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30 June 2024, Volume 45 Issue 6

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Contents

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2024, 45(6):  0. 

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Damage Effect of Thermobaric Warhead with Reactive Casing on Phased-array Radar Antenna

JIAO Xiaolong, XU Yuxin, WU Zongya, ZHOU Tong

2024, 45(6):  1725-1734.  doi:10.12382/bgxb.2023.0895

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The power of a warhead composed of reactive shell and thermobaric explosive and its damage effects on phased-array radar antenna are studied to enhance the destructive effects and provide support for the design of relevant warheads. Two kinds of thermobaric warheads with reactive casing and 20 steel casing, which have the same size, are designed. Damage effect tests are conducted on a simulated phased-array radar antenna target. The fireball temperature, shock wave, and target dielectric rod damage ratio are test and analyzed. The following findings were observed through a comparative analysis: For warheads with the same size and explosive charge, the warhead with reactive casing exhibits a 14.90% increase in the maximum temperature and a 20%-50% increase in the area of fireball above 500℃, as compared to the warhead with steel casing. Additionally, the specific impulse of warhead with reactive casing is always higher than that of warhead with steel casing, resulting in a 15.5% increase in the level of damage to a target at a distance of 8 m. Thermobaric warheads can cause damage to a target through natural fragments and shock waves. The shock wave can induce a widespread disintegration of the dielectric rods. And the linear relationship between specific impulse and the damage degree of target is significant. Specific impulse can be used as a criterion parameter to judge the damage of phased array radar antenna. It can be seen from the test analysis that the specific impulse of shock wave should exceed 142.5Pa·s in order to achieve damage to more than 54.8% of the arrayed units.

Energy Distribution of Shock Wave in Deep Rock Mass Blasting

YANG Jianhua, PENG Chao, YE Zhiwei, LENG Zhendong, WEI Bin

2024, 45(6):  1735-1746.  doi:10.12382/bgxb.2023.0254

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In-situ stress has a significant effect on the distributions of the rock mass stress induced by explosion and the explosion energy. To elucidate the distribution characteristics of explosion energy in deep rock mass, the distribution of rock mass stress under the action of in-situ stress and explosion load is calculated using the superposition principle. Subsequently, the failure characteristics of deep rock mass under shock waves are determined using the rock mass failure criterion. The proportions of shock wave energy that causes blasting cavity expansion, radial crack propagation, and rock mass elastic deformation under different conditions are analyzed. Furthermore, a numerical simulation method is employed to investigate the impact of in-situ stress on the distribution of shock wave energy in the rock mass. The results demonstrate that the characteristics of rock mass, the performance of explosive, and the levels of in-situ stress significantly affect the energy distribution. The proportion of total energy of shock waves transmitted into hard rock (granite) and the proportion of effective energy are smaller than those in soft rock (shale) under high in-situ stress environment. Compared with low-performance explosives, when using high-performance explosives for blasting, the proportion of total energy of shock waves transmitted into granite and the proportion of effective energy are greater. With the increase of in-situ stress, the proportion of shock wave energy for the blasting cavity expansion is basically unchanged, the proportion of shock wave energy for radial crack propagation decreases linearly, and the proportion of shock wave energy for rock mass elastic deformation increases exponentially. The effective energy is relatively small although the proportion of the total energy of shock waves is larger under the higher in-situ stress. The findings can provide a reference for improving the energy distribution of shock wave in deep rock mass blasting and enhancing the blasting effect of rock mass.

A Denoising Method for Complex Background Noise of Infrared Imaging Guidance System Based on Deep Learning and Dual-domain Fusion

