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    30 June 2023, Volume 44 Issue 6
    Electronic edition of this issue
    Electronic edition of this issue
    2023, 44(6):  0. 
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    Contents
    Contents
    2023, 44(6):  0. 
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    Autonomous Decision-making and Intelligent Collaboration of UAV Swarms Based on Reinforcement Learning with Sparse Rewards
    LI Chao, WANG Ruixing, HUANG Jianzhong, JIANG Feilong, WEI Xuemei, SUN Yanxin
    2023, 44(6):  1537-1546.  doi:10.12382/bgxb.2022.0177
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    UAV swarms will profoundly shape the pattern of warfare. In order to improve the autonomous decision-making algorithm capability of UAV swarms, the autonomous decision-making method for heterogeneous UAV swarm attack-defense confrontation scenarios is studied. An overview of the design of the UAV swarm confrontation model and the model design of the UAV swarm attack-defense confrontation scenario are carried out. To solve the sparse reward problem which widely exists in the reinforcement learning technology in the autonomous decision-making of the UAV swarm, a reward mechanism setting method based on local reward reshaping is proposed. And then, the prioritized experience replay is superimposed, which effectively improves the sparse reward problem. Finally, the superiority of this method is verified by simulation and demonstration system design. This study will accelerate the network convergence process of the autonomous decision-making algorithm for UAV swarms based on reinforcement learning technology, which is of great significance to the research on autonomous decision-making algorithms of UAV swarms.

    Multi-Dimensional Decision-Making for UAV Air Combat Based on Hierarchical Reinforcement Learning
    ZHANG Jiandong, WANG Dinghan, YANG Qiming, SHI Guoqing, LU Yi, ZHANG Yaozhong
    2023, 44(6):  1547-1563.  doi:10.12382/bgxb.2022.0711
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    To solve the intelligent decision-making problem in the process of UAV air combat, a multi-dimensional decision-making model for UAV intelligent air combat based on the hierarchical reinforcement learning architecture is established, allowing the autonomous decision-making of air combat to be extended from a single-dimensional maneuver decision to a multi-dimensional one including radar switch, active jamming, formation conversion, target detection, target tracking, interference avoidance, weapon selection, etc., so that autonomous decision-making in the main steps of air combat is realized. In order to solve the problems of state-space complexity and low learning efficiency of the decision-making model after the dimension expansion, a meta-strategy group is trained and established with the Soft Actor-Critic algorithm and expert experience, and the traditional Option-Critic algorithm is improved. The strategy termination function is designed and optimized to improve the flexibility of strategy switching and realize seamless multi-dimensional decision-making switching in air combat.. The experimental results show that the proposed method has good countermeasure effectiveness for the multi-dimensional decision-making during the whole process of UAV air combat, which can control the agent to flexibly switch among interference, search, strike, and avoidance strategies according to different battlefield situations with the purpose of improving the performance of traditional algorithms and the efficiency of solving complex decision-making processes.

    Collaborative Task Allocation Method for Multi-Target Air-Ground Heterogeneous Unmanned System
    FAN Boyang, ZHAO Gaopeng, BO Yuming, WU Xiang
    2023, 44(6):  1564-1575.  doi:10.12382/bgxb.2022.0095
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    To address the collaborative task allocation problem of air-ground heterogeneous unmanned systems composed of ground unmanned vehicles (UGV) and unmanned aerial vehicles (UAVs) facing large ranges and multiple targets, the task allocation model of air-ground heterogeneous unmanned systems is established with the completion time of the unmanned systems as the optimization goal and the constraints of the UAV launch and recovery, endurance and task sequence taken in account. A task allocation method for multi-target air-ground heterogeneous unmanned systems is proposed, which combines density peak clustering and hybrid particle swarm optimization algorithm (hybrid-PSO) to solve the task allocation problem of air-ground heterogeneous unmanned systems, so as to obtain the global task allocation results that satisfy the constraints. The proposed method is verified by simulation experiments, and the results show that the method can effectively solve the task allocation problem of air-ground heterogeneous unmanned systems in different operational environments.

    Generation of Multi-UAV Four-dimensional Cooperative Attack Route Based on T/S-SAS
    ZHANG Kun, LIU Zekun, HUA Shuai, ZHANG Zhenchong, LI Ke, YU Jingting
    2023, 44(6):  1576-1587.  doi:10.12382/bgxb.2022.0211
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    To address the problem of target attack time coordination and route space coordination of multiple UAVs, a multi-UAV four-dimensional cooperative attack route generation algorithm based on the T/S-SAS (Time/Space Dual Cooperative Sparse A* Search) algorithm is proposed. The flight expansion node model is improved, an algorithm structure based on concurrent expansion is designed, and a cost calculation model for time coordination as well as a multi-UAV anti-collision constraint model are established. Simulations are performed. The results show that the proposed algorithm can enhance the planning efficiency of UAV attack route, shorten the range in coordination time for different drones to reach the target, and solve the anti-collision problem for different UAVs. The multi-UAV cooperative attack route can meet the time/space constraints, allowing the multi-UAV strike performance at cooperative time and the flight route space coordination performance to be improved, and the operational efficiency and capability of multi-UAV cooperative combat to be increased.

