Table of Content

31 May 2017, Volume 38 Issue 5

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Contents

2017, 38(5):  0. 

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Paper

Research on Integrated Control of Steering Stability of Multi-wheel Independent Electric Drive Vehicle

LIAO Zi-li， YANG Gui-bing， GAO Qiang， YUAN Dong

2017, 38(5):  833-842.  doi:10.3969/j.issn.1000-1093.2017.05.001

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An integrated control method based on direct yaw moment control (DYC) is designed to improve the steering stability of multi-wheel independent electric drive vehicle, which includes the upper coordinated controller and the lower controller. The lower controller is optimized by designing a distribution with pre-distribution, driving skid-resistance control and compensation. The optimized torques of the system and the driving wheels keep the performing error of yaw moment minimal. The double lane change experiments of a prototype vehicle on low friction road and high friction road show that the integrated controller can improve the steering stability significantly and follow the desired tracks. Key

Design and Dynamics Analysis of Vertical Ammunition Cabin for Armored Vehicle

ZHANG Lei-yu, LI Jian-feng, YANG Yang

2017, 38(5):  843-851.  doi:10.3969/j.issn.1000-1093.2017.05.002

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The vertical ammunition cabin possesses the functions of ammunition storage, recognition and automatic selection. The ammunition vertically placed in the cabin is circularly dragged along the optimum ammunition trajectory by the drive chain. In order to analyze the dynamic properties of drive chain and the stability of ammunition, all links of drive chain and the double-row rollers of ammunition rack are simplified as spring-damper elements. The full dynamics models of drive chain and the stability model of ammunition are established by use of multi-body dynamics and kineto-elastodynamics methods. A numerical simulation of the full dynamics models is performed by adopting Matlab software. The stability model of ammunition is solved. Simulated results show that the velocity and acceleration of drive chain fluctuate within a small range. The dynamic response and drastic characteristic of centrifugal forces are dominated by the shape feature of the trajectory. The normal stability of ammunition is influenced by the drastic characteristic. The tangential stability is determined by the inertia forces of ammunition and the dynamic parameters of drive chain. The analysis shows that the ammunition has high normal and tangential stability. The tangential accelerations of chain and the normal accelerations of ammunition rack are measured. It can be found that the measured data are consistent with the simulated results. Key

Design and Optimization of Spatial Cylindrical Cam of Synchronous Movement Mechanism of Opposed-piston Axial Cylinder Engine

YE Ying， ZHAO Zhen-feng, FU Dai-qiao， ZHANG Fu-jun

2017, 38(5):  852-858.  doi:10.3969/j.issn.1000-1093.2017.05.003

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The optimization design of space cylindrical cam synchronization mechanism of opposed piston in axial cylinder two-stroke engine is studied. In order to optimize the performance of engine, a model of space cylindrical cam is established, the pressure angle and space cylindrical cam profile are optimized and designed, and the movement law of engine piston is optimized. The performance parameters of the engine under different piston displacement curves are calculated by using GT-power simulation software. And the influence of piston displacement curve on the performance parameters of engine is analyzed. The calculated results show that the movement law of piston is optimized and the engine performance is improved by optimizing the space cylindrical cam profile. With the change in the direction of piston displacement curve, the performance of engine is first increased and then begins to decline. An optimal design method of space cylindrical cam of synchronous motion mechanism in the opposed piston engine is obtained. Key

Analysis of Impinging Characteristic of Distributed Power Supply System during Launching of Electromagnetic Rail-gun

ZHANG Miao, SHEN Na， TIAN Hui

2017, 38(5):  859-866.  doi:10.3969/j.issn.1000-1093.2017.05.004

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During the launching of electromagnetic rail-gun, the distributed power supply system would suffer more than 30 kA pulse current and more than 5 kV pulse voltage within 2 ms, which has great effect on the critical components of power supply system. Research on the impinging characteristic of distributed power supply system during the launching of electromagnetic rail-gun is very important. A distributed pulse power supply system model with dynamic load variation is established. The impinging characteristics of the distributed pulse power supply system and its working characteristics after the failure of critical components are simulated using Pspice software, and the analysis results are compared with the experimental results. The results show that, during the launching of electromagnetic rail-gun, the capacitor bank of distributed power supply system would suffer large reverse current and reverse voltage after thyristor breakdown, which causes serious damage to the capacitor bank. After the wave modulated inductance is breakdown, the output waveform pulse width of fault module is similar to the output waveform of capacitor bank, and it causes the pulse width of output waveform decrease peak value increase（di/dt of current that though the thyristor increase）, it may cause the high voltage silicon rectifier stack of thyristor positive flow burned. The simulated results are in good agreement with the experimental results, which proves that the power model of electromagnetic rail gun is very close to the practical model, and the result is more accurate and credible. Key

