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    31 December 2020, Volume 41 Issue 12
    Contents
    Contents
    2020, 41(12):  0. 
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    Paper
    Matching Design Method of Tandem EFP for Anti-explosive Reactive Armor
    MEN Jianbing, NIE Yuan, JIANG Jianwei, WANG Shuyou, FENG Gaopeng
    2020, 41(12):  2369-2378.  doi:10.3969/j.issn.1000-1093.2020.12.001
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    The theoretical conditions of detonation capability, separation timing and penetration ability of tandem EFP were proposed for the design of tandem explosively formed projectile (EFP) used for anti-explosive reactive armor (ERA). The ERA detonation criterion, EFP velocity decay theory and penetration theory are used to analyze the influences of shape, mass ratio and velocity gradient on detonation capability, separation timing and penetration ability. For the typical ERA of which interference time τe is less than or equal to 1 500 μs, the necessary conditions of the tandem EFP forming characteristics for distance H≤1 000 ( is charge diameter) are obtained, where 1) for the shape of sphericity-rod combination, the front and rear EFP diameter ratio df/dr≤1.09, the ratio of front EFP mass to total mass is 0.17f/m≤0.40, and the front and rear EFP velocity gradient Δv is larger than or equal to 150 m/s; 2) for the shape of rod-rod combination, df/dr≤1.09,0.20≤mf/m≤0.65,Δv≥166 m/s. An EFP warhead that could form the sphericity-rod tandem EFP was designed and processed. The countering ERA linkage experiment was carried out. The process of EFP separating flight, front EFP detonating ERA, and rear EFP penetrating into target were observed by using the high speed photographic system. The experiments verified the correctness of the theory and the necessary conditions.
    Driver Control Behavior Model for Tracked Vehicle with Stepped Steering Mechanism
    WANG Boyang, GONG Jianwei, XIONG Guangming, ZHANG Ruizeng, CHEN Huiyan, XI Junqiang
    2020, 41(12):  2379-2388.  doi:10.3969/j.issn.1000-1093.2020.12.002
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    For the representation of driving skills at the control level of tracked vehicle with stepped steering mechanism, a driver control behavior model based on control primitive sequence is proposed by utilizing a large amount of collected real driving data. The control primitives are characterized by Gaussian mixture models, and the digraph is applied to complete the extraction and category identification of the driver control primitives sequence. According to the recognition results of different types of control primitive sequence, the driving data is regrouped, and the hidden Markov model-Gaussian mixture model is used to train the driver control behavior model for each type of sequence. The results show that the extracted control primitive sequence can not only represent the driver's steering control primitives switching behavior, but also realize the reasonable division of the trajectory primitive types. Within the predicted time domain corresponding to a given desired trajectory, the proposed model can predict driver control behavior with an average deviation of 4.2% under certain conditions.
    Fractal Construction Method of 2D Road Roughness
    ZHANG Baozhen, WANG Hanping, ZHANG Zhe, CHENG Mengwen
    2020, 41(12):  2389-2396.  doi:10.3969/j.issn.1000-1093.2020.12.003
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    Accurate road roughness model is the key to the simulation research on vehicle dynamic performance. Based on the Weierstrass-Mandelbrot(W-M) function and the definitions of power spectral density(PSD) and coherence function,the analytic coherence relation of the phase angles in the components of fractal model for the left and right wheels is derived. The 2D road roughness fractal models which considers on the phase angle coherence and the Cholesky decomposition of PSD matrix of road roughness are established, respectively,by combining with W-M fractal function and the Cholesky decomposition of PSD matrix of road roughness with different wheelmarks.Theoretical research shows that the road simulation method based on W-M fractal function is equivalent to the harmonic superposition method for γ→1.The fractal model based on the Cholesky decomposition of PSD matrix of road roughness is a universal model,and the fractal model based on the coherence of phase angle is a special case of the above model. Simulated results show that the auto-PSDs of the two models are in good agreement with the corresponding reference PSD,and the accuracy and credibility of the two models are verified consequently for γ→1.