    Progress and Prospects of Polarized Skylight Fused Visual SLAM
    XIA Linlin, ZHANG Jingjing, CHU Yan, ZHANG Daochang, SONG Ziwei, CUI Jiashuo, LIU Ruimin
    2023, 44(6):  1588-1601.  doi:10.12382/bgxb.2022.0288
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    The polarized light navigation that imitates the mechanism of polarized light perception of compound eyes is a newly developed technology, which is stable, passive and totally autonomous. The miniaturization and integration of polarization sensors is currently enabling its fusion with low-cost cameras, inertial measurement units (IMU), etc. The solutions for multi-sensor-based simultaneous localization and mapping (SLAM) are firstly reviewed and analyzed. The research progress in polarization navigation sensors and skylight polarization modes are summarized. Then, the polarized light-aided visual-inertial navigation system (VINS) is explored, and this solution is proved to be feasible for outdoor long-term visual SLAM. The challenging problems of polarization imager model that provides directional observation constraint for the whole navigation system are pointed out in terms of outdoor robot operation system (ROS) and graph optimization for reference. The pipeline design of polarized light-aided VINS-Fusion has the technical characteristic of expanding the absolute pose constraint edges of the graph, and further enables the globally consistent navigation trajectory tracking, providing innovative technical supports for autonomous mobile robot navigation and positioning in remote sensing, mapping and military exploration tasks.

    Research Status and Prospect of Hard-Target Penetration Initiation Control Technology
    LIU Weizhao, LI Rong, NIU Lanjie, SHI Kunlin
    2023, 44(6):  1602-1619.  doi:10.12382/bgxb.2022.0102
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    In order to promote the development of hard-target penetration initiation control technology, based on the hard-target penetration initiation control process, the development status of signal perception, signal processing and initiation control methods are reviewed. The theoretical results and numerical simulation results of penetration overload signal composition, warhead-fuze response and time-frequency characteristics are analyzed. The mixed signal processing, feature extraction and enhancement methods are summarized. The research status of new detection devices, filter materials and adaptive algorithm are reviewed. Through comprehensive analysis, the complexity of penetration overload signal and limitations of current initiation control technologies are revealed. In order to meet the development needs of penetration ammunition, it is important to master the change rules of overload under the constrains of projectile structure, target characteristics and penetration conditions, and to study the mechanism and processing method of multi-physical field signals, and composite sensing, information fusion and quick processing methods. The aim is to formulate a model-based initiation control strategy and independently recognize the process of the projectile penetrating a multi-layer hard target, thus forming an initiation control method with wider applications.

    Dynamic Evaluation of Vehicle Camouflage Effect Based on Saliency Characterization in Complex Background
    WANG Dong, GAO Qinhe, HUANG Tong, LIU Zhihao, GAO Lei
    2023, 44(6):  1620-1631.  doi:10.12382/bgxb.2022.0181
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    To meet the requirement of dynamic evaluation of the vehicle camouflage effect in complex landform background, a vehicle camouflage effect evaluation method based on superpixel segmentation and comprehensive saliency characterization was proposed. The method is based on the negative correlation between the saliency of the target in the background and the camouflage effect, the superpixel adjacency model is adopted, and the local saliency and the target saliency are introduced to comprehensively characterize the camouflage effect. Visual features of the vehicle and multi-scale images of the background are selected to construct multidimensional saliency matrix. Effective feature screening is carried out with the methods of complex correlation coefficient and variation coefficient. The entropy weight method is used to calculate the comprehensive saliency to evaluate the camouflage effect. Through verification and analysis of the numerical examples, the proposed method can evaluate the camouflage effect by integrating the complex landform background, vehicle camouflage state and classical salient visual features, and quantitatively analyze the saliency features and advantageous application environment of the vehicle camouflage state. This work aims to provide suggestions for vehicle camouflage design, state application and concealed area selection.

