithm, adaptive weighting BPSO algorithm, natural selection-based BPSO algorithm, and BPSO algorithm based on natural selection and adaptive weighting. The optimal feature subsets obtained by feature extraction are used to train the neural networks as classifier. The fault location of tolerance circuit is completed using a trained neural network . Experimental results show that the optimal feature subset searching methods based on improved BPSO algorithm are valid, and the accuracy of fault location can reach 95.2%.

DNA Genetic Bat Algorithm Based Fractionally Spaced Multi-modulus Algorithm

GUO Ye-cai, WU Hua-peng, WANG Hui, ZHANG Miao-qing

2015, 36(8):  1502-1507.  doi:10.3969/j.issn.1000-1093.2015.08.018

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For the low convergence speed and large mean square error (MSE) of the existing multi-modulus algorithms(MMAs), a DNA genetic bat algorithm based fractionally spaced multi-modulus algorithm(DNA-GBA-FS-MMA) is proposed. In this proposed algorithm, the fractionally spaced equalizer is used to get more detail channel information via oversampling signals. DNA genetic algorithm is introduced into bat algorithm to obtain a new intelligent optimization algorithm, called as DNA genetic bat algorithm (DNA-GBA), and DNA-GBA is used to find the global optimal position vector of the bat swarm serving as the real and imaginary parts of the initial weight vector of multi-modulus algorithm. Simulation results show that DNA-GBA-FS-MMA has the smallest MSE, the fastest convergence speed, and the clearest and most compact constellation points in comparison with the existing multi-modulus algorithms(MMAs).

The Optimization of Assembled Turntable Working Teeth Cathode Profile with Riblet Surface

JIA Jian-li, LIU Jin-he, SHEN Jian-qiang

2015, 36(8):  1508-1517.  doi:10.3969/j.issn.1000-1093.2015.08.019

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The relation between shape parameter and drag reduction of the riblet surface is discussed to optimize the teeth profile of assembled turntable working teeth cathode (TWTC). According to the linear distributing law to which the flow velocity in viscous sublayer of turbulence boundary layer submits, the characteristic parameters of flow field are calculated by the formula of flow velocity in viscous sublayer, and then a scheme of using the riblet surface and transition fillets for working-teeth is investigated. The flow field in the machining gap of the un-optimized TWTC with riblet surface and transition fillets is verified by simulation and experiments. The results show that the assembled TWTC with riblet surface greatly reduces the resistance of electrolyte flow channel and increases the maximum flow velocity of electrolyte in the machining gap from 42.5 m/s to 58.6 m/s. Meanwhile, it boosts anodic dissolution rate as well as material removal rate of electrochemical machining. The cavitations, eddy flow, separation and bubble can be decreased and even avoided using the transition fillets between working teeth, which realize the stable machining of internal spiral line in the uniformed gap and improve the machining accuracy and surface quality of electrochemical machining.

Analysis of Surface Texture of Push-processed Si₃N₄ Ceramics Based on Gray Level Co-occurrence Matrix and Neural Network

TIAN Xin-li, WANG Long, WANG Wang-long, TANG Xiu-jian, WU Zhi-yuan

2015, 36(8):  1518-1524.  doi:10.3969/j.issn.1000-1093.2015.08.020

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Soft push processing based on the edge broken effect to drive crack is a novel processing technique. The surface texture of machined Si₃N₄ ceramic is collected, and the gray level co-occurrence matrix (GLCM) is used to analyze the relationship among contrast, entropy, correlation and machined surface texture. The radial basic network and competitive network are employed to predict and classify the texture characteristics in different processing parameters. The relative error value of the predicted results can be controlled within 5%. The larger the contrast and entropy are, the smaller the correlation is, and the greater the classification level is, the worse the surface roughness is. The processing quality is analyzed by exploring the effects of different process parameters on texture feature. With the increase in feed rate or groove depth, the machined surface quality is worse. With the increase in flange thickness, the machined surface quality is gradually poor. The machined surface quality can be improved when flange thickness is over 2.5 mm boundary point.

UXO Detection Based on Terminal Ballistics Acoustic Signal Analysis of Aerodynamic Noise and Landing Sound

ZHANG Ya-hui, WANG Yu-long, LIU Hao-ting, LI Hong-kai, ZHU Wang-fei, YU Qin-lan

2015, 36(8):  1525-1532.  doi:10.3969/j.issn.1000-1093.2015.08.021

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For the location problem of unexploded ordnance (UXO) in the processes of conventional weapon test, military training and exercises, a low cost UXO detection method of the terminal ballistics is presented. According to the size of the impact area , many low cost acoustic sensors are installed in shooting range. The measuring range of these sensors covers the whole impact area. As for the signals of aerodynamic noise and the landing sound, which are captured by each acoustic sensor, the computation is implemented to used FFT and Laplace wavelet to denoise and enhance the original acoustic signal; use the short time energy, short time amplitude, and short time zero-crossing rate to detect the endpoint of these signals above; use the wavelet packet to collect the features of the enhanced signal; and use the minimized distance-based threshold criterion to identify the aerodynamic noise and the landing sound. The test results of UXO location in the shooting range show that the proposed technique can be used for UXO location and the location accuracy can reach 10 m.