    Mining Association Rules of Tank Driving Simulation Training Based on Bidirectional Concept Lattice
    DENG Qing, XUE Qing, GAO Heng, ZHAI Kai
    2020, 41(12):  2397-2407.  doi:10.3969/j.issn.1000-1093.2020.12.004
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    Training by tank driving simulator is an important way of improving the operating skill of equipment. The statistical analysis method is difficultly used to find the knowledge and rules from the complex training data in simulation training. A mining method of association rules based on bidirectional concept lattice is proposed to analyze the simulation training results of tank driving. The original data table is transformed into single value formal background by using Boolean matrix operation to complete the multiple value data processing of tank driving simulation training. Connotative rank and denotative rank are defined to search the concept nodes from the top and bottom of concept lattice, and the redundant nodes are reduced by combining the support thresholds. Post rule is designed as constraint condition to filter the irrelevant frequent item set, and extract the association rules that meet the mining target of users. The experimental results show that the association rules mining method based on bidirectional concept lattice has obvious advantages in run time and generating frequent item set. It is applied to analyze the training results of a tank driving simulator to extract the valuable reduction association rules, which further verifies the feasibility and effectiveness of the method.
    Optimization on the Position Distribution and Attitude of Electromagnetic Emission Magnetic Probe Array
    WANG Zhenchun, ZHANG Yuting, BAO Zhiyong, LIU Fucai, ZHAN Zaiji
    2020, 41(12):  2408-2416.  doi:10.3969/j.issn.1000-1093.2020.12.005
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    A calculation method for position distribution and installation attitude of magnetic probe array is proposed to obtain the armature velocity at any time in the interior ballistics of electromagnetic launch system accurately. The position distribution of magnetic probe array is determined by Douglas-Peucker algorithm. A mathematical model is established for the induced voltage of magnetic probe and the physical parameters such as installation position, track current, armature speed and displacement, and the influence of the attitude of magnetic probe on the speed measurement accuracy is studied. The installation method of the armature magnetic probe is adopted. The influences of installation mode, installation height and installation depth of magnetic probe array on the measurement accuracy of magnetic probe array were studied. The results show that the theoretical relative error of exit velocity of armature measured by the magnetic probe array is within 2‰, and the theoretical relative error of the internal ballistic armature velocity curve is within 5‰. The installation position and attitude of the magnetic probe array are tested and verified. The improved magnetic probe array has high measurement accuracy. When the armature exit velocity is 700-800 m/s, the measured average relative error of magnetic probe is 2.25%.
    Drainage Characteristics of Circumferential Multi-strand Wall Combustion Gas Jets in a Liquid-filled Circular Tube
    HU Yubo, YU Yonggang
    2020, 41(12):  2417-2423.  doi:10.3969/j.issn.1000-1093.2020.12.006
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    Launching mode,which achieves the same effect as launching in the air by opening several grooves on the inner wall of barrel to guide a part of the combustion gas for real-time drainage, is proposed for exploring the underwater gun fire at low-resistance and its working principle.A three-dimensional unsteady two-phase flow model for the multiple gas jets in the liquid tube is established. The interaction process of gas-liquid in 30mm liquid-filled circular tubes was numerically simulated.The results show that the multiple gas jets converge along the circumferential direction during the expansion process,and then cooperate to discharge the liquid near the wall.Finally,the multiple gas jets converge radially and form a columnar gas curtain. Axial expansion speed of multiple gas jets in the circular tube decays briefly and rapidly first and then changes from fluctuating rise to nonlinear rise.In the near-field of the orifices,the gas area fraction of each section increases gradually with fluctuating. In the far-field of the orifices, the gas area fraction of each section increases rapidly when the gas jets extend to a certain section, and then it rises slowly with fluctuating. The volume fraction of gas in the water-filled circular tube increases non-linearly, and the drainage effect is good.
