Table of Content

30 August 2014, Volume 35 Issue 8

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Paper

Research on Energy Loss of Fuze Setting System Based on Magnetic Resonant Coupling in Complex Environment

LI Chang-sheng, LI Wei-xin, ZHANG He, DING Li-bo

2014, 35(8):  1137-1143.  doi:10.3969/j.issn.1000-1093.2014.08.001

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In order to solve the problem of that magnetic resonant coupling setting system can not work effectively in complex ferromagnetic environment, an analytical expression of eddy current losses of magnetic resonant coupling setting system is derived based on the basic theory of the electromagnetic quasi-static field, and the influence factors of the energy transmission system are analyzed. Numerical simulation and experiment study are conducted on the fuze setting system in different environments. The results show that theoretical analysis results are consistent with the numerical calculation and experimental results. The system is not working properly mainly due to eddy current loss, which is related to the resonant frequency of the system, and the permeability and conductivity of dielectric material. When ferrite bead is added in slot gap of steel media, the fuze setting system can work effectively after 20 ms, and can meet the requirement. The conclusion on magnetic resonant coupling setting system is helpful to engineering design in complex environment.

Design Method of Magnetic Circuit in Planar Permanent Magnetic Miro-generator

ZHAO Jing-jing, SHI Geng-chen, DU Lin

2014, 35(8):  1144-1151.  doi:10.3969/j.issn.1000-1093.2014.08.002

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A design method of magnetic circuit in a disk-type permanent magnetic micro-generator is proposed, including modeling, theoretical analysis, simulation and experiment. The effects of the structural parameters on magnetic flux density in the magnetic gap and the constraint relations among the parameters are discussed. The calculation method of magnetic flux density in magnetic gap and the optimization scheme of structural parameters of micro-generator are studied. The design method of magnetic circuit in the planar permanent magnetic micro-generator is summarized. Errors between the theoretical calculations and experimental results are less than 7%, which verifies the rationality and accuracy of the calculation method of magnetic flux density.

Analysis of Influence Factors of Projectile Band Bayonet-Chamber Process

LI Miao， QIAN Lin-fang， CHEN Long-miao， XU Ya-dong

2014, 35(8):  1152-1157.  doi:10.3969/j.issn.1000-1093.2014.08.003

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The process of projectile band bayonet-chamber of a new type 155mm howitzer is analyzed to investigate the effect of band bayonet-process parameters on the initial conditions of motion of projectile in bore, and the effects of changes in various parameters of band bayonet-process are presented, such as projectile velocity, frictional coefficient, quadrant angle, initial deflection and barrel-projectile gap. The results are obtained based on the dynamic explicit finite element method. Thus, the factors that influence the bayonet-chamber depth, band-barrel reaction force and bayonet-chamber posture are shown. Among them, the projectile velocity and frictional coefficient have significant influence on the bayonet-chamber depth and the band-barrel reaction force, the quadrant angle and initial deflection have major impact on the bayonet-chamber posture, meanwhile, the barrel-projectile gap playes an important role in all the three results. The results provide a parameter basis to the ammunition rammer design and the motion law of projectile in bore.

Research on Response Characteristics of Muzzle for Self-propelled Antiaircraft Gun Firing on the Move

XIE Run, YANG Guo-lai

2014, 35(8):  1158-1163.  doi:10.3969/j.issn.1000-1093.2014.08.004

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To study the response characteristics of muzzle for self-propelled antiaircraft gun firing on the move, a dynamic model of self-propelled antiaircraft gun is established based on multi-body system theory, vehicle terrame chanics and gun launch dynamics. The stochastic road irregularities are simulated by means of the sinusoid superposition method. The muzzle responses in the conditions of driving and launch are obtained by numerical calculation. The effects of driving speed, road grade, launching load and firing angle on muzzle response of self-propelled antiaircraft gun are analyzed. The finite element method and the collision theory are used in consideration of the structural nonlinearity factor of antiaircraft gun, and the flexible barrel model and the contact model of ball bearing are applied to the dynamic model. The results indicate that the muzzle dynamic response increases with the increase in travel speed and road grade. The muzzle disturbances may vary greatly under the different conditions of launching. The results provide reference basis for grasping law of muzzle disturbances for self-propelled antiaircraft gun firing on the move.