Rapid Impact-point Prediction Modeling Based on Perturbation Theory and Piecewise Prediction Control Method

WANG Yu, YU Ji-yan, WANG Xiao-ming

2017, 38(5):  867-876.  doi:10.3969/j.issn.1000-1093.2017.05.005

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The rapid and accurate impact-point prediction is a key to correct or guide a high-spinning projectile， and the impact-point prediction based on perturbation(PP) with base trajectory can balance the calculation efficiency and precision. As the parameters of the perturbation model cannot be calculated rapidly with the variation in environment and target, a method combining the perturbation theory and step approximation method is proposed to calculate the proper launching parameter and base trajectory quickly; and an equation of the model parameters which can be calculated by iteration is deduced to fast modeling under arbitrary destination and condition. Simulations and uncontrolled experiment were carried out to verify the feasibility of the proposed method. The results show that the base trajectory and perturbation model can be established. Compared with the modified point-mass trajectory (MPT) method, the predicted error of ascending trajectory of perturbation method is smaller and the predicted error of descending one is larger. Considering the characteristics of PP and MPT methods, a piecewise prediction method combining PP and MPT is proposed. According to the Monte Carlo simulation, the correcting effect of PW method is better than those of PP or MPT method. Key

Experimental Investigation on Damage of Glassfiber Sandwich Structure under Explosion and Fragment Loadings

LI Dian， HOU Hai-liang， DAI Wen-xi, ZHU Xi， LI Mao， CHEN Chang-hai

2017, 38(5):  877-885.  doi:10.3969/j.issn.1000-1093.2017.05.006

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In order to explore the protection ability and damage mechanism of glassfiber sandwich bulkhead under explosion and fragment loadings，the deformation and failure tests of glassfiber sandwich structure were performed using cast TNT and prefabricated fragments. The damage characteristics of glassfiber composite sandwich structure，of which protection ability is quantitatively compared with those of aramid and high-strength polyethylene composite sandwich structures，are studied，and the failure mode of each layer composite sandwich structure and its corresponding failure mechanism are analyzed. The results show that E-glass core is required to be 1.37 times and 2.50 times heavier than aramid core and high-strength polyethylene core，respectively，when sandwich structure is applied to resist explosion and fragment loadings. The failure mode of front panel is co-determined by three factors，including shock wave，fragment load,and core constraint. Fragment load plays a major role on core failure mode，the failure mode of rear panel is related to core impact and fragment load. The shock wave and core impact are surface loads，which lead to the bending deformation of front and rear panels，the fragment load is point load，which leads to the local piercing holes on panel and core，and the core constraint limits the deformation space of the front panel. Key

Experimental Study of Influence of Boron Content on Explosion Performance of Fuel-air Explosive

XU Min-xiao, LIU Da-bin, XU Sen

2017, 38(5):  886-891.  doi:10.3969/j.issn.1000-1093.2017.05.007

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In order to know the influence of boron content on explosion performance of fuel-air explosive, the mixture of boron and aluminum is added to fuel-air explosive with formulation of B/Al/PO/petroleum ether/IPN, and a static explosion is performed to study the influence of boron content in the mixture on the explosion overpressure, impulse and heating effect. The test results indicate that the explosion overpressure, impulse and heating effect increase firstly and then decrease with the increase in boron content in fuel air explosive (FAE). When the mass fraction of boron is 12.5%, the ground impulse of the explosive reaches to 112.51 KPa·s, which is 6.16% higher than that of the aluminized FAE. When the mass fraction of boron is 12.5%, the explosion temperature reaches to 1 250 ℃, which is 20 ℃ higher than that of the aluminized FAE. When the mass fraction of boron is 12.5%, the biggest thermal radiation reaches to 68.266 kJ/m², which is 7.14% higher than that of the aluminized FAE. Adding some boron powders to Al-B mixture can improve the underwater detonation energy of the aluminized FAE. Key