    Dynamic Unbalance Impulse Charecteristics of a Light Recoilless Rifle
    PANG Chunqiao, TAO Gang, LI Zhao, WEN Peng, REN Baoxiang, LI Zhiyu
    2020, 41(12):  2424-2431.  doi:10.3969/j.issn.1000-1093.2020.12.007
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    A light recoilless rifle was tested experimentally to deeply explore the influence of a period after an aftereffect period on dynamic unbalance impulse of light recoilless rifle. A relevant mathematical model is established based on the analysis of the test results and the motion stability theory of vibration system. The test and calculated results of the model were analyzed. The results show that there is a period after an aftereffect period in the launching process of light recoilless rifle. In the a period after an aftereffect period of light recoilless rifle, the motion stability theory of vibration system can be used to study the mechanism of the influence of residual propellant gas on the dynamic unbalance impulse of launcher. Under the condition of low temperature,the propellant combustion is insufficient,which may lead to the forward moving of the launcher.
    Wake Flow Field Characteristics of Base-bleed Projectiles with Different Nozzle Structures under Transient Depressurization
    ZHOU Shupei, YU Yonggang
    2020, 41(12):  2432-2443.  doi:10.3969/j.issn.1000-1093.2020.12.008
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    The improved advection upstream splitting method (AUSM+) scheme and the shear stress transport k-ω turbulence model are used to solve the two-dimensional axisymmetric Navier-Stokes equations for investigating the effects of different nozzle structures on the wake flow field characteristics of base-bleed projectile under transient depressurization during launching from muzzle. The structures of wake flow filed and the characteristic parameters of base bleed projectiles with annular and circular nozzles were obtained by numerical simulation. The wake flow field characteristics of base-bleed projectiles with different nozzle sizes were compared and analyzed. Calculated results show that the wake flow field at circular nozzle develops from a highly under-expanded jet to a subsonic jet during transient depressurization. In the case of annular nozzle,a highly under-expanded annular jet is extruded to be a central jet on the centerline,and then develops to a subsonic annular jet,in which an expansion wave at the corner of boattail is weakened effectively and the streamline is smoother in the end of depressurization process.The average static pressure and average static temperature at the base of the annular nozzle are higher than those at the circular nozzle,and the effect of drag reduction is better. Jet size has little effect on the base flow field at the end of the depressurization process,but the depressurization rate is higher with the increase in exhaust area ratio,and the rate of pressure rise becomes slower.
    A Small Sample Assessment Method for Firing Reliability of Explosive Initiator Based on the Mean of Sensitivity Distribution
    CHENG Li, DONG Haiping, MU Huina, WEN Yuquan, ZHANG Haoyu, WANG Jingcheng
    2020, 41(12):  2444-2450.  doi:10.3969/j.issn.1000-1093.2020.12.009
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    When the parametric methods are used to estimate the firing reliability of explosive initiator, the bias in estimation of the standard deviation often makes the evaluated results excessive. When the nonparametric methods are used to estimate the firing reliability of explosive initiator,the test sample size is usually large. A small sample reliability assessment method for firing reliability of explosive initiator based on the mean of sensitivity distribution is proposed by using the stress-strain interference model and combining the parametric methods with the nonparametric methods. The proposed method only uses the mean of sensitivity distribution to convert the verification test at the working stimulus to the verification test at the low stimulus at a constant confidence level,thereby greatly reducing the test sample size. The large sample run-down method and the proposed small sample method are used to conduct the comparative tests on a certain type of stab detonator and a certain type of fuse head. The result shows that the reliability evaluation results of the two methods are consistent. The proposed assessment method is reasonable and can be applied to the reliability assessment of mechanical and electric explosive initiators.