LI Ping, ZHOU Yu, CAO Ronggang, LI Fadong, CAO Yuxi, LI Jiawu, ZHANG Anqi

2024, 45(6):  1747-1760.  doi:10.12382/bgxb.2023.0307

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The infrared imaging guidance system is severely affected by harsh operating environments, and the imaging process is accompanied by complex background noise interference, which seriously affects the guidance and tracking accuracy of the system. In order to reduce the impact of composite noise on the infrared imaging effect, a priori setting of noise characteristics based on additive and multiplicative components is proposed based on the analysis of the causes and characteristics of various common noises; further, a denoising method for different types of noise based on deep convolutional neural network is designed according to the dual-domain fusion denoising idea of spatial domain and transform domain. This method introduces a rich gradient flow convolutional module into the UNet++ structure to reduce the gradient information redundancy and enhance the multi-receptive field feature extraction ability. A dimension attention mechanism is proposed to achieve dual-domain noise estimation according to the noise morphology characteristics. The high-order dual-tree complex wavelet transform is introduced as the domain transformation method to improve the recognition ability of noise components at different scales and directions. The effectiveness and superiority of the noise prior setting and dual-domain fusion denoising idea are verified through ablation experiments, and the proposed method demonstrates the excellent denoising ability for various types of noise through comparative experiments. The proposed method achieves the peak signal-to-noise ratio of 29.57 and the structural similarity index of 0.85 for Gaussian noise removal, which is superior to other typical noise suppression methods. For multi-type mixed noise, it achieves the denoising levels of 27.84 and 0.82, respectively. Moreover, the proposed method was validated to possess significant capability in removing the noises from real image.

Online Identification and Adaptive Control Method for Servo Transmission Device in Weapon Station

XIE Xin, ZHENG Jieji, LI Baoyu, YU Bin, FAN Dapeng

2024, 45(6):  1761-1775.  doi:10.12382/bgxb.2023.0342

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The control accuracy and safety of pitch axis servo transmission device in weapon stations may be reduced when the weapon load changes. An adaptive composite control method based on multi-parameter online identification is proposed for the issues above. A model framework for identifying the servo transmission devices with nonlinear transmission clearance, motor, and load friction is constructed based on the linearization method of symbolic functions. The explicit iterative equations for the identified parameters are derived, and the online parameter identification is achieved using a recursive augmented least squares algorithm. On this basis, a composite control method combining an adaptive proportional integral controller and an adaptive state-augmented Kalman filter is proposed. The experimental results show that the parameter identification method can achieve the accurate online identification of 9 key dynamic parameters of servo transmission devices, with steady-state identification errors not exceeding 10%. The adaptive composite control method reduces the root mean square of the system speed following residual by 28.24%, effectively improving the control accuracy and stability margin of the pitch axis when the weapon load changes.

Aero-engine Compressor Pressure Simulation Method Based on Multi-mode Acceleration and Backstepping Sliding Mode

LIN Zhonglin, WANG Haitao, LIU Wenchao, GAN Jinyu, ZHANG Tianhong, HUANG Feng

2024, 45(6):  1776-1786.  doi:10.12382/bgxb.2023.0354

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In the aero-engine hardware-in-the-loop simulation test, the compressor outlet pressure simulation is an important part. In order to simulate the sudden change of airflow in the process of compressor destabilization, a high-precision pressure simulation system is designed, through which a real pressure signal is generated to provide an accurate pressure excitation for the full authority digital engine control. A multi-mode acceleration switching strategy is proposed according to the characteristics of the switching valve, and the acceleration drive waveform and generation method are designed to combine with the field-programmable gate array module to accurately output the acceleration waveform and improve the opening and closing speeds of switching valve. A seven-mode switching method is designed based on the traditional three-mode and five-mode switching methods. The backstepping sliding mode controller is combined with the seven-mode switching method to improve the control accuracy, and the stability of control system is proven. The test results show that the maximum average overshoot in the steady-state pressure test is 1.25%, and the maximum average steady-state error is 0.016MPa. The average errors in the random step response and sinusoidal tracking tests are less than 0.02MPa. The proposed pressure simulation method can meet the requirements for high-accuracy pressure simulation of aero-engine hardware-in-the-loop simulation tests and achieve the accurate pressure simulation at a low cost.

A Multitask Guidance Algorithm Based on Transfer Learning

LUO Haowen, HE Shaoming, KANG Youwei

2024, 45(6):  1787-1798.  doi:10.12382/bgxb.2023.0082

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For typical aircraft guidance missions, the deep learning algorithm can be used to effectively fit the functional relationship between missile flight state and guidance command. However, when the guidance mission changes, the mapping relationship between them will also change. As a result, a pre-trained model in the current environment cannot directly act on a new environment, and retraining the guidance model requires a large amount of ballistic data and a huge amount of time cost. In order to solve the above problems, a domain adversarial neural network is introduced based on the idea of transfer learning, and a multitask guidance algorithm based on transfer learning is proposed. One task in the source domain containing a large amount of tag data is used to assist two tasks in the target domain containing a small amount of tag data for transfer learning, so as to overcome the environmental difference between pre-training and online control. The key features that are not sensitive to the task environment are extracted by using feature extractor and domain discriminator so that the neural network learn the underlying information shared by each task. In order to improve the prediction accuracy, the bias acceleration predictors for different tasks are designed, respectively. The simulated results show that the multitask guidance algorithm based on transfer learning can predict the acceleration instruction of a missile in different missions.