    Experimental Investigation of the Influence of Preset Rudder Angle on Tail-slapping of a Trans-media Vehicle during Water Entry
    LIU Xiyan, YUAN Xulong, LUO Kai, QI Xiaobin
    2023, 44(6):  1632-1642.  doi:10.12382/bgxb.2022.1117
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    In order to study the influence of preset rudder angle on the tail-slapping characteristics of a trans-media vehicle during high-speed water entry, a high-speed water entry experiment platform is built. A experimental model with an internal measurement unit is designed, and the high-speed water entry experiment of the trans-media vehicle with different preset rudder angles at the water entry angle of 20° is carried out. A high-speed camera is used to record the cavity during water entry of the vehicle, and the internal measurement unit is used to measure the motion parameters and surface pressure of the vehicle. The influence of preset rudder angle on the characteristics of cavity development and water entry as well as the surface pressure of the trans-media vehicle during high-speed water entry is analyzed. The experimental results show that: during the process of water entry, the trans-media vehicle goes through the stages of planing movement and tail-slapping, and the normal overload formed by tail-slapping can be up to twice of that caused by the planing; when the water entry distance is about 5 times the length of the vehicle, the cavity closes, and the pressure in the cavity decreases first and then increases before and after the cavity closure; when the cavity is closed, the attached cavity is separated from the main cavity as the preset rudder angle increases; when the preset rudder angle is 10°, the wake flow of the cavity shows the phenomenon of double vortex tube; with the increase of the preset rudder angle, the turn-flat ability of the trans-media vehicle is enhanced, and the climbing efficiency of the vehicle is improved when single-sided tail-slapping occurs.

    True Color Low-Light Image Enhancement Based on Channel-Calibrated Convolution
    HE Jincheng, HAN Yongcheng, ZHANG Wenwen, HE Weiji, CHEN Qian
    2023, 44(6):  1643-1654.  doi:10.12382/bgxb.2022.0204
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    Aiming at the problems of low brightness, low contrast, noise and color distortion of images produced by existing true color night vision cameras, a neural network algorithm based on channel-calibrated convolution is proposed. The upper branch of the channel-calibrated convolution introduces a channel attention block to analyze the features between the RGB channels. This replaces the traditional convolution in the U-Net network, enabling color recovery and the retention of more image information. The Sobel loss function and color loss function are added to the traditional loss function to suppress noise, preserve image details, reduce chromatic aberration, and enhance contrast. An image dataset under real conditions is collected, which improves the processing effect of the actual data. The experimental results show that the algorithm in this paper can simultaneously deal with the brightness, contrast, noise and chromatic aberration of low-light images, and the enhancement effect is better than the existing mainstream algorithms. Compared with the traditional convolutional U-Net network, the novel method reduces the model complexity and improves operating speed, with a 13.71% reduction in computation, a 13.65% reduction in parameters, a 29.20% increase in PSNR, a 7.23% increase in SSIM, and a 10.46% decrease in chromatic aberration. The algorithm in this paper strikes a balance between imaging quality and speed.

    Optimal Configuration of Aircraft Swarm’s Active Localization with One Transmitter and Multiple Receivers
    WANG Weijia, WANG Yubing, TIAN Jin, MAO Zhaojun, DU linlin
    2023, 44(6):  1655-1664.  doi:10.12382/bgxb.2022.0104
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    To address the problems in the application of aircraft swarms in active cooperative localization with one transmitter and multiple receivers, the optimal configuration and the trajectory optimization method for active cooperative localization are studied to further improve the localization accuracy. Firstly, the model of active cooperative localization using one transmitter and multiple receivers is established. Based on this model, the optimal geometric configuration of target localization with different number of receivers is derived based on A-optimality criterion and D-optimality criterion respectively, and the analytical solution of the optimal configuration is analyzed to provide theoretical support for the aircraft swarm’s trajectory optimization. Secondly, the obtained optimal configuration is applied to the aircraft swarm’s trajectory planning and an active localization method based on A/D-optimality criteria is proposed. Through simulation experiments, the accuracy of active localization for the aircraft swarm with one transmitter and multiple receivers after trajectory optimization has been significantly improved, indicating the effectiveness of trajectory optimization in active cooperative localization for aircraft swarms.