Real-time Impact Point Prediction of Rocket Projectile Based on Perturbation Theory

LI Chao-wang, GAO Min, SONG Wei-dong

2014, 35(8):  1164-1171.  doi:10.3969/j.issn.1000-1093.2014.08.005

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The 6-degrees of freedom trajectory equations for rocket projectiles are established, and a new real-time impact point prediction (IPP) approach is proposed based on perturbation theory. Assuming that the rocket projectile flies along the nominal trajectory without disturbance, the detailed calculation process of the dispersion in impact point is presented. The prediction coefficient is calculated using a fire control computer on the ground, and IPP is carried out using the rocket-borne computer during flight. As a result, the IPP process is simplified. Finally, the simulation and flight tests of 122 mm rockets is accomplished. The results show that its prediction precision is higher under any condition. At the same time, the results demonstrate that the time consumed to predict the impact point is about 167 ns, which is much less than the control cycle time of 2 ms.

Numerical Simulation of Bullets Penetrating into Gelatin Target with Hard/Soft Composite Armor

LUO Shao-min， XU Cheng， CHEN Ai-jun， ZHANG Xiao-yun， LIU Su-su

2014, 35(8):  1172-1178.  doi:10.3969/j.issn.1000-1093.2014.08.006

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In order to explore the interaction process and mechanism of bullet impacting a gelatin target with hard/ soft composite armor，the penetration of 7.62 mm bullet into composite armor and gelatin is numerically simulated using an FEA method，and the typical phenomena of impacting process and the dynamic response of gelatin target are analyzed. The simulation results show that the formation of the ceramic cone results from the compressive and tensile stress waves. The obvious segmentation and inflection points display on the curve of projectile acceleration. The acceleration reaches its maximum when the projectile penetrates into a ceramic faceplate. The second inflection point appears when the projectile penetrates into PE rear plate. The multi-peaks appear on the velocity curve of PE rear plate due to multiple interfaces on protection layer：When the projectile reaches the maximum acceleration，the first peak appears，and the first pressure peak appears on gelatin interface；the second peak appears when the projectile penetrates into PE rear plate. The propagation of pressure wave in gelatin presents the basic form of spherical wave， and the pressure peak propagation complies with the law of exponential decay.

Optimization of Glide Trajectory of Guided Bombs Using a Radau Pseudo-spectral Method

YUAN Yan-bo， ZHANG Ke， XUE Xiao-dong

2014, 35(8):  1179-1186.  doi:10.3969/j.issn.1000-1093.2014.08.007

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The problem of optimizing the maximum range of a glide guided bomb is studied based on the principle of solving optimal control problems using the Radau pseudo-spectral method. The dynamic model of the guided bomb is nondimensionalized. Combining with the Pontryagin minimum principle, the analytic solution of the optimal control and the first-order necessary condition are derived. The trajectory optimization problem is translated to a nonlinear programming via the Radau pseudo-spectral method. Based on covector mapping principle, an optimality verification method is presented for the numerical solution. Simulation results show that the Radau pseudo-spectral method can provide a highly valuable optimal solution for engineering application. Compared with the conventional maximum lift-to-drag ratio gliding trajectory, the trajectory after optimization can be extended by more than 10%.

Method of Calculation on the Range of Projectiles and Rockets Based on Curved Earth's Surface

ZHONG Yang-wei, WANG Liang-ming

2014, 35(8):  1187-1192.  doi:10.3969/j.issn.1000-1093.2014.08.008

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To study the effects of curved earth’s surface on the ranges of projectiles and rockets, a modified rigid body trajectory model is built based on Kane method in which the curved earth’s surface and the changes in both the size and direction of the gravity acceleration are considered. The concept of geodesic line is introduced to the range calculation of projectiles or rockets. Four calculation methods for the range under the condition of curved earth’s surface are discussed, such as inverse solution of geodetic problem and so on. The range errors calculated with the modified rigid body trajectory model and the ordinary rigid body trajectory model are compared. The result shows that the spheroidal distance algorithm has a high calculation precision in the range of 300 km, and can be used to calculate the range on the curves earth’s surface. The modified rigid body trajectory model is more accurate than the ordinary rigid body trajectory model in the consideration of the curved earth’s surface.