Infrared and Visible Image Fusion Using Dual-stream Generative Adversarial Network with Multiple Discriminators

WU Lingxiao, KANG Jiayin, JI Yunxiang, MA Hanyan

2024, 45(6):  1799-1812.  doi:10.12382/bgxb.2023.0130

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To address the problem of insufficiently retaining the source information during the process of fusing the infrared and visible images based on the existing methods, an algorithm for fusing the infrared and visible images using dual-stream generative adversarial networks (GAN) with multiple discriminators is improved. The improved GAN-based fusion framework consists of one generator and four discriminators, and utilizes the differential image as the auxiliary information to further improve the performance of the fusion network. The differential imagein the algorithm is not only used as the auxiliary information of source image to guide the generator to focus on the unique information of different modal images, but also used as the real data distribution to assist the differential discriminator in competitively training with the generator. In the improved network model, the generator adopts a dual encoder-single decoder structure, where the encoder aims to extract the features from different modalities mainly via a densely connected structure combined with an attention module, and the decoder is used to reconstruct the fused image based on the concatenated high-dimensional features. The discriminator evaluates whether the input image is the real image or the fusion image, and constrainedly optimizes the generator based on the evaluated results. Experimental results show that, compared with the other algorithms, the improved algorithm achieves better fusion results both in the subjective assessments and in the objective effects evaluated by the quantitative metrics.

Robot Path Planning for Persistent Monitoring Based on Improved Deep Q Networks

WANG Xiaolong, CHEN Yang, HU Mian, LI Xudong

2024, 45(6):  1813-1823.  doi:10.12382/bgxb.2023.0227

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Persistent monitoring refers to the long-term monitoring of road network environment by planning the patrol route of mobile robots in the road network, so as to achieve the purpose of ensuring environmental safety. The sites to be monitored in the environment are usually limited by the maximum allowable monitoring period (revisit period). A fixed monitoring period should not be set for an optimal monitoring path, otherwise, the monitoring process is easy to be destroyed by malicious intruders. To solve the above problems, a robot monitoring path planning algorithm based on improved Deep Q Networks (DQN) is proposed, the decision-making method of DQN is improved, and a monitoring path with high monitoring frequency, good security (ability to prevent intelligent intrusion) and non-fixed period is planned for robot. Simulated and experimental results show that the proposed algorithm can efficiently cover all nodes to be monitored. Compared with the traditional DQN algorithm, the proposed algorithm does not make the monitoring fall into the cyclic path, and enhances the anti-intrusion ability of the persistent monitoring system.

Numerical Simulation of Uniform Extrusion Forming and Die Structure Optimization of Lightweight Empennage-shaped Component Based on Response Surface Method

JIA Jingjing, ZHANG Zhimin, YU Jianmin, XUE Yong, WU Ang

2024, 45(6):  1824-1839.  doi:10.12382/bgxb.2023.0187

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In order to solve the problems of non-uniform metal flow and large anisotropy of mechanical properties in forward extrusion forming of lightweight magnesium alloy empennage-shaped component, a metal reservoir die structure is proposedto regulate the uniform metal flow. Based on Deform-3D finite element simulation, the Box-Behnken response surface method is used to establish the response relationship among the mean square difference of metal flow velocity at the exit of die, the forming load and the structural parameters of metal reservoir by taking the depth of h, the length D₁ of metal reservoir tank wall from the empennage-shaped core cavity, the length D₂ of metal reservoir tank wall from the empennage-shaped cavity, and the angle α between the metal reservoir tank wall and the empennage-shaped cavity as variables. The results of response surface analysis show that the optimal structural parameters of metal reservoir are h=7mm, D₁=13mm, D₂=6mm, and α=11°. The inhomogeneity of metal flow and the anisotropy of mechanical properties are improvedand the empennage-shaped component with dimensions and mechanical properties that meet the requirements are successfully manufactured using the optimized die structure parameters.