    A Green's Function-based 3D Unsteady Heat-transfer Model for SCB
    SUN Yuan, ZHANG Liang, DENG Youqi, LI Song, ZHANG Qiyuan, ZHANG Wei
    2020, 41(12):  2451-2457.  doi:10.3969/j.issn.1000-1093.2020.12.010
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    To improve the integration of a semiconductor bridge (SCB) with digital circuit, the semiconductor bridge is welded on a printed circuit board (PCB). As the hemispherical heat-transfer model is no longer suitable for the special boundary conditions of this kind of package, a model which can accurately describe its heat-transfer process needs to be established. Green's function is applied to the modeling process, and a cuboid model instead of a sphere one is used so that the boundary conditions are closer to the real situation. Then a 3D unsteady heat-transfer model of semiconductor bridge is established. An infrared temperature measuring experiment is carried out after the semiconductor bridge device is connected with a constant current source, and the heat-transfer model is used to calculate the temperature. Comparison between the calculated value and the experimental data shows that the maximum temperature error is less than 4 ℃, and the distribution and rising trend of the temperature are also consistent. This result shows that the model can accurately represent the unsteady heat-transfer process of semiconductor bridge device packaged by a PCB.
    Metal Accelerating Ability of Castable CL-20-based PBX
    WU Yachen, SHEN Chen, SUN Xiaole, JIAO Qingjie, LIU Hailun, YAN Shi
    2020, 41(12):  2458-2465.  doi:10.3969/j.issn.1000-1093.2020.12.011
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    A cast CL-20-based explosive, named GWL, with the ratio of 84% CL-20,11% HTPB and 5% Al-Zn alloy powder was prepared to study the metal accelerating characteristics of castable Cl-20-based composite explosive. The density, detonation speed, detonation pressure, mechanical sensitivity, and three insensitivity characteristics , including fast firing, slow firing and bullet impact of GWL, were tested. The results show that the density of GWL is 1.78 g/cm3, the detonation velocity is 8 750 m/s, the detonation pressure is 33.21 GPa, the reaction level of insensitivity test is combustion, and the mechanical sensitivity also meets the requirements of explosives. The accelerating ability of GWL explosive specimen was tested by a 50 mm standard cylinder test. The test results show that the expension speed of GWL explosive specimen driving the cylinder at 41 mm characteristic point is 1 730 m/s. The cylinder test process is numerically simulated and calculated using the finite element analysis software Autodyn. The JWL equation of state of GWL explosive was obtained by comparing the test results with the numerically simulated results. A control group named GC with the ratio of 89% CL-20 and 11% HTPB was prepared. The mechanical sensitivity and explosive driving ability of GC were tested under the same experimental conditions. The results show that the accelerating abilities of GC and GWL are the same, but the mechanical sensitivity of GC is higher than that of GWL. At last, the accelerating abilities of GWL, C-1 and LX-14 explosives are studied by using AUTODYN software. The results show that the final velocity of GWL is 2.6% higher than that of LX-14. It is a new type of CL-20 based cast explosive with high energy and low sensitivity.
    Real-time Computing of Air-to-air Missile Multiple Capture Zones Based on Deep Learning
    YAN Mengda, YANG Rennong, ZUO Jialiang, HU Dongyuan, YUE Longfei, ZHAO Yu
    2020, 41(12):  2466-2477.  doi:10.3969/j.issn.1000-1093.2020.12.012
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    Modern air combat is becoming more and more complex,and the traditional attack zones can only provide the limits of missile launch,which cannot meet the needs of modern air combat decision-making. For this reason,five types of attack zones, maximun attack zone, 50° attack zone, 90° attack zone, horizontal unescapable attack zone, and minimun attack zone, based on escape angles of enemy aircraft are proposed. The existing solving method of attack zone cannot be used to simultaneously solve the problem of multiple attack zones.A multi-function deep fitting network (MFDFN) is proposed to realize the simultaneous solution of multiple attack zones. Firstly,an improved advance-retreat method is designed,and the sample library of capture zone is obtained through ballistic simulation. According to the characteristics of multi-function fitting network,a training strategy,called “overall pre-training and local fine-tuning”,is presented,by which network is supervised trained.The simulated results show that the MFDFN using the “overall pre-training and local fine-tuning” training strategy reduces the computing time while greatly improving the computing accuracy. The average relative error is about 0.27%,and the average absolute error is about 58.81 meters,which proves that the model is reliable and practical.