Analysis of LFM Signals and Improvement of IFM System

WANG Hong-xun, WANG Shi-yan, WANG Xing, WANG Hong-wei

2014, 35(8):  1193-1199.  doi:10.3969/j.issn.1000-1093.2014.08.009

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Frequency is one of the key features of radar signals, which is extracted in real-time by an instantaneous frequency measurement (IFM) system in electronic warfare receivers used for RWR/ESM. Linear frequency modulation (LFM) signal is an important signal type and used widely in radar, and its frequency characteristics could not be detected by traditional IFM system. A novel technique is proposed based on improved IFM system for LFM signal feature detection, and a mathematical model of LFM signal passing through IFM system is established based on the operating principle of IFM system. The frequency resolving capacity and the minimum detectable frequency modulation slope are discussed. In the improved IFM system, a phasing detector signal is used as the effective indicating signal of sampling to extract the time of arrival (TOA) and pulse width (PW) features. The analog-digital converters (ADC) instead of polarity quantizer of traditional IFM system are used to sample continuously the outputs of the orthogonal channels. The fuzzy clearness and linear regression algorithms are used for noise smoothing and evaluating the carrier frequency and the frequency modulation slope of LFM signal. Simulation results show that the improved IFM system could extract the LFM signal features in an LFM pulse with higher accuracy, and retains the advantages of original IFM system.

Trajectory Shaping Guidance Law Based on Ideal Line-of-sight

LI Hao, SHE Hao-ping

2014, 35(8):  1200-1204.  doi:10.3969/j.issn.1000-1093.2014.08.010

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When a homing missile tracks a target, it may fail to lock the target because of complicated background. For example, when a missile attacks a target in look-down mode, the missile’ capability of intercepting or acquiring a target is weakened by complicated surface background and clutter. A new modeling method which regards the ideal line-of-sight as the control objective is put forward. And an optimal guidance law is designed based on restraining the terminal direction of relative motion between missile and target and the trajectory overload. The guidance law is used to control the motion of missile in a direction vertical to ideal line-of-sight. The simulation result shows that this method can meet the requirement of terminal trajectory shaping better, distribute the overload more reasonably and decrease the influence of ground background and clutter on target tracking effectively.

Research on Visco-hyperelastic Constitutive Model of EPDM

YANG Xiao-hong, XU Jin-sheng, SUN Jun-li, HU Shao-qing, ZHOU Chang-sheng

2014, 35(8):  1205-1209.  doi:10.3969/j.issn.1000-1093.2014.08.011

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The constant rate uniaxial tension tests and tension-recover tests are conducted to obtain the accurate mechanical property of the EPDM insulation material. A visco-hyperelastic constitutive model is developed based on the mechanical behavior characteristics of EPDM. The method is established by applying the hyperelastic theory which was established under finite deformation condition in combination with linear viscoelastic theory. Then the way to obtain the model parameters is proposed, which is simple and easy to be generalized. The results show that EPDM has the typical hyperelastic mechanical characteristics, and presents a rate-dependent effect. The visco-hyperelastic constitutive model proposed can describe the uniaxial mechanical property of EPDM accurately. The model can provide a theoretical reference for structural integrity analysis of solid rocket motor made of EPDM insulation material.

Dynamics Analysis of AL Plate Subjected to Underwater Impulsive Loads Based on 3D DIC

XIANG Da-lin， RONG Ji-li， HE Xuan， LIU Han， CHEN Peng-wan， FENG Zhi-wei

2014, 35(8):  1210-1217.  doi:10.3969/j.issn.1000-1093.2014.08.012

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A three-dimensional dynamic digital image correlation (DIC) test system is set up based on the digital image correlation(DIC) method. The dynamic response experiment of AL1060 plate with speckles is conducted using the underwater impact loading device, and the out-of-plane displacement of Al target is obtained. The pressure-time histories of shock wave are measured by dynamic high-pressure transducers mounted on an anvil. A two-dimensional axisymmetric simulation model is established, and the formation and propagation of shock wave in water and the deformation process of Al plate are analyzed. The investigation shows that the deformation growth of the target presents an annulus expanding from the boundary to the center, and a shear cracking phenomenon easily appears at the constraint boundary. The calculated real-time deformation of target and the shock wave-pressure history are well in agreement with the experimental data，which confirms that it is feasible to study the underwater shock of plate structure using the underwater impact loading device in combination with 3D DIC.