    Characteristics of Ignition Start-up Process of Underwater Solid Rocket Motor with the Effect of Nozzle Closure
    WANG Deyou, LI Shipeng, JIN Ge, WANG Ruyao, GUAN Dian, WANG Ningfei
    2023, 44(6):  1665-1676.  doi:10.12382/bgxb.2022.0136
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    To investigate the flow field and working characteristics of the underwater solid rocket motor at the initial stage of ignition, the gas bubble evolution process under the constraint of nozzle closure separation is numerically simulated. Based on the VOF multiphase model and dynamic mesh technique, a numerical model of underwater gas jet with the effect of nozzle closure is established. The transient evolution of gas bubble morphology and the oscillation characteristics of flow field parameters are analyzed. The characteristics and formation mechanism of initial thrust pulsation after ignition at variable depths are revealed. The results show that: at the initial stage of nozzle opening, the pressure difference drives the closure to strongly impact the liquid phase, causing a high pressure zone in the tail wall space and the formation of an initial thrust peak; as the ignition depth increases, the axial growth rate is slower and the length becomes shorter, the gas bubble has neck contraction in advance, and the pulsation characteristics of the flow field parameters and thrust of the motor become stronger; at the initial stage of ignition in deep water, the shock wave near nozzle exit has reciprocating oscillations, and the pressure oscillation in the tail wall space forms multiple fluctuating thrust peaks. It is demonstrated that the unstable motion of shock waves is the leading factor of thrust pulsation.

    Hardware-in-the-loop Simulation Test Method for Detonation Control of Networked Munitions
    LIU Jinyue, GONG Peng, YANG Haowei, LI Huibo, TANG Feixi, GAO Xiang
    2023, 44(6):  1677-1687.  doi:10.12382/bgxb.2022.0213
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    To solve the problems of high cost and poor repeatability of the range test of the detonation control function of networked munitions, a hardware-in-the-loop simulation test method for the dynamic detonation control of networked munitions based on QualNet is proposed. A hardware-in-the-loop interface between the real network and the simulation network is designed. Based on the interface, the real-time data interaction between the physical equipment and the networked munitions simulation model is realized. Then, a dynamic monitoring software of the safety system is developed. Through the software, the command center can control and monitor the status of the munitions node. At the same time, in order to ensure the reliable and real-time transmission of control command and other types of messages, an application layer communication protocol between the monitoring software and the safe detonation control module is defined. The remote arming and detonation control function of the networked munitions as well as the time delay of the hard-in-the-loop interface are tested. The results show that the proposed method is feasible and effective, which has good real-time performance.

    Opportunistic Maintenance Strategy for Complex Two-dimensional Warranty Equipment Considering Failure Correlation
    DONG Enzhi, CHENG Zhonghua, WANG Rongcai, ZHANG Xiaona, ZHANG Yuexing, WU Weiyi, YUE Shuai
    2023, 44(6):  1688-1703.  doi:10.12382/bgxb.2022.0101
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    To address the problem that isolated maintenance to individual components during the warranty period reduces equipment availability and increases equipment warranty costs, the optimal opportunistic maintenance strategy for multi-component systems is explored by combining the characteristics of complex equipment and the current situation of two-dimensional warranty, with the availability of equipment during the warranty period as the main quantitative analysis index. Based on the failure correlation analysis of the multi-component system, the opportunistic maintenance strategy is applied in combination with the preventive maintenance plan of each single component, and the two-dimensional warranty availability model of the multi-component system is established by introducing the reliability threshold at the time of opportunistic maintenance and optimizing the combined preventive maintenance work of each single component. In the case analysis, the genetic algorithm is used to find the optimal opportunistic maintenance strategy for a new armored assault vehicle power system. The results of the comparative analysis show that the opportunistic maintenance strategy increases the power system availability by 10% and reduces the warranty cost by 9.3%, which fully verifies the effectiveness of the strategy and improves the military and economic benefits of equipment maintenance and support. This strategy can provide a scientific basis and quantitative analysis method for the development of the opportunistic maintenance strategy for multi-component systems using two-dimensional warranty service.

    Comprehensive Proton Irradiation and Electric Field Testing System and Method for GaN Devices
    JI Qizheng, LIU Shanghe, WANG Zhihao, YANG Ming, DING Yigang, WANGSizhan, SHEN Zicai, LIU Yuming
    2023, 44(6):  1704-1712.  doi:10.12382/bgxb.2022.1115
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    Based on the proton irradiation damage mechanism and degradation characteristics of GaN devices, and according to the equivalent fitting principle of dose depth distribution, a comprehensive multi-energy proton irradiation testing method equivalent to the proton irradiation environment in geosynchronous orbit is proposed. The charging potential of circuit board materials is calculated for the problem of internal charging in space, and the simulation method and device for electrostatic field and transient electric field used for the simulation of internal charging effect are designed. A comprehensive proton irradiation and electric field testing system is established and preliminary tests are carried out. The test results showed that: the gate source voltage at peak transconductance of GaN devices shifts with the proton fluence. Compared with proton irradiation alone, the characteristic parameters of devices under the combined action of proton and electric field change faster and more significantly, which proves the effectiveness of the proposed testing method and system.