Improved Decomposition-Based Evolutionary Algorithm for Multi-objective Optimization Model of Dynamic Weapon-targetAssignment

ZHANG Ying, YANG Ren-nong, ZUO Jia-liang, JING Xiao-ning, HE Gui-bo

2015, 36(8):  1533-1540.  doi:10.3969/j.issn.1000-1093.2015.08.022

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A reasonable weapon-target assignment(WTA) scheme is developed to optimize the allocation of limited resources, which brings the maximum awards with minimum costs. A dynamic weapon-target assignment(DWTA) multi-objective optimization model is established, especially for the offensive operation with multi-weapon. The proposed model is composed of several stage static models. The parameters of each stage model are obtained from the battlefield in real time. An algorithm is elaborately studied to solve the stage model based on the hypothesis to deal with the dynamic model. According to the characteristic of the proposed model, an encoding mode is constructed to satisfy the resource constraints. An improved decomposition-based evolutionary algorithm is proposed by mixing of tabu search and crowding distance strategies. Comparative experiments prove that the proposed algorithm is feasible, fast and efficient.

Configuration Method of Aiming Points for Future Airspace Window

LU Fa-xing, JIA Zheng-rong, WU Ling, YU Xu-tong

2015, 36(8):  1541-1545.  doi:10.3969/j.issn.1000-1093.2015.08.023

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The theoretical optimal firing density of future airspace window (FAW) is derived. A mesh configuration method of multi- aiming points for FAW, the implement condition and the kill probability formula are presented based on the principle of that the hitting error variance of practical firing density equals to that of the theoretical firing density. The simulation example shows that the kill probability of mesh aiming points approaches the theoretical upper bound of kill probability of FAW, which demonstrates the advantage of the configuration method.

Comprehensive Review

Five Scientific and Technological Problems on Running System of High Mobility Tracked Vehicle

MAO Ming， ZHANG Ya-feng， DU Fu， CHEN Yi-jie

2015, 36(8):  1546-1555.  doi:10.3969/j.issn.1000-1093.2015.08.024

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The running system is very important for tank and armored vehicles, especially for the mobility performance. The running system becomes a bottleneck to improve the performance of tank and armored vehicles due to the complex and adverse working environment. The concept, connotation, research objectives, research contents and research achievements of five scientific and technological problems, such as vibration damping network design based on the electrical and mechanical analogy, nonlinear vibration dynamics of complex system, energy dissipation, ground mechanics and nonlinear vibration control, are discussed. The fundamental theoretical research is carried out, and the key technical problems are overcome by collaborative research.

Research Notes

The Performance Simulation and Experiment of Air Filter of Armored Vehicle in Plateau Environment

LU Jin-jun, LI Ji-Xin, SUN Yang, CHEN Ke-xin, QIAO Meng-hua, LI Wen-chao

2015, 36(8):  1556-1561.  doi:10.3969/j.issn.1000-1093.2015.08.025

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Plateau environment is peculiar, such as high altitude, low temperature, and low atmospheric pressure. The air filters for the traditional heavy armored vehicles are designed according to the atmospheric environment and air density of plain area. In order to ensure that a product meets the use requirements in plateau environment, the working performance of air filter must be predicted. An air filter virtual prototype model of a heavy engineering vehicle is established based on computational fluid dynamics algorithm. The model is optimized to predict the performance of air filter in a different environment. The system performance test of air filter is conducted based on the theoretical research conclusions. The test and simulation results show that the predicted result of virtual model has good consistency with the experimental conclusion.

Analysis about Steering Slip Power Ratio of a Tracked Omnidirectional Mobile Platform

ZHANG Yu-nan, HUANG Tao, ZHANG Shu-yang, ZHANG Jie

2015, 36(8):  1562-1568.  doi:10.3969/j.issn.1000-1093.2015.08.026

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For the limitations of the existing omnidirectional mobile platforms in engineering applications, an omnidirectional track is proposed based on the structure principles of the Mecanum wheel and conventional tracked running mechanisms, and the layout structure of the tracked omnidirectional mobile platform is described. A new concept of steering slip power ratio is proposed by comparing the power consumption of steering sliding resistance of the tracked omnidirectional mobile platform with that of conventional tracked mobile platform because of inevitable slippage between the omnidirectional track and ground in steering motion. And the slip power ratio of steering motion at center point is analyzed. A prototype equipped with an independent electric driving system is developed. When the rollers are locked, the prototype is equivalent to an conventional tracked mobile platform, so the total power consumption of steering motion at center point, which is the total output current of the battery, is measured at the highest and uniform speed in the conditions of free rollers and locked rollers. The results show that the total power consumption of the prototype with free rollers is approximately 53% less than that of the prototype with locked rollers in the center-steering motion.