Simulation of Electrostatic Cone Discharge in Propellant Production Process

WEI Shui-ai， BAI Chun-hua， LI Chun-guang

2017, 38(5):  892-899.  doi:10.3969/j.issn.1000-1093.2017.05.008

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Electrostatic cone discharge is an important discharge type causing propellant explosion. In order to study the discharge rule in the production process, the ANSYS finite element model is used to simulate the electrostatic field in the storage and transport hopper of the single-base gun propellant based on Gauss theorem of electrostatic field, and the simulated results are compared with the experimental results. The distribution of electrostatic field and its variation with the thickness of single-base gun propellant are simulated. Results show that the largest electric field intensity is at the bottom of the single-base gun propellant hopper, and the electric field intensity on material surface is minimum.The maximum potential appears in the inner of material, rather than on the material surface. When the material thickness is 0.05 m, the maximum field intensity at the bottom of is 6.92×10⁶ V/m , which is greater than the air breakdown strength. This shows that the electrostatic cone discharge may happen at the bottom of the hopper when the hopper is just tank filled with propellant. The electric field intensity in hopper also increases with the increase in the thickness of material. When the propellant thickness is increaseed to 0.29 m, the maximum field intensity at the bottom is increased to 1.41×10⁷ V/m, the field strengths on side wall and material surface also increase, the cone discharge is more frequent, and the fire risk of propellant is greater. Key

Robust Terminal Guidance Law with Autopilot Lag and Impact Angle Constraints

YANG Jing， WANG Xu-gang， WANG Zhong-yuan， CHANG Si-jiang

2017, 38(5):  900-909.  doi:10.3969/j.issn.1000-1093.2017.05.009

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A novel robust impact-angle-constrained guidance law with autopilot lag is proposed based on integral sliding mode and dynamic surface control for guided projectiles. The inner-loop autopilot is characterized by an uncertain second-order dynamics. The sliding mode variable is defined as a combination of the line-of-sight (LOS) rate and the LOS angle error with time-to-go in order to realize the guidance strategy and achieve a good acceleration performance during interception. The smooth nonlinear disturbance observer is adopted to obtain the model discrepancies from target maneuver and the speed variation of target and interceptor. The stability of LOS rate and the LOS angular deviation is proved in the sense of the uniform boundedness and ultimate boundedness. Simulated results show the effectiveness and superiority of the proposed robust terminal guidance law compared to the trajectory shaping guidance law and the nonsingular terminal guidance law. Key

Simulation of Explosion Overpressure Distribution for Non-symmetry Cloud Detonation

WANG Ye, BAI Chun-hua , LI Jian-ping, CHEN Feng-yun

2017, 38(5):  910-916.  doi:10.3969/j.issn.1000-1093.2017.05.010

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In order to study the distribution characteristics of overpressure field for non-symmetry detonation, the process of non-symmetry cloud detonation is simulated by LS-DYNA code. The simulated and experimental results are compared. The changing rules of overpressure with distance in three directions, including 0°, 90°and 180°, are obtained. The influences of different angles of inclined cloud on overpressure are studied. Results show that there is an angle between cloud and ground. The track of shock wave presents inclined spheroidicity. The attenuation properties of overpressure in different directions are different. The peak overpressure in the direction of 0° is larger than those in other directions, and the peak overpressure in the direction of 180° is the smallest. The attenuation velocity in the direction of 0° is higher than those in other directions, and the attenuation velocity in the direction of 180° is lower than those in other directions. When the angle of inclined cloud increases from 0° to 8.27°, the peak overpressure is decreased by 7% averagely in the range from 13 m to 30 m in the direction of 0°. The peak overpressure remains nearly unchanged in the direction of 90°, but is increased by 8% averagely in the range from 13 m to 15 m in the direction of 180°. The peak overpressure is decreased by increasing the angle of inclined cloud. Key