    Effect of Foreign Object Damage on Vibration Fatigue Crack Propagation of Blades
    YANG Shuo, DU Tianwei, ZHANG Xiaopeng, MA Liang, ZHANG Guichang
    2023, 44(6):  1713-1721.  doi:10.12382/bgxb.2022.0109
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    In order to study the effect of foreign object damage (FOD) on the fatigue crack propagation of aero-engine blades, using the drop weight impact testing equipment, the FOD simulation test and vibration fatigue test of TC4 titanium alloy specimens were carried out under different impact energies. The relationship between the crack length and fatigue life of the damaged specimens was obtained, and the parameters of fatigue fracture crack morphology were fitted to establish a fatigue crack growth prediction and calculation model. The results showed that: The depth and width of the notch decreased nonlinearly with the decrease of impact energy; when the impact energy is large, the fatigue crack propagates first along the bending microcrack and then along the straight line; when the impact energy is small, the fatigue crack of the specimen keeps linear propagation; the crack initiation life is related to both impact energy and stress level.

    Test Method for Anti-overload Performance of Explosives
    ZHOU Lin, NI Lei, LI Dongwei, ZHANG Xiangrong, LIU Haiqing, JIANG Tao, ZHU Yingzhong
    2023, 44(6):  1722-1732.  doi:10.12382/bgxb.2022.0074
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    The test and characterization of the anti-overload performance of the explosives are important basis for the selection of penetrating warhead charge. Based on the single-degree-of-freedom forced vibration model, a testing device for the anti-overload performance of explosives is set up, the mechanical environment and deformation characteristics of explosive charges in the process of warhead penetration are simulated. Then we propose a method for characterizing the anti-overload performance, which is the explosive charge ignition criterion σ ·dσ(σ and σ · are stress and stress rate respectively), and obtain a method for characterizing overload resistance of explosives. The device is used to test the anti-overload performance of three typical DNAN-based insensitive penetrating melt cast explosives, and obtain that their ignition thresholds are 1.8GPa2/ms, 2.2GPa2/ms and 3.3GPa2/ms. Then, the flat-nosed projectile penetration test is employed to verify the anti-overload performance of the above three explosives. The results show that the anti-overload performance test and the flat-nosed projectile penetration test deliver consistent results, indicating that the test method and the device for the anti-overload performance of explosives are scientifically effective in selecting penetrating warhead charges.

    Theoretical Model of Drilling Force Considering Geometrical Parameters of Chamfered Edge of Spade Drill
    WANG Guilin, YU Aibing, ZOU Pian, LI Yi, LI Kefan, WU Senkai
    2023, 44(6):  1733-1743.  doi:10.12382/bgxb.2022.0753
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    To provide reference for the design, development and application of the chamfered edge of the spade drill, the drilling force model of the spade drill considering the geometric parameters of the chamfered edge was established. Based on the orthogonal cutting theory, the geometric coefficient of the workpiece material deformation due to extrusion of the chamfered edge was introduced. The tangential force and normal force models of the chamfered spade drill relative to the direction of the main cutting edge were established. The axial force and torque of the spade drill were calculated according to the actual machining of its cutting edge. Considering the influence of the chip-split grooves on the drilling force of the spade drill, the deformation coefficient was used instead of shear angle and friction coefficient. The finite elements were employed to simulate the spade drilling process. The drilling force of the spade drill was tested experimentally. The axial force and torque of the spade drill were obtained. The drilling force of the spade drill with chamfered edge was compared with the drilling force of the ool with sharp cutting-edge. The results show that: the theoretical formula of drilling force established is suitable for calculating the axial force and torque of spade drills with chamfered edges; the influence law of the geometric parameters of the chamfer edge to the drilling force of the spade drill was obtained; when designing the chamfered edge of spade drills, the chamfer width of the spade drill should be 0.1mm, and the chamfer angle should be 10° or 30° to obtain a low drilling force.

    Anti-Frequency Sweeping Jamming Method for FM Fuze Using Sliding Multi-cycle FFT
    ZHOU Wen, HAO Xinhong, DONG Erwa, CHEN Yanjun
    2023, 44(6):  1744-1753.  doi:10.12382/bgxb.2022.0119
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    This study proposes a sliding multi-cycle fast Fourier transform (FFT) processing method to address the problem of poor performance of the FFT harmonic envelope extraction method used in FM fuze under frequency sweeping jamming conditions. The proposed method aims to achieve effective interference suppression by coherently accumulating echo energy through multi-period FFT processing. The processing data is updated by sliding between adjacent processing windows, and the difference frequency harmonic envelope corresponding to the predetermined blast height is further extracted for threshold judgment. The simulated and measured results show that compared with traditional single-cycle FFT processing method, the new method can effectively extract the target harmonic envelope characteristics under frequency sweeping jamming, significantly improve the peak-to-side lobe ratio, and enhance the anti-frequency sweeping jamming performance of FM fuze.