Poisson’s Ratio of LY12 Aluminum Alloy under Shock Compression

TAN Hua, YU Yu-ying, DAI Cheng-da, TAN Ye

2014, 35(8):  1218-1222.  doi:10.3969/j.issn.1000-1093.2014.08.013

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The physical meaning of Poisson’s ratio is discussed. The relationships among the Poisson’s ratio and the longitudinal and transverse stresses under uniaxial strain shock loadings, and the relationship between the Poisson’s ratio and the sound velocity in quasi-elastic deformation region are presented. Poisson’s ratios of LY12 aluminum alloy materials are calculated based on the sound velocities measured at shock pressures from 20 GPa to 131 GPa. It is found that, while the Poisson’s ratios keep almost constant, i.e., 0.32, before shock-melting happens, it increases rapidly in the shock-melting solid-liquid mixed phase region and approachs the theoretical limit of Poisson’s ratio, i.e., 0.5, as shock-melting completes, which may provide us a useful way for identifying the shock induced melting zone.

Numerical Simulation of Inlet and Outlet Pressures Influencing Internal flow of a Vane Pump

ZHANG Qun-feng， YAN Pan-pan, SHAN Jian-ping, HE Wan-fa

2014, 35(8):  1223-1229.  doi:10.3969/j.issn.1000-1093.2014.08.014

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The internal flow of a lubricant vane pump in aircraft engine is simulated using the computational fluid dynamics software Star-cd to estimate the influences of inlet and outlet pressures on its internal flow. A self-compiled code is called by the subroutines of Star-cd to generate the moving mesh of vane pump, especially to capture the gap shape between vane and stator. Rayleigh cavitation model and Mender's SST k-ω model are used in the simulation. The calculated flow rates are obtained under different inlet and outlet pressures. The simulation results demonstrate that the transient flow rate at the inlet is stable, while the transient flow rate at the outlet fluctuates significantly. The calculated results also demonstrate that the flow rate increases significantly with the increase in inlet pressure. And with the increase in outlet pressure, the back flow is increased and the collapse velocity of cavitation is also increased, resulting in a small reduction in the flow flux.

Dynamic Response of a Clamped Sandwich Beam under Impact of Low-Impulse Mass

JIANG Wen-zheng, LIU Ying

2014, 35(8):  1230-1235.  doi:10.3969/j.issn.1000-1093.2014.08.015

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Considering the coupling effects of face sheets and core, as well as the effects of core material in the deformation of the sandwich beam, an improved analytical model is proposed, and the dynamic response of a fully clamped sandwich beams under the impact of a low impulsive projectile is discussed. The bending effects of the core before the two face sheets arrive at the same velocity are considered in the proposed analytical model, which is different from the previous sandwich beam model. The comparison of experimental and numerical results indicates that the model can well predict the responses of the sandwich beams, and is available for the situation when the sandwich beam deforms.

Research on Self-calibration Algorithm for Attitude Errors of Acoustic Vector Sensor Array

LIANG Guo-long, ZHANG Ke, AN Shao-jun, FAN Zhan

2014, 35(8):  1236-1242.  doi:10.3969/j.issn.1000-1093.2014.08.016

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In practice, the attitude error exists in acoustic vector sensor array (AVSA). The influence of attitude error on the AVSA beam pattern is theoretically analyzed to fully recognize the attitude error. Since off-calibration algorithm is limited to the actual work environment, a self-calibration algorithm of attitude error is proposed. The algorithm can estimate the attitude error parameter and DOA of sources simultaneously by utilizing nonlinear iteration to minimize the objective function. Numerous computer simulations verifieds the good parameter estimation performance and fast convergence rate of the proposed algorithm.