Theoretical and Experimental Study on the Influence of Ammunition on Firing Accuracy of 5.8mm Rifle

LIU Jia, MA Zhong-liang，DAI Shu-lan，XIAO Zhong-liang, CHENG Shan

2015, 36(8):  1569-1573.  doi:10.3969/j.issn.1000-1093.2015.08.027

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The theoretical formula for calculating the internal ballistic correction coefficients is deduced using interior ballistics equations and derivative operation. The correction coefficients of charge weight, propellant web size and projectile mass are calculated for 5.8 mm rifle. The results show that the influences of the factors on the initial velocity and maximum bore pressure of 5.8 mm rifle are the charge weight, propellant web side and projectile mass in order. The charge weight can be controlled accurately, so only the significant effects of propellant’s size and projectile mass on the velocity of 5.8 mm rifle are analyzed by statistical analysis. The analysis result shows that the propellant’s size is more sensitive to velocity compared with projectile mass, which is in accord with the theoretical calculation. It is an effective way to increase the firing accuracy of 5.8 mm rifle by improving the deviation of propellant’s size.

A Design Method for Multilayered Microwave Absorbing Coating Structure Based on NSGA-Ⅱ

CAI Yun-xiang, ZHOU Zhi-yong, XU Xiao-qian, BI Dao-kun

2015, 36(8):  1574-1579.  doi:10.3969/j.issn.1000-1093.2015.08.028

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The design of coating structure is an important method to achieve the favorable absorbing capability. For the issues in the computer-aided design of cpating structure, such as low operation efficiency, optimization of single target and manual intervention, a multi-objective optimization model of radar absorbing coating with the aim of “thin-layer, light-weight, broad-band and strong-absorbing” is constructed, and an optimized project based on NSGA-Ⅱis presented.The optimized thickness of the double-layer absorbing coating composing of 3^# and 2^# materials is 0.6 mm with the reflectance of lower than -8 dB at 18~18 GHz band. Experiments show that this method can be used for the structure design of multilayered radar absorbing coating in case of prediction of redundancy.

Evaluation Model of Aging Properties of Stealth Coatings Based on Genetic BP Neural Network

LU Yan-li， MU Jing-yang

2015, 36(8):  1580-1586.  doi:10.3969/j.issn.1000-1093.2015.08.029

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In order to research the relationship between the physical values of coating aging in the natural environment and the environmental factors , a genetic BP neural network with real coding, arithmetic crossover, Gauss mutation and climbing operation is designed. The physical values of coating are calculated according to the environmental factors. Visual Studio 2008 is used for programming, and a program is developed for neural network training and prediction program. Finally, an example of field aging data of coating is used for network training and prediction. The results show that the proposed model can be used to calculate the ultimate life of the coating. The calculated values are similar to the measured values. The genetic neural network model can be used for prediction of coating life.

Structure Improvement of Roll-beating Head for Continuous Indexing Cold Roll-beating Machine

MA Qun, LI Yan, YANG Ming-shun, YUAN Qi-long, LI Yu-xi

2015, 36(8):  1587-1593.  doi:10.3969/j.issn.1000-1093.2015.08.030

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Movement interference between roller and workpiece appears during continuous indexing cold roll-beating of involute spline. The rotary shaft of roller can be tilted at a setting-angle to reduce the interference. The forming profile of roller changes to cause new forming errors under the action of setting-angle. The principle of interference is analyzed, and the improved structure of roll-beating head is designed. The roller is inclined in the opposite direction at a setting-angle by an inclined copper bearing, which ensures the forming profile of roller. A mathematic model is established for calculating the forming profile curves of roller on the keyway section , and the forming errors are characterized by keyway width errors. The forming errors are still large when the existing structure of roll-beating head is used, although the forming accuracy is improved under the action of setting-angle. The interference and the forming errors brought by the inclination of roll-beating head are eliminated in a suitable range of setting-angles when the improved structure of roll-beating head is used. The roll-beating head is improved for cold roll-beating experiment. The keyway profiles of samples are precisely measured. The result indicates that the measured values of keyway width errors are consistent with the theoretical values without the action of setting-angle, and the measured values of keyway width errors and their relative variations are both very small under the action of setting-angle.

Investigation of the Tooth Profile Error Based on the Forming Theory of Balloscrew Manufactured by Cold Rolling

LI Yu-xi, LI Yan, YANG Ming-shun, CUI Feng-kui, HE Xuan-jing

2015, 36(8):  1594-1600.  doi:10.3969/j.issn.1000-1093.2015.08.031

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The traditional material removal machining method of ballscrews was broken by cold roll-beating. The cold roll-beating method has the advantages of high efficiency, energy conservation and saving in material. The products processed by the proposed method have high wear resistance and long service life. According to differential geometry and meshing theory, the meshing model and theoretical error model are constructed for the cold roll-beating of ballscrews, and the function of contact line is provided for meshing surface. The relative movement between roller and workpiece is revealed by analyzing the meshing model and the contact line. The profile errors of the gear tooth and the actual helix of the center track of ball are investigated by theoretical calculation and simulation, the causes of errors are analyzed, and the corresponding solutions are given. A self-developed cold roll-beating experimental device is used for cold roll-beating experiment of lead screws. The experimental results show that the actual machining contour line overlaps with the theoretical contact line.