    Basic Theory of Loading Liner With Electromagnetic Energy and Explosives
    DOU Jianhao, JIA Xin, LIANG Zhengfeng, HUANG Zhengxiang, XUE Biao
    2023, 44(6):  1754-1763.  doi:10.12382/bgxb.2022.0120
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    To improve the explosive’s energy utilization rate of the shaped charge jet, a principle structure in which electromagnetic energy and explosive are combined to load the liner is proposed considering the principles of the liner loaded by electromagnetic force and magnetic flux compression generator. Combined loading is divided into two stages: in the first stage, the capacitor discharge and the initial magnetic flux is formed in the magnetic flux compression generator; in the second stage, Explosive 1 detonates, which compresses the magnetic field and increases the current, and at the same time, the detonation wave propagates to the liner to detonate Explosive 2. The electromagnetic force and detonation pressure jointly crush the liner. Combined with the explosive detonation theory, traditional PER theory of jet formaton and electromagnetic loading characteristics, a theoretical model of jet formation of a liner under combined electromagnetic and explosive loading is established. Then, the jet formation of ϕ56mm shaped charge under the combined loading structure is calculated by the theoretical model, and the influence of the combined loading sequence on jet forming is analyzed by theoretical calculation. The computational results show that the combined electromagnetic and explosive loading can increase the velocity and kinetic energy of the shaped jet, improve the explosive utilization rate of the jet, and optimize the combined loading sequence, which will further improve the jet velocity and kinetic energy. The kinetic energy of the jet under combined loading is 34.5% higher than that of the traditional shaped charge, and the energy utilization rate of explosive is increased by 36%.

    An Automatic Detection Algorithm Based on Wideband Spatial Spectrum of Passive Sonar
    LIU Song, YAO Zhixiang, LU Daiqiang, YUAN Jun
    2023, 44(6):  1764-1774.  doi:10.12382/bgxb.2022.0170
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    In passive sonar boardband target detection, detection based on the fixed threshold cannot adapt to the fluctuating background, and it is easy to detect sidelobes or miss weak targets when detecting strong and weak targets coexisting in the scenario. In addition, the targets occupying multiple beams in the detection results can easily generate beam selection bias for accurate direction finding. To solve these problems, the broadband spatial spectrum is used as the test statistic, and the sorted truncation average algorithm, local peak detection and beam interpolation algorithm are combined. Through theoretical and Monte Carlo experiments, the parameters affecting the estimated threshold value are analyzed, and an automatic parameter selection scheme is designed. A detection threshold adaptive method and an integrated scheme of automatic detection and accurate direction finding are developed. The simulations and sea trials have verified the effectiveness of the proposed algorithm and have strong engineering application value.

    Bond Space Expression of Bending Vibration in Timoshenko Beam and Its Application in Muzzle Disturbance Analysis
    LIN Shengye, WANG Maosen, XIE Yangyang, LI Yong, DAI Jinsong
    2023, 44(6):  1775-1783.  doi:10.12382/bgxb.2022.0175
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    In order to accurately simulate the dynamic behavior of complex beam system, a dynamic model for the Timoshenko beam is established based on the bond space theory, and the method to analyze the natural frequency is presented. The space vectors of effort, flow, momentum, and displacement for the beam unit are defined, and the state equations expressed in momentum space vectors, displacement space vectors, and their first derivatives are derived. Then, the natural frequencies and corresponding mode shapes of the bending beam are obtained by directly solving the eigenvalue problem. The natural frequencies of the free beam, calculated using the proposed bond space approach, match well with the analytical method. On this basis, the proposed model for the bending beam is used to extend the traditional launching system of the automatic gun. The calculated muzzle disturbance aligns well with the firing experiment, indicating that the proposed method is valid. This study provides a new method for the dynamic analysis of projectile-barrel coupling systems.