4-D Angle Estimation for Bistatic MIMO Radar

CHEN Xian-zhou， YANG Xu, CHEN Zhou， BAI Lin， FANG Hai

2017, 38(5):  917-923.  doi:10.3969/j.issn.1000-1093.2017.05.011

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A new approach to high resolution estimation of four-dimensional (4-D) angle of multiple narrowband far-field signals is presented for bistatic multiple-input multiple-output (MIMO) radar with double L-shaped arrays. The spatial noise can be eliminated and the angle estimation performance is improved by constructing the matched array data and making full use of the cross-correlation matrix. The proposed method decouples the two-dimensional (2-D) direction-of-arrival (DOA) or 2-D direction-of-departure (DOD) estimation problem into two successive one-dimensional (1-D) estimation problems, and only requires eigenvalue decomposition of lower dimensional matrix, which can reduce the computational burden. The received or transmitted elevation angles are estimated using the eigenvalues, and the corresponding received or transmitted azimuth angles are estimated through the virtual array response matrix constructed by the corresponding eigenvectors. Numerically simulated results show that the proposed method can accurately estimate the 4-D angle of multiple spatial targets with lower computational complexity, and 2-D DOA or 2-D DOD could be paired automatically. The proposed method has better angle estimation performance in the situation of low signal-to-noise ratio and short data length. Key

Experiment of New Protype Group Ⅲ-nitride UV Image Converter Tube and Evaluation of Detectable Distance of Missile ApproachWarning System with It

REN Bin, JIANG Zhao-tan, GUO Hui, SHI Feng, CHENG Hong-chang, BAI Xiao-feng, SHEN Zhi-hui, YANG Xiao-bo, ZHOU Yue, CUI Mu-han

2017, 38(5):  924-931.  doi:10.3969/j.issn.1000-1093.2017.05.012

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A superior ultraviolet image converter tube made of Ⅲ-nitride semiconductor material was developed for missile approach warning (MAW) system. The Al mole fraction, film thickness and P-type doping level parameters which have the effects on the photoelectric emission performance of photocathode were determined. High resolution X ray diffractometer and ultraviolet spectrometer are used to analyze the structural and optical characteristics of photocathode. A relative flat and high quantum efficiency with small fluctuation in the wavelength range from 220 nm to 270 nm is obtained, the radiation sensitivity is 39.7 mA/W at 266 nm wavelength, and the spectral response begins to fall from 270 nm wavelength. According to the spectral radiation sensitivity and detectable distance model based on signal-to-noise ratio, MODTRAN atmosphere transmittance simulation software is used to calculate the operating range of MAW system with image converter tube by means of iteration solution. The calculated result shows that the operating range of MAW system can be up to 7.1 km. Key

Node Localization Algorithm Based on Hop-count Quantization in Wireless Sensor Networks

ZHANG Shi， ZHANG Bai-hai， WANG Fei-fan， GUAN Zi-xiao

2017, 38(5):  932-939.  doi:10.3969/j.issn.1000-1093.2017.05.013

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A novel algorithm based on hop-count quantization and extended Kalman filter based on multidimensional scaling (MDS-HE) is proposed to improve the localization accuracy of nodes in wireless sensor networks. The integer hop-count can be transformed into a real number hop-count by partitioning a node's one-hop neighbor set into three disjoint subsets and estimating the distance between nodes by the areas of the intersection regions of hop ring segmentation. The transformed real number hop-count is a more accurate representation of distance between nodes. The real number hop-count matrix is applied to the multidimensional scaling (MDS) method, and the extended Kalman filter is applied to refine accurately the coordinates of nodes. The localization performance of MDS-HE algorithm is simulated and analyzed in WSNs which is composed of nodes deploying randomly over a region. Simulated and experimental results show that the performance of the MDS-HE algorithm outperforms the DV-Hop method and the classical MDS method in the case of different number of nodes. The MDS-HE algorithm is exceedingly accurate in case of the enough anchor nodes. Key

Sonar Image Segmentation Fusion of Multi-scale Statistical Information FCM Clustering and MRF Model in Wavelet Domain