Effect of PBX Interface on Hot Spot Formation and Safety under Impact Loading

XIA Quanzhi, WU Yanqing, CHAI Chuanguo, YANG Kun, HUANG Fenglei

2024, 45(6):  1840-1853.  doi:10.12382/bgxb.2023.0122

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The interfacial structure of polymer-bonded explosive (PBX) has a significant effect on the hot spot formation and impact safety. In order to study the ignition response process of PBX under impact condition, a finite element model reflecting the real internal structural characteristics of the PBX is established by digital modeling and vectorization of images. The model considers the heat generated by friction, the temperature rises caused by crystal deformation, and the exothermic reaction. The hot spot formation under PBX impact load is numerically simulated. Hot spot density is introduced as a basis for determining whether material ignition occurs, and the effects of crystal surface roughness and crystal coating defects on the ignition sensitivity and impact safety of PBX are analyzed. The results show that the internal heat of PBX initially comes from frictional heat generation and crystal deformation during impact loading, and when the temperature gradually raises, the heat mainly comes from the exothermic reaction of crystal. The critical hot spot density for material ignition is 0.68mm^-2. Reducing the crystal surface roughness and improving the coating quality of crystal can help to inhibit the formation of hot spots and reduce the material sensitivity, which can improve PBX safety. This work can be used to evaluate the ignition sensitivity and safety of high explosives and guide their production and processing.

Trajectories and Attitudes of a Slender Submarine with Large Amplitude Motions under the Action of Internal Solitary Waves

LIU Xindan, GOU Ying, TENG Bin

2024, 45(6):  1854-1865.  doi:10.12382/bgxb.2023.0313

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The large internal solitary waves inside the ocean may pose a threat to the navigation stability and safety of a submarine. A time-domain solution model for the large motion of the slender submarine structure under the internal solitary waves in two-layer flow is established to explore the motion response characteristics of submarine when encountering the internal solitary waves head-on. The nonlinear forces caused by the coupling of various degrees of freedom motions are considered in the model, the internal solitary wave forces are calculated by Morison equation and Froude-Krylov force, and the static changes caused by the propagation of internal solitary wave are calculated by integrating the static pressure on the surface of submarine. The accuracy of the proposed model is verified by comparing with experimental results of physical models and computational fluid dynamics numerical results, and the motion trajectories and attitudes of SUBOFF submarine at different depths and speeds in two layers of flow are calculated by this model. The numerical results show that, under the action of internal solitary waves, the submarines above and at the density layered interface move along the propagation direction of internal solitary waves, the submarine below the density layered interface moves against the propagation direction of internal isolated waves; Vertically, the submarine will experience a significant drop in depth, and it sinks first and then floats. The submarine shows different trajectories and attitudes at different depths and speeds.

Analysis of Angular Motion and Swerving Response Characteristics of Dual-spinning Two-dimensional Correction Projectile with Canard Layout

LI Hongyun, SHEN Qiang, DENG Zilong

2024, 45(6):  1866-1876.  doi:10.12382/bgxb.2023.0057

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In order to study the dynamic response law of dual-spinning projectile with canard layout in the state of control, the angular motion and swerving response characteristics of it are analyzed theoretically. Based on the seven degrees of freedom rigid body ballistic model, the transient-state and steady-state analytical solutions of the angle of attack of projectile are solved, and the analytical expressions of projectile’s transient-state and steady-state swerving responses are derived. The effects of control command update period, elevation angle, spin rate and initial velocity on swerving response characteristics are explored. The results show that the direction of control force has little influence on the phase shift angle of swerving response. When the update period of control command is short, the transient-state and steady-state solutions of phase shift angle differ greatly at the ballistic apex, and the transverse-longitudinal coupling of projectile is low after using the transient solution correction. With the increase in update period, the transient-state solution of phase shift angle of swerving response gradually approaches to the steady-state solution. In addition, the steady-state solution of phase shift angle decreases with the increase in rotational speed and increases with the increase in projectile velocity. The correctness of the theory is verified by experimental data. This research provides some theoretical basis for the design and analysis of two-dimensional correction control system of dual-spinning projectile with canard layout.

An Improved Multidimensional Parallelepiped Model for Structural Uncertainty Analysis

QIAO Xinzhou, ZHANG Jinrui, FANG Xiurong, LIU Peng

2024, 45(6):  1877-1888.  doi:10.12382/bgxb.2023.0085

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The multidimensional parallelepiped model is a non-probabilistic convex set model that can take into account dependent and independent variables simultaneously. Therefore, it is more suitable for the “multi-source uncertainty” problems in engineering structures. An improved multidimensional parallelepiped model is presented to more reasonably and efficiently quantify the structural uncertainties. An explicit expression for the uncertainty domain of the parallelepiped model is given by defining the correlation angle and marginal intervals of interval variables. A method is further formulated to construct a multidimensional parallelepiped model based on the experimental sample points. The analyzed results of three numerical examples show that the proposed model can better reflect the correlation of interval variables, and has a more compactness and rationality than the traditional multidimensional parallelepiped model.