    Dynamic Characteristics of Quasi-Zero Stiffness Vibration Isolation System with Magnetic Rings
    LI Zhanlong, ZHANG Zheng, JIANG Wenwen, LIU Qi, REN Zhizhao, WANG Yao, SONG Yong
    2023, 44(6):  1784-1794.  doi:10.12382/bgxb.2022.0194
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    Due to the complexity and changeability of the operational and driving environment of special vehicles, personnel and large onboard precision equipment are often exposed to the low-frequency and large-amplitude vibration environment, which directly affects the operational efficiency, even endangers personnel safety and causes serious equipment failure. In order to effectively isolate its low-frequency vibrations, a quasi-zero-stiffness vibration isolation system with magnetic rings is developed, and its system stiffness characteristics and vibration isolation characteristics are studied theoretically and experimentally. Based on the magnetoelectric theory and stiffness coupling theory, the theoretical models of positive and negative stiffness are established and the equivalent stiffness of the system is obtained, and its stiffness mechanism and parameter characteristics are analyzed. The nonlinear dynamic model of the quasi-zero stiffness vibration isolation system is further developed, and the nonlinear dynamic equations of the system are solved by the harmonic balance method and the Newton-Raphson iterative method, its vibration isolation characteristics are analyzed and evaluated, and an experimental bench is built for verification. The results show that: the negative stiffness mechanism has obvious negative stiffness effect and can produce a wider quasi-zero stiffness interval with the positive stiffness system; compared with the linear system, the isolation frequency band of the quasi-zero stiffness vibration isolation system is widened to the low-frequency region by 71.9%, and the resonance peak reduced by 65.7%, the displacement response amplitude decreased by 75%, and the acceleration response amplitude decreased by 80% in the steady-state interval,meaning that the system has a wider vibration isolation frequency band and a larger vibration decay rate.

    Attitude Pursuit GuidanceLaw for Coning Motion Stability of Spinning Missiles
    SONG Jinchao, ZHAO Liangyu
    2023, 44(6):  1795-1808.  doi:10.12382/bgxb.2022.0081
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    To address the problem of coning motion instability of spinning missiles induced by the introduction of the strapdown seeker and attitude pursuit guidance law, the dynamic model of the strapdown seeker in the non-spinning missile coordinate system is derived, and the mathematical model of the attitude pursuit guidance and control system in complex form is established. The response delay of the seeker and the gyro scale-factor error are considered under different spinning rates and damping loop gains. The stability of the spinning missile’s control and guidance system is analyzed, and the range of the corresponding characteristic parameters are solved by numerical methods. The results show that the larger the delay angle of the seeker is, the smaller the upper limit of the guidance loop gain that can stabilize the system is. When the gyro scale-factor error coefficient is greater than 1, the upper limit of the guidance loop gain become larger; when the scale-factor error coefficient is less than 1, the upper limit becomes smaller.

    Plasma Distribution and Its Effect on Electromagnetic Wave Transmission across Vehicles of Varying Sizes
    GAO Tiesuo, JIANG Tao, FU Yang’aoxiao, DING Mingsong, LIU Qingzong, DONG Weizhong, XU Yong, LI Peng
    2023, 44(6):  1809-1819.  doi:10.12382/bgxb.2022.0174
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    Investigating the aero-electromagnetic wave transmission effect is crucial for the assessing and addressing communication blackout issues. This study employs a numerical method to solve the three-dimensional Navier-Stokes equation and wave equation, focusing on the influence of antenna position, electromagnetic wave frequency, and characteristic size of the vehicle on plasma distribution and electromagnetic wave transmission. The results demonstrate that as the sphere radius increases under the same flight conditions, electron number density, plasma sheath thickness, and attenuation of electromagnetic wave also increase. The ionization of NO exhibits the most significant effect on the plasma distribution around antenna. The axial antenna position and electromagnetic wave frequency have a significant influence on the attenuation of electromagnetic wave. Thus, it is feasible to reduce the influence of plasma on electromagnetic wave transmission by increasing the frequency and selecting an appropriate antenna position. During reentry flight along the trajectory, plasma-induced electromagnetic wave attenuation reaches its peak, resulting in a narrower blackout range for high-frequency electromagnetic waves. The numerical results of electron number density and blackout range agree well with flight data under typical flight conditions, demonstrating that this computational code can provide technical support for the design of vehicle electromagnetic communication systems.

    Identification of Mechanical Parameters of Permanent Magnet Servo System Based on Orthogonal Characteristics of Trigonometric Function
    ZHU Qixin, JIANG Chenyan, ZHANG Guoping, ZHU Yonghong
    2023, 44(6):  1820-1828.  doi:10.12382/bgxb.2022.0130
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    To mitigatethe impact of uncertain mechanical parameters on the control performance of apermanent magnet servo system, a method of mechanical parameter identification using the orthogonality of trigonometric functions is proposed. This method applies two mechanical angular velocity commands with different amplitudes but the same angular frequency to the motor.Itdecouples the friction coefficient and moment of inertia of the system through the integration of sine and cosine functions in different intervals, enhancing identification accuracy and eliminating uncertainty. The effect of load torque on the identification results of viscous friction coefficient, Coulomb friction coefficient and moment of inertia is investigated. At the same time, the load torque is observed by using the mechanical parameter values obtained from the identification, and the corresponding feed-forward compensation is performed for the friction torque and load torque of the system. The simulation and experimental results have verified the effectiveness of the method, with a mechanical parameter identification error of about 1%.The control performance of the speed loop is improved to a certain extent after the feed-forward compensation.