A Novel Method of UUV Path Planning Based on Navigation Error Space

YAN Zhe-ping， ZHAO Yu-fei， CHEN Tao， ZHOU Jia-jia

2014, 35(8):  1243-1250.  doi:10.3969/j.issn.1000-1093.2014.08.017

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The traditional path planning of unmanned underwater vehicle (UUV) frequently ignores the navigation errors which have significant impact on the path safety. To solve the problem, a method of global path planning based on navigation error space (NES) is proposed, which introduces the navigation error into environment model. NES is built, including position, navigation error and environmental information, which translates the stochastic navigation error into deterministic constrains. The error propagation model is applied, and CEP is used to evaluate the positioning accuracy. The path length and sail safety are considered in the objective cost function. An improved A^* based algorithm is applied for searching the optimal path. Simulation experiment of marine environment show that the proposed approach is simple and fast, and path risk is decreased efficiently.

A Dynamic Processing Method of Roll Angle of Small Floating Antenna

CAO Hai-qing， WANG Yu， YAO Zhi-ying， DU Ming-fang

2014, 35(8):  1251-1257.  doi:10.3969/j.issn.1000-1093.2014.08.018

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A dynamic processing method of roll angle of small floating maritime satellite antenna, which is applied in military concealed reconnaissance, is studied. The influence of roll angle on the quality of communication, the relation between azimuth and roll angles as well as the relation between elevation and roll angles are studied in theory. A dynamic processing method of that the compensations of the azimuth and elevation angles are applied to isolate the influence of the roll angle on communication is proposed. The relational expression among AGC, azimuth and elevation is fitted by the least square method based on the sampling data. The proposed method for roll angel of the small floating antenna is feasible by comparing the changes of AGC in the process of dynamic processing to the changes of AGC in the process of 4-axis servo compensation.

Static and Dynamic Simulation and Analysis on PBP Actuator with a Connecting rod Mechanism to MagnifyOutput Angular Displacement

HU Kai-ming, WEN Li-hua, YAN Zhao-qi

2014, 35(8):  1258-1266.  doi:10.3969/j.issn.1000-1093.2014.08.019

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In order to magnify the output angular displacement of piezoelectric bimorph further, a bimorph actuator with a connecting rod mechanism is proposed based on the method of increasing the output angle and torque of piezoelectric bimorph by post-buckled pre-compression (PBP). A static numerical model with a torsion spring on its end is founded. And the rigid-flexible coupling Lagrange equation dynamic model and FEM model both with small rudder are also established. The results indicate a better coincidence between the numerical and FEM models. Statics results show that connection rod mechanism proposed can produce an output angular displacement which is 4 times bigger than that produced by the original PBP driver, and the biggest output angular reaches 26.3°, reducing the output torque. The dynamics results show the transfer and distribution of the interior energy of actuator mechanism. Taking the small rudder in this paper as a driving object, the average output angular velocity reaches 2 000°/s, and the control bandwidth reaches 30 Hz, which are much better than those of the ordinary servo actuator. Therefore, the design and simulation of the proposed actuator can provide the theoretical basis to the development of micro-flight rudder characterized by large displacement, small output torque and high control bandwidth.

Signal Feature Extraction of Aero-engine Turbine Blade Crack Detection

YU Xia, ZHANG Wei-min, QIU Zhong-chao, CHEN Guo-long, ZHAO Dun-hui

2014, 35(8):  1267-1274.  doi:10.3969/j.issn.1000-1093.2014.08.020

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The aero-engine turbine blade is a high precision part. Blade surface crack detection belongs to an irregular surface detection, and is a hotspot and difficulty in the field of non-destructive testing. Taking the unique advantage of eddy current testing into account, a simple，practical and effective differential incentive eddy current probe is designed to detect the prefabricated micro-cracks of aero-engine turbine blades. Since the surface curvature of turbine blade varies, the lift-off effect exists inevitably in the detection process. Therefore, the test results of the detection signal contain noise and multiple singular points. In order to ensure that the important information of defect location is not lost, the combination of the mirror extension empirical mode decomposition（EMD）reconstruction and wavelet singularity detection method is used to process the detected micro-crack signals, filter out the influence of several distortion points on non-cracked positions, and achieve an accurate and effective determination of the micro-crack position of turbine blade. The results show that the method can effectively reduce the noise and interference of detection signal, and extract accurately the feature information of crack signal.