    Model Test Method of Reinforcement Effects of Rock Bolts to Caverns under Explosive Plane Wave Loading
    YANG Ziyou, WU Deyi, XU Jingmao
    2020, 41(12):  2478-2485.  doi:10.3969/j.issn.1000-1093.2020.12.013
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    The cavern unreinforcement and reinforcement effects of two kinds of rock bolts to the caverns under the explosive plane wave loading are studied from four aspects, i.e., surrounding rock stress, circumferential strain and acceleration of cavern wall, and roof-to-floor relative displacement, through antiexplosion model test. The intensity attenuation laws of explosive plane waves along vertical and horizontal directions are analyzed. The differences of the circumferential strain and accelerations of cavern wall,and the roof-to-floor relative displacement are compared for the unreinforced cavern, and the caverns reinforced by the full-length bonded rock bolts and the non-full-length bonded rock bolts. The results indicate that the intensity attenuation speed of explosive plane wave in vertical direction is slower than that in horizontal direction. The acceleration and deformation resistance of the arch roof are the largest and the acceleration of the floor is the smallest in each cavern. Arch foot is a place where the tensile strain is very easy to occur in caverns. The reinforcement of rock bolts can change the tensile deformation of surrounding rock of arch foot to compression deformation. The arch roof and floor of cavern reinforced by the full-length bonded rock bolts produce relatively large accelerations. However, the full-length bonded rock bolts are better than the non-full-length bonded rock bolts in some aspects, such as reducing the deformation of arch, the roof-to-floor relative displacement and the acceleration of side wall.
    Disturbance Rejection and Dynamic Tracking Method for Periscopic Laser Communication Terminal
    ZHANG Min, LI Bo, TENG Yunjie, JIANG Huilin
    2020, 41(12):  2486-2494.  doi:10.3969/j.issn.1000-1093.2020.12.014
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    The tracking accuracy and stability of servo system for the periscope laser communication terminal can be reduced by the torque pulsation of the internal actuator and the external disturbance during the establishment of communication link. In order to improve the anti-interference ability and tracking performance of servo system,the speed smoothness of servo system is improved by lowering the torque fluctuations of performing structure.The stability and dynamic tracking process of the system were tested and analyzed,and the effectiveness of the control strategy was verified through the dynamic tracking experiments of terminal control system. The experimental results show that the combined tracking precision of azimuth axis and elevation axis is within 2 μrad under the condition of platform disturbance with the maximum velocity of 0.131°/s and the maximum acceleration of 0.137°/s2 and 0.329°/s2. The jitter suppression ability and dynamic tracking performance of communication terminal servo system are verified through the experiment.
    Detection Method of VLF Acoustic Signal in Complex Marine Environmental Noise
    MA Shilei, WANG Haiyan, SHEN Xiaohong, HE Ke, DONG Haitao
    2020, 41(12):  2495-2503.  doi:10.3969/j.issn.1000-1093.2020.12.015
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    The detection of very low frequency (VLF) signal in the complex marine environment is studied to detect the submarine targets in the complex marine environment. The Lévy distribution is used to describe the noise in complex marine low-frequency environment, and the logarithmic moment method is used to estimate the distribution parameters of the measured noise. A priori knowledge is provided for the following system parameter selection. And then a stochastic resonance method is proposed to detect the very low-frequency signal in the complex marine environmental noise, and the second-order stochastic resonance method under the Lévy noise is analyzed. The matching parameters of stochastic resonance system under Lévy noise are derived, and a detection system of second-order bistable matching stochastic resonance is established. The simulated results show that the detection performance of the second-order matched stochastic resonance detector is much better than that of the traditional correlation detector. When the false alarm probability is 0.01, the detection probability can reach 0.9. Compared with the correlation detector, the required input signal-to-noise ratio can be reduced by 10 dB. Through the field lake experiment, it was verified that the system can effectively detect the VLF sound signals generated by underwater mobile vehicle.