    Study and Validation of Resistance Torque Characteristics of Hydro-Mechanical Comprehensive Transmission Device under Low Temperature Conditions
    XU Baorong, ZHANG Jinbao, YAO Ligang, ZOU Tiangang, WAN Li
    2023, 44(6):  1829-1836.  doi:10.12382/bgxb.2022.0182
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    To address the challenge of fast starting of the hydro-mechanical comprehensive transmission device (HMCTD) in low temperature conditions, the transmission characteristics should be tested within a low-temperature range. This study focuses on the resistance torque characteristics of the HMCTD and a single rotating part, both subjected to low-temperature conditions, through running resistance torque characteristic test and flow field analysis. The results show that the resistance torque of the HMCTD decreases with increasing input rotating speed, which is further validated through the single rotating part test. By comparing the flow field at different temperatures, it is concluded that the non-Newtonian behavior of the oil plays a significant role.

    UAV Swarm Tracking Method Based on Wide-Area Deployment of Intelligent Reflecting Surfaces
    ZHENG Lei, CHEN Zhimin, JIA Yuxuan
    2023, 44(6):  1837-1845.  doi:10.12382/bgxb.2022.0217
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    Unmanned Aerial Vehicles (UAVs) play an important role in both civil and military domains. However, their small size, large quantity, and high speed pose significant security threats to national defense. Ensuring low-altitude safety requires effective tracking and locating of UAVs. A cost-effective target tracking method is thus proposed for tracking multiple targets. By deploying low-cost intelligent reflectors across a wide area, data fusion of multiple targets is performed. An improved data association method is proposed. Through feature-assisted fuzzy data association, a part of historical data is used as the feature threshold to screen the optimal observation data, and the measured data that is closest to the real value is obtained. Finally, Kalman filter is used for state estimation to realize the tracking of multiple targets with low cost and high precision. The performance of the proposed method is compared with that of the traditional probability density data association algorithm. The results show that the proposed algorithm achieves smaller root mean square error in position and speed, with a tracking accuracy of around 1.7m, while the traditional algorithm is about 6.6m. Experimental results verify that the proposed method can effectively improve the target association accuracy and tracking performance.

    Design Technology of Radio Frequency Stealth Anti-sorting Signal Based on Cosine-exponential Nonlinear Chaotic Mapping
    JIA Jinwei, HAN Zhuangzhi, LIU Limin, XIE Hui
    2023, 44(6):  1846-1857.  doi:10.12382/bgxb.2022.0201
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    Radio frequency (RF) stealth is one of the research hotspots in radar electronic countermeasures. Anti-sorting signal is one of the main RF stealth signals. The design principle of anti-sorting signals is studied in this paper. After fully considering the tolerance limit of sorting algorithms, a novel method for generating strong random and wide interval PRI values using cosine-exponential modulation is proposed. Simulations on randomness, complexity and balance verify the performance of the proposed chaotic mapping. The anti-sorting ability of the signal is simulated. The results show that the signal designed in this paper exhibits good separation resistance.

    Capacitance Variation of High-Voltage Multilayer Ceramic Capacitors Under Uniaxial Static Pressure
    LIU Bo, YANG He, ZHAO Hui, WU Xuexing, LI Huamei, CHENG Xiangli
    2023, 44(6):  1858-1866.  doi:10.12382/bgxb.2022.0103
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    In view of the capacitance drift of the high-voltage ceramic capacitor under external force, it is proposed that the main reason for the capacitance change of the ceramic capacitor under external force is the change of dielectric properties of the material, rather than the change of capacitance spacing. For the application scenarios of the high-voltage capacitor, the change of the dielectric properties of dielectric materials under external force under certain field strengths is analyzed by the theoretical model of phenomenological thermodynamics. Tensile stress increases the dielectric constant of materials, and compressive stress decreases the dielectric constant of materials. The results of further uniaxial tests and finite element simulations show that: the pressure parallel to the inner electrode produce tensile stress, leading to the increase of the dielectric constant and rising capacitance of the dielectric material; the pressure perpendicular to the inner electrode causes the dielectric material to produce compressive stress, thus reducing the dielectric constant of the material as well as the capacitance. The research results prove that the theoretical model of phenomenological thermodynamics can be used to analyze the capacitance drift of the ceramic capacitor under external force, which may provide important guidance for the adaptability analysis and design of high-voltage ceramic capacitors under more complex environmental conditions.