Design and Analysis of Thermal Protection of Complex Structure with High Explosives under Fire Conditions

WU Song， LI Ming-hai， ZHANG Zhong-li

2014, 35(8):  1275-1280.  doi:10.3969/j.issn.1000-1093.2014.08.021

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The complex structure with high explosives may encounter an accidental fire event during storage, transportation, service or use. The objective of thermal protection design is that the highest temperature of explosives in the complex structure should not exceed 343 K(70 ℃) in 30 min under fire condition. Some thermal protection measures are presented by analyzing the main factors that affect the temperature rise of the explosives, which are to reduce the emissivity of shell surface, increase the thermal resistance in structural supports and use phase change materials for heat leading. The thermal protection effects of different schemes are computed and analyzed using FEM numerical analysis method. The results show that single measure can only reduce a local temperature, and the combining measures can satisfy the design requirement.

Using Wavelet Scalogram Method to Analyze Cracked Rotor System with Fractional Order Damping

LI Zhi-nong, WANG Hai-feng, HE Xu-ping, XIAO Yao-xian

2014, 35(8):  1281-1287.  doi:10.3969/j.issn.1000-1093.2014.08.022

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A fault diagnosis method of cracked rotor system with fractional order damping based on wavelet scalogram is proposed through the model of cracked rotor system based on the fractional calculus and wavelet scalogram. The characteristics of wavelet scalogram and reassigned scalogram from different crack depth in rotor system with fractional order damping are discussed. The simulation results show that the derivative order of damping and the crack depth have great influence to the dynamics characteristics of rotor system. The optimal derivative order of damping can be determined by adjusting the fractional order. The proposed method is sensitive to crack fault, which can effectively extract the crack fault information in the rotor system. Finally, the effectiveness of the proposed method is verified through the experiment rig. The experimental results are very consistent with the simulation results, and the proposed model of cracked rotor system based on the fractional calculus is correct.

Gearbox Vibration Signal Fault Feature Extraction Based on Ensemble Empirical Mode Decomposition andChoi-Williams Distribution

WANG Wei-guo, SUN Lei

2014, 35(8):  1288-1294.  doi:10.3969/j.issn.1000-1093.2014.08.023

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For gearbox fault feature extraction, a novel method based on ensemble empirical mode decomposition and Choi-Williams distribution for gearbox vibration signal extraction is proposed. Firstly, vibration data are decomposed into several intrinsic mode functions (IMF) with EEMD, and IMFs are sorted by kurtosis criterion, then CWD is applied to the selected IMF which kurtosis is larger than others, the Choi-Williams distribution features in time, frequency and amplitude domains of the original signal can be extracted. On the basis of discussing teeth break and crack vibration fault mechanism of gearbox, the proposed method is used to analyze the vibration signal of the actual fault gearbox. The result shows that this method can efficiently extract the fault information and have great importance for condition recognition and fault diagnosis of gearbox.

Research on Maintenance Scheme of a Trans-supersonic Wind Tunnel Augmentation Ejector Based onFuzzy Evaluation Method

DONG Bin， WANG Tao， XU Yong-cheng， XIA Ming-zhu

2014, 35(8):  1295-1300.  doi:10.3969/j.issn.1000-1093.2014.08.024

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A fuzzy evaluation model is proposed for the fuzziness of evaluation indexes of maintenance schemes in the maintenance scheme evaluating process of a trans-supersonic wind tunnel augmentation ejector, and the calculation method for evaluating confidence index is concluded. This model is used to qualitatively and quantitatively analyze 4 maintenance schemes in terms of safety, economics, disassemblability and assemblability, human factors engineering, timeliness, and maintenance quality, and the optimized maintenance scheme of the trans-supersonic wind tunnel augmentation ejector is obtained. At the same time, the maintenance schemes of other wind tunnel systems are also able to be evaluated to confirm the optimized maintenance schemes with this model, which promotes scientific nature of choosing optimal maintenance schemes.