XIA Ping, REN Qiang, WU Tao, LEI Bang-jun

2017, 38(5):  940-948.  doi:10.3969/j.issn.1000-1093.2017.05.014

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Because of poor quality, weak feature information, and difficult target segmentation in sonar image, a sonar image segmentation algorithm based on fusing the fuzzy C-means (FCM) clustering of multi-scale statistical information and Markov random field (MRF) in the wavelet domain is proposed. In the wavelet domain, the low-frequency information depicts the clustering of pixels in different regions, and the high-frequency information reflects the texture feature in that direction. The proposed algorithm selects FCM initial cluster center from the low-frequency sub-band statistical peak value, and FCM algorithm is used for the pre-segmentation of sonar image and the suppression of the noise to improve the accuracy of pre-segmentation. The algorithm is used to construct multi-scale MRF model, and the correlation of inter-scale node marks is characterized by first order Markov. The intra-scale label connection among the description coefficients of two-order neighborhood system is constructed, double-point Multi-level Logistic (MLL) model is used in the label field, and Gauss model is used in the same-marked coefficient characteristic field, thus remeding the described shortfalls of hierarchical and silhouette information in MRF algorithm. The algorithm uses iteration condition model (ICM) algorithm to obtain its label fields for the minimum energy to realize the sonar image segmentation. The experimental results show that the proposed algorithm is better than FCM algorithm and MRF model algorithm, and the clarity and precision of the edge and details in the segmented sonar image are improved in a certain degree. Key

Numerical Research on Interaction between Control Surfaces and Main Cavity of Supercavitating Vehicles

ZHOU Hou-cun， XIANG Min， ZHANG Wei-hua

2017, 38(5):  949-958.  doi:10.3969/j.issn.1000-1093.2017.05.015

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The homogeneous multiphase model and volume of fluid (VOF) method are used to simulate the interaction between control surface and main cavity of supercavitaing vehicle (SCV) under different flow patterns of cavity and angles of attack of control surface. Numerical result shows that the vehicle cavity shape affects the submersion depth of the control surfaces, and the variation of submersion depth is up to above 50 percent. The hydrodynamics of control surface is obviously affected by the variation of submersion depth. The length of main cavity is enlarged by 3 percent in average due to the presence of control surface, the cross shape of main cavity could be significantly changed when there is an angle of attack of the control faces, and the cavity shape of SCV experienced a worst deformation under a base closure cavity flow pattern. The interaction between control surface and main cavity of supercavitating vehicle should be taken into consideration during the design process of cavity flow pattern and control law. Key

Design of Fast Beam Forming of Improved Circular Planar Array

YU Di-fei， ZHANG Chun-hua， HUANG Yong

2017, 38(5):  959-967.  doi:10.3969/j.issn.1000-1093.2017.05.016

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In order to reduce the computational complexity of beam forming of 3D imaging sonar based on circular planar array, a method of improving the array design and optimizing the beam azimuth is proposed. The improved circular array consists of a plurality of linear arrays passing through the center, and the beam forming is equivalent to the superposition of the beam forming of all the linear arrays. By optimizing the beam azimuth, the beam forming process of each linear array is equivalent to a one-dimensional fast Fourier transform operation of equal length. The simulated results show that the beam forming computation of the improved circular array is significantly lower than that of the direct calculation. The use of improved circular array can significantly reduce the complexity of the signal processing system and improve the comprehensive performance of 3D imaging sonar. Key

Numerical Investigations on Water-entry Cavity of Half Hydrophobic-half Hydrophilic Sphere

SUN Zhao， CAO Wei， WANG Cong， LU Zhong-lei

2017, 38(5):  968-977.  doi:10.3969/j.issn.1000-1093.2017.05.017

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The water entry of a solid sphere impacting on a liquid surface has challenged researchers for centuries and remains of interest to the researchers today. A simulation study of the water entry cavity of half hydrophobic-half hydrophilic sphere is performed. Particular attention is given to the simulation method based on solving the Navier-Stokes equations coupled with VOF model and CSF model. The numerical results are in agreement with the experimental results, thus validating the suitability of the numerical approach to simulate the water entry of sphere under different wetting conditions. Based on this method, the development of cavity created by the half hydrophilic-half hydrophobic sphere is investigated. Results show that the water entry of half hydrophobic-half hydrophilic sphere creates an asymmetric cavity and “cardioid” splash, which causes the sphere to travel laterally from the hydrophobic side to the hydrophilic side. Further investigations show that the fluid film presents during initial stage of impact, and on the half hydrophobic sphere, the fluid film detaches from the sphere to lead to cavity formation; on the half hydrophilic sphere, the fluid film moves up on the sphere surface and gathers at the vertex of the sphere, forming a wedge flow. The wedge flow moves and finally impacts on the opposite side of the cavity so as to cause “cardioid” splash. In addition, the total hydrodynamic force coefficient is investigated as a result of the forces acting on the sphere during water entry dictated by the cavity formation. Key