Artificial Neural Network-based Prediction Model for Damage Effect of Fuel-air Explosive

XU Yongkang, XUE Kun

2024, 45(6):  1889-1905.  doi:10.12382/bgxb.2023.0094

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The prediction of damage range caused by Fuel-air Explosive is fundamental to the study of large-scale damage caused by Fuel-air Explosive weapons. However, the distribution pattern of shock waves after detonation and its dependence on fuel concentration are unknown, which limits the prediction accuracy of damage range. In this study, the minimum free energy method is used to calculate the CJ parameters for the ideal detonation of biphasic cloud fog with liquid fuel present in either droplet or vapor form. The JWL equation of state parameters are obtained through fitting. Subsequently, the peak overpressure caused by ideal detonation of biphasic cloud fog with different concentrations and states is calculated. A proxy model is developed by utilizing an artificial neural network. The proposed model is used to predict the decay law of peak overpressure with respect to the scaled distance for biphasic gas-solid and gas-liquid-solid cloud detonations with concentrations ranging from 0.03 to 0.30kg/m³. The model is also used to predict the variation of damage proportion radius with fuel concentration for different damage levels, obtaining the optimal concentration with the maximum damage proportion radius. The study reveals that the influences of liquid fuel in droplet or vapor form on cloud detonation parameters, JWL equation of state parameters, and shock wave distribution after cloud detonation are relatively weak (<1.5%). Within the fuel concentrations ranging from 0.03 to 0.18kg/m³, the maximum and minimum values of damage proportion radius for damage levels Ⅰ-Ⅲ are differed by 21%, 19%, and 6%, respectively. Thus, the dependence of damage radii on fuel concentration is stronger for damage levels Ⅰ and Ⅱ after cloud burst caused by large explosive structures.

Active Disturbance Rejection Force Synchronization Control for Pump-controlled Multi-link Erection System

ZHU Weilin, YAO Jianyong, LIU Jiahui, LI Lan, ZHANG Jialin

2024, 45(6):  1906-1920.  doi:10.12382/bgxb.2023.0318

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The pump-controlled multi-link erection system has the issues of nonlinearity, model uncertainty and force fighting arising from asynchronous motion., An active disturbance rejection force synchronization control strategy is proposed for such a dual-cylinder erection system. Considering the kinematic characteristics of the multi-link erection mechanism and the pressure-flow dynamics of the closed pump-controlled hydraulic system, a dynamical model of multi-link erection system is established. The system disturbances and model uncertainties are estimated by the extended state observer to compensate for them in the controller design process, while a composite force synchronization control method is integrated to enhance the system to overcome the force fighting caused by unbalance load and external disturbances. Based on Lyapunov theory, the multi-link dual-cylinder erection system can achieve asymptotic tracking and force synchronization performance. Finally, the effectiveness of the proposed active disturbance rejection force synchronization control strategy is verified by the comparative experiments of medium-speed and rapid-speed constant-power erections, and the excellent erection tracking and force synchronization control performance is obtained.

Correlation Method of Acoustic Characteristics of Multiple Targets during Water Entry

LI Yanhe, ZOU Nan, ZHANG Limin, LIU Bing, XIU Xian, WU Zongzheng, FU Keyi

2024, 45(6):  1921-1932.  doi:10.12382/bgxb.2023.0250

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The underwater acoustic signal generated by a target entering the water is complex which can easily cause false alarm and miss due to the impulsive interference in ocean. In addition, it is difficult to correctly correlate the underwater acoustic signals of the same target between different observation nodes when multiple targets enter the water at different intervals. In order to solve the above problems, a multi-target water-entry acoustic signals correlation method is proposed. The detected transient signal is decomposed into the intrinsic mode function (IMF) through empirical mode decomposition, and the characteristics of the frequency spectrum and so on are extracted. The grey relational analysis method and fuzzy C-means clustering algorithm are used to realize the correlation of multi-target water-entry acoustic signals, providing necessary conditions for the subsequent distributed positioning. The simulated results show that