Effect of Gear Backlash on Positioning Precision of Manipulator End-effectors

AN Kai

2014, 35(8):  1301-1307.  doi:10.3969/j.issn.1000-1093.2014.08.025

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The probability of that the positioning error of the end-effectors in a manipulator with gear backlash meets the desired accuracy is studied. The advantages and disadvantages of existing gear backlash models are analyzed, and a random variable model of gear backlash is presented based on the improvement of one of the models. A random model of positioning errors of the manipulator end-effectors is derived by taking the random variable model as angular displacement errors of 3-joint manipulator. A simplified model expressed by a quadratic function of angular displacement errors is obtained by approximating the random model with Taylor's formula. The maximum and minimum of the positioning error in joint space are discussed as well. The probability of that the positioning error of the manipulator end-effectors meets the desired accuracy is presented according to four cases, which provides basis for route planning and task optimization in multi-phase mission system.

Research Notes

Design of Plastic Objective Lens for Low-light Night Vision System

ZHANG Liang, PAN Xiao-dong

2014, 35(8):  1308-1312.  doi:10.3969/j.issn.1000-1093.2014.08.026

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The design of objective lens for low-light night vision system with plastic and glass optical elements is introduced. The optical athermalization method is used for temperature change and aberration balancing. The operating wavelength is in the range from 0.65 μm to 0.95 μm, the field of view is 40°, and F-number is 1.2. The modulation transfer function (MTF), temperature adaptability and weight of night vision optical system are analyzed and evaluated by the CODE V optical design software. The design result indicates that MTF of all FOVs is more than 0.4 at 40 lines per millimeter in the total temperature range and the weight of all lenses is less than 20 g. The optical system obtains weight reduction and better image quality.

Research on the Identification Device of Copper Crusher Gauge

PAN Xiao-bin, TAN Le-bin, KONG De-ren

2014, 35(8):  1313-1317.  doi:10.3969/j.issn.1000-1093.2014.08.027

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In order to distinguish 1 cm² copper crusher gauge, a special experimental device which can supply required pressure source by volume expansion is proposed and designed. An interior ballistic model of the device is set up and simulated based on the interior ballistic analysis and the flow equation of the working chambers. The pressure and flow characteristics of propellant gas between bore and chamber are obtained. And the influences of initial volume and position of the high pressure chamber on its maximum pressure are studied. The maximum pressure of the high pressure chamber can be adjusted to about 39.0 MPa under the condition of the known parameters. Compared with the experimental results, the maximum deviation is 4.9%. The device can meet the requirement of identifying copper crusher gauge.

Modeling and Research on Penetration Effectiveness Evaluation of Ballistic Missile Considering the Effect of Decoys

WANG Min-le, LI Yong

2014, 35(8):  1318-1323.  doi:10.3969/j.issn.1000-1093.2014.08.028

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The evaluation of penetration effectiveness of ballistic missiles under the cover of decoys is an important issue. The missile penetration probability is used as an evaluation index of penetration effectiveness. Based on the different decoy jamming and anti-missile interception strategy, the penetration effectiveness models of single and multiple ballistic missiles are built. Considering the effect of decoys, the penetration effectiveness of multiple ballistic missiles is quantitatively studied. At last, the results of a sample are analyzed, and the models are verified, from which some valuable conclusions are got. The research result has a certain reference value to the simulation and evaluation of penetration ability of ballistic missile.

Influence of Deflector Baffle on Performance of Banki Wind Turbine

MAO Zhao-yong, WEI Chao, HUANG Wei-chao, FAN Yu

2014, 35(8):  1324-1328.  doi:10.3969/j.issn.1000-1093.2014.08.029

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Banki wind turbine is a small wind turbine which is suitable for running at low wind speeds, but its overall efficiency is low because of the negative torque in the windward direction. An improved Banki wind turbine with an arc-type deflector baffle arranged in the upwind direction is proposed. In order to investigate the influence of the deflector baffle on the aerodynamic performances and power generation of the turbine, the two-dimensional unsteady flow of the turbine is computed by using sliding mesh. The results show that the deflector baffle can be used to reduce negative torque on the blades in the upwind half cycle, and the power coefficient of the turbine can be increased by 66.9%.