Study on Correlation between Plasma Property and Weld Penetration in Laser-arc Hybrid Welding

CHEN Shi-xian， LIU Shuang-yu， ZHANG Hong， LI Yan-qing， LIU Feng-de

2017, 38(5):  978-985.  doi:10.3969/j.issn.1000-1093.2017.05.018

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The plasma radiation spectrum and the shape of arc are collected by using the spectrometer and the high speed camera in the process of two-pulse laser-arc hybrid welding. The plasma electron temperature and electron density are calculated based on Boltzmann plotting method and Stark broadening method, and the electron temperature and electron density at different pulse durations and different frequencies of pulse arc are investigated. Based on the spectral analysis and the high speed image, the plasma physical properties of laser-arc two-pulse hybrid welding are studied. The results show that the arc shrinks and the brightness increases with the increase in laser pulse duration, the electron temperature decreases and the electron density increases with the increase in laser pulse duration, the penetration depth increases, the intensity of spectrum increases and the nitrogen content in the weld decreases; the arc volume becomes larger than before, the brightness increases with the increase in pulse arc frequency, the electron temperature decreases, the electron density decreases, the penetration depth decreases, and the characteristics of the arc welding at the upper part of the weld zone are obviously enhanced. Key

Analysis of Influencing Factors on Reliability of Varable Depth Submarine-launched System Based on Multivariate StepwiseRegression

HU Song-wei

2017, 38(5):  986-994.  doi:10.3969/j.issn.1000-1093.2017.05.019

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Reliability of underwater varable depth launching system is affected by various influencing factors. The weight and offsetting of projectile are studied by multivariate stepwise regression analysis method, and the second-order algorithm of the models is established. Design deviation, charge performance deviation and environmental factos are taken into account. The relativity analysis for each factor is carried out based on the live firing performance test information of a certain type submarine-launched missile. The effects of the influencing factors, correlation coefficients of each factor and best regression subset are discussed. The results of the regression analysis accords well with the live firing phenomena. Based on this method, the experimental results indicate that the estamated error standard deviation of functional reliability parameter is improved. Multiple stepwise regression method improves the estimation precision. It is feasible and effective to analyze the influencing factors. Key

Research on Defect 2-D Inversion Based on Gradient Tensor Signals of Metal Magnetic Memory

CHEN Hai-long， WANG Chang-long， ZUO Xian-zhang， ZHU Hong-yun

2017, 38(5):  995-1001.  doi:10.3969/j.issn.1000-1093.2017.05.020

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Metal magnetic memory (MMM) technology is a nondestructive detection method which is used for early diagnosis of microscopic damage and stress concentration. Since the defect profile is difficult to reconstructed by the existing methods, an analysis method based on magnetic gradient tensor is proposed. A magnetic gradient tensor measuring method is designed based on the analysis of measuring essential factors of magnetic gradient tensor, and a characteristic parameter of horizontal gradient modulus is used to estimate the damage location and boundary by horizontal gradient modulus maximum value. The experimental results of crack 2-D inversion show that the proposed method based on magnetic gradient tensor is not influenced by detection direction, and it is an effective and feasible approach for damage two-dimensional inversion. Key

Research on Simulation of Mission Completion Success Probability Assessment for Random Phased-mission

CAO Wen-bin， JIA Xi-sheng， HU Qi-wei， CHEN Bing

2017, 38(5):  1002-1010.  doi:10.3969/j.issn.1000-1093.2017.05.021

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Phased-mission system extensively exists in modern industrial and military fields, and it is of great practical significance to get its mission completion success probability for system performance evaluation and mission scheduling. Taking some special characteristics of mission profile of weapon systems into consideration, the mission completion success probability assessments of two kinds of missions under random condition are addressed. The simulation procedures of interruption inadmissible and interruption permitted random phased-missions subjected to random common-cause failures are proposed. Additionally, the simulation procedures are achieved by Matlab programming. An illustrative example is presented to verify the validity of the proposed procedures. The effects of parameters associated with phased-mission on the mission completion success probability are discussed. The results show that the proposed method can be adopted to assess the mission completion success probability of interruption permitted or inadmissible random phased-mission, and provides an alternative approach to success completion probability assessment of complicated mission. The reasonable mission scheduling can improve system's mission completion success probability which is shown to be important for practical equipment support and management. Key