    Neural Network Observer-based Output Attitude Control of a Towed Underwater Vehicle
    JING Anyan, SHE Huqing
    2020, 41(12):  2504-2513.  doi:10.3969/j.issn.1000-1093.2020.12.016
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    The attitude control of towed underwater vehicles (TUVs) is a challenging problem due to the strong nonlinearity and uncertainty of dynamic model, and unmeasurable external disturbances and angular velocity. An observer-based output compensation controller was designed for a TUV, in which two neural networks are employed to identify the dynamic nonlinear model on-line for the state observer and compensated sliding-mode controller, respectively. And a robust term is added to the observer to suppress additional interference. The adaptive weight updating laws and a projection modification adaptive law are designed for neural networks to ensure the stability of the system. It is proved by the Lyapunov method that the observation and control errors of the system are uniformly and ultimately bounded under certain conditions. Simulated and experimental results show that the designed compensation control system has good adaptability and robustness.
    Adaptive High-order Zero-crossing Detector for Airborne Magnetic Anomaly
    ZHOU Jiaxin, SUN Lei, FAN Long, SHAN Zhichao
    2020, 41(12):  2514-2522.  doi:10.3969/j.issn.1000-1093.2020.12.017
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    Traditional airborne magnetic anomaly detection methods rely on prior knowledge of target signal characteristics or noise statistical characteristics,resulting in poor detection probability and short detection distance.In order to improve the performance of airborne magnetic anomaly detectors,an adaptive magnetic anomaly detection method based on the high-order zero-crossing method is proposed, in which the characteristics of the target signal and the statistical characteristics of noise are considered.The characteristics of target signal and noise are analyzed based on the target signal model of ferromagnetic submarine,the measured high-altitude signal of target,and the measured magnetic noises collected over a long period in stable non-magnetic and complex magnetic environments.The high-order zero-crossing statistic characteristics of target signal and noise are researched.Then the test statistic is proposed based on the first five orders of the high-order zero-crossing sequence of signals,and an adaptive high-order zero-crossing detector suitable for detection in complex environment was designed. Theoretical performance analysis and measured data verification show that the magnetic noises collected in stable non-magnetic and complex magnetic environments are quite different, and the noise cannot be simply regarded as a Gaussian distribution. The high-order zero-crossing characteristics of the ferromagnetic and magnetic noise signals are obviously different, and the first five orders of high-order zero-crossing rate are clearly distinguishable. Under the condition of the same input amplitude signal-to-noise ratio, the amplitude of output signal-to-noise ratio of adaptive high-order zero-crossing detector is greater than 5. The anti-noise capability of the adaptive high-order zero-crossing detector is stronger and has good weak signal detection capacity. The detection performance of adaptive high-order zero-crossing detector is better than that of conventional high-order zero-crossing detector and orthonormal basis functions detector. The adaptive high-order zero-crossing detector is suitable for low signal-to-noise ratio detection.
    Accreditation Method for Integrated Anti-torpedo Combat Simulation System of Suspended Depth Charge
    SUN Huiling, HU Weiwen, SONG Yexin, ZHANG Leixiao, LIU Caixia
    2020, 41(12):  2523-2529.  doi:10.3969/j.issn.1000-1093.2020.12.018
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    A mathematic model of survival probability of navel ships is established for integrated anti-torpedo simulation evaluation and confirmation of suspended depth charge. The sample values of survival probability are calculated from the sample data of interception probability output of simulation system. In view of the characteristics of high dimension and large number of survival probability samples,an idea of applying multiple hypothesis test to simulation system validation is proposed. A power model for evaluating test efficacy and a model for calculating p-value of survival probability samples are established,and the steps to solve the key indicators in the model are given. The important evaluation index values of the simulation system were obtained,and the system was evaluated and confirmed. Research results show that the multiple hypothesis test is more strict for the confirmation of simulation system,and it is better than traditional hypothesis test in controlling the first kind of errors.
    Cooperative Tactical Planning for Multi-UAVs Based on Improved A* Algorithm
    ZHANG Zhe, WU Jian, DAI Jiyang, LI Pinwei
    2020, 41(12):  2530-2539.  doi:10.3969/j.issn.1000-1093.2020.12.019
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    Cooperative operation for multiple unmanned aerial vehicles (UAVs) is an important development trendency of combat mode of future UAVs. A cooperative tactical planning method based on improved A* algorithm is proposed for multi-UAVs. The proposed method is used to enhance the mission execution capability of multi-UAV system, improve the overall combat effectiveness, and achieve the efficient resource allocation and scheduling. An iterative optimization scheme for operational goals at the campaign and tactical levels is presented from the two aspects of offline planning and replanning. A mathematical model of formation cooperative operation is established, which takes the time coordination and collision coordination cost of formation members as variables and obtains the comprehensive formation objective function under multiple constraints. Moreover, an improved A* algorithm is developed to address the formation cooperative combat routes by employing the multi-layer variable step search strategy and the single step search method in complex combat environment. The simulation experiments were performed by using the improved A* algorithm and the traditional A* algorithm. The simulated results show that the tactical planning method can complete the combat task well and the improved A* algorithm can obtain the better routes, which proves the effectiveness of the algorithm.
    Simulation of Inflatable Deployment Characteristics of Folding Airbags for Underwater Unmanned Vehicle
    SUN Pan, LI Bin, WEN Jinpeng, ZHANG Xiaoguang
    2020, 41(12):  2540-2549.  doi:10.3969/j.issn.1000-1093.2020.12.020
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    In order to further understand the inflation and deployment behavior of buoyancy assisted foldable airbag for underwater unmanned vehicle (UUV),the inflation and deployment characteristics of UUV annular foldable airbag are studied. The finite element model of annular folding airbag is established based on the initial matrix method. Based on the control volume method,finite element analysis software LS-DYNA is used to simulate the deployment of folding airbag. The validity of the method is verified by comparing with the ground experiment.Considering the different external pressure effects caused by different water depths,the influences of design parameters, such as inflation pressure, inflation pipe diameter,water depth and environmental heat exchange, on the deployment process of underwater foldable airbag are calculated and analyzed.The results show that the limit working depth increases linearly with the increase in inflation pressure,and the inflation time decreases with the increase in inflation diameter. The heat transfer between the environment and the deployment system mainly occurs between the airbag and the environment.After the airbag and the gas cylinder are inflated and balanced,the time of complete deployment of airbag decreases with the increase in the heat transfer coefficient.
    Compensation for Boundary Position of Mirror in Spin Casting of Bifocal Reflector
    NING Lianshuang, FU Weijie, ZHANG Xinming, ZHANG Xuan
    2020, 41(12):  2550-2560.  doi:10.3969/j.issn.1000-1093.2020.12.021
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    In order to study the radius deviation compensation method for the boundary position of the centrifugal shaped reflector surface of bifocal reflector,the trend of melt movement and the deviation of boundary position in the centrifugal casting of bifocal reflector are studied using simulation analysis and analogy experimental method. The spin casting forming process is simulated and analyzed, and studied by way of analogy experiment. The compensation calculation was conducted for the radius deviation of boundary between the inner and outer reflecting surfaces. The simulated results of the forming process of the bifocal reflector were compared with the results of the forming experiment. The results show that the maximum surface shape errors are 6.5 μm and 7.2 μm,and the radius deviations of boundary positions of inner and outer reflectors are 5.2 μm and 7.1 μm,which proves that the numerical simulation method can predict the trend of melt movement during the forming process of bifocal reflector. Different radii are set for cylindrical thermal insulating wall. The simulations are carried out with three different bifocal reflectors, which were formed at 50 r/min for the outer ring reflecting surface and 90 r/min, 100 r/min and 110 r/min for the inner ring reflecting surface. When the position radii of the thermal insulating wall is set 31.08 mm,30.7 mm and 30.39 mm,the boundary position radius deviations of reflector surface are reduced from 4.358 mm,4.264 mm and 4.199 mm to 2.15 μm,2.40 μm and 5.30 μm,respectively. The deviations radii are micron-sized. So it is verified that the boundary position radius of reflector surface can be compensated by changing the position radius of the thermal insulating wall during the spin casting.