Dynamic Scheduling of Battlefield Rush-repair Tasks under Uncertainty in Offensive Operation

CHEN Wei-long, CHEN Chun-liang, CHEN Kang-zhu, LIU Yan

2017, 38(5):  1011-1019.  doi:10.3969/j.issn.1000-1093.2017.05.022

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The dynamic scheduling of battlefield rush-repair tasks is studied in consideration of many damaged equipment, the limited battlefield rush-repair time and power in the integrated offensive operation, which combines battlefield rush-repair, accompanied logistics and task dynamic scheduling. The dynamic battlefield-rush-repair task scheduling under uncertainty, which is a real military problem, is put forward. A mathematical model is established, and the key influence factors are analyzed. A variant genetic algorithm is designed to solve the problem according to its characteristics. A scheduling example with 15 equipment to be repaired and 3 repair groups is solved by using Matlab. The results of example show that offensive forces can get more combat time to participating in offensive operation again about 77 hours through implementing dynamic scheduling of battlefield rush-repair tasks. And it can greatly reduce decision time, decision workload and subjective decision risk. Key

An Investigation of Fluctuating Pressure Environment around Rocket Fairing with Different Curvetypes

ZHAO Rui, RONG Ji-li, LI Yue-jun, LI Hai-bo

2017, 38(5):  1020-1026.  doi:10.3969/j.issn.1000-1093.2017.05.023

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The surface fluctuating pressure environments of the rocket fairings with different curve types, namely normal spherically blunted cone, power series cone and von Karman cone, are systematically investigated by large-eddy simulations (LES). For all the three curve types, the peak of fluctuating pressure is found at a region where shock/separation bubble interacts at a transonic Mach number. The location of the maximum value is consistent with the time-averaged station of shocks. Compared with the fluctuating pressure environment of normal spherically blunted cone, the range and peak of root-mean square pressure coefficient C_{p_rms} are diminished, with the peak value being decreased by 17% for both power series cone and von Karman cone. In particular, serious fluctuating environment could also be induced by the expansion fan, where significant flow acceleration and deceleration occur. The reattached turbulent boundary-layer develops more quickly for normal spherically blunted cone, with its noise magnitude being 10 dB larger than others. Key

Research Notes

Coordinated Control of High Speed Electric Drive Tracked Vehicle

SHENG Hui, GAI Jiang-tao, LI Chun-ming, DU Ming-gang, SHUAI Zhi-bin

2017, 38(5):  1027-1034.  doi:10.3969/j.issn.1000-1093.2017.05.024

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A dynamic coordinated control strategy of mechanical brake, motor and electro-hydraulic retarder is proposed for the torque response of composite braking of mechanical brake, motor and electro-hydraulic retarder in high speed electric drive tracked vehicle. The steady-state braking torque is assigned based on braking requirement and vehicle speed, and the dynamic response characteristics of three executive components are considered comprehensively. Based on the dynamic coordinated control strategy for the composite braking of motor and electro-hydraulic retarder and the composite braking of mechanical brake, motor and electro hydraulic retarder, a simulation model of electric drive tracked vehicle transmission system is established, making use of real-time simulation tool to verify the strategy. The simulated results show that the dynamic coordinated control strategy can be used to enhance the response speed of total braking torque, and improve the dynamic response characteristics of the vehicle during braking. Key

Experimental Study of High Efficiency and Low Hazard Muzzle Brake for CTA Gun

WANG Jia-gang, YU Yong-gang, ZHOU Liang-liang

2017, 38(5):  1035-1040.  doi:10.3969/j.issn.1000-1093.2017.05.025

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To reduce the hazard of shock wave induced by muzzle brake during the launching process of cased telescoped ammunition (CTA) gun, a high efficiency and low hazard muzzle brake is designed. The high efficiency and low hazard muzzle brake is compared with the traditional muzzle brake through launching experiment. The experimental result indicates that the high efficiency and low hazard muzzle brake can be used to effectively restrict the lateral flow of combustion gas, weaken the shock wave in the flow field greatly, and reduce the intensity of shock wave at the location of launcher by 61.4%, which reduces the harm of shock wave to gunner. Although the intensity of shock wave is slightly enhanced after a silencing bowl is used in the high efficiency and low hazard muzzle brake, but the recoil performance of launching system is significantly improved. Key