    Air Combat Threat Assessment of Improved CRITIC-LRA and Grey TOPSIS
    HU Tao, WANG Dong, SUN Yao, HUANG Zhenyu, JIANG Longting
    2020, 41(12):  2561-2569.  doi:10.3969/j.issn.1000-1093.2020.12.022
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    In view of the subjectivity of using index weight determination in the process of air combat threat assessment and the neglect of the internal relationship between the indexes,a calculation method of determining the index weight based on an improved criteria importance though intercriteria correlation- linear regression analysis (CRITIC-LRA) is proposed. The Gini coefficient and Kendall correlation coefficient are introduced to improve the CRITIC method and determine the initial weight of indexes in accordance with the defects of CRITIC; the first-order linear regression analysis(LRA) is used to calculate the correlation of evaluation indexes, and the indexes relevance is reduced by decreasing the index weight.In order to overcome the shortcomings of using Euclidean distance as a distance measure in the technique for order performance by similarity to ideal solution (TOPSIS),the weighted grey correlation degree between indexes is used to replace Euclidean distance,and the relative closeness degree is calculated to achieve the target threat ranking. The threat assessment example shows that the proposed method can fully reflect the target threat differentiation and rank the targets.
    Combined Sorting Algorithm for Multi-target Sorting in Joint Firepower Strike
    LIU Hao, XIE Peng, LI Yue
    2020, 41(12):  2570-2578.  doi:10.3969/j.issn.1000-1093.2020.12.023
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    A multi-target combined firepower striking mathematical model is established for target sorting in joint firepower strike. A multi-target combined sorting algorithm based on information flow loop efficiency is designed by comparing and referring to the similar system evaluation algorithm. The system value in the joint firepower strike and the regularity of the firepower strike sorting are studied. The simulation models are designed for the fixed target combination and the dynamic target combination, respectively,and the basic principles of the joint firepower target sorting are proposed and verified. The experimental results show that the multi-target combined sorting based on the information flow loop algorithm meets the target sorting battlefield requirements of the joint firepower strike,and has the universality and applicability in the battlefield.
    Comprehensive Review
    Review of State of the Art of Active Suspension Structure Technology of Tank and Armored Vehicle
    WANG Chao, WANG Guosheng, LI Rui, LIU Qingfeng, CAO Yu
    2020, 41(12):  2579-2592.  doi:10.3969/j.issn.1000-1093.2020.12.024
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    The technical status and the lastest research progress of active suspension structure technology for military vehicles are introduced, and the structure and characteristics of electro-hydraulic and electromechanical active suspensions are introduced in detail. The bottleneck problems of active suspension structure for military vehicles are analyzed from the test results of electro-hydraulic and electromechainical active suspensions. The requirements of military vehicle active suspension for structural performance and the key bottleneck technologies are summarized, which are high power density, high reliability and low hysteresis actuator technology. A clear research idea of new active suspension structure is put forward: the innovative introduction of electro-hydraulic composite actuator can not only avoid the large time delay of electro-hydraulic active suspension and the inertial impact of electromechanical active suspension, but also realize the active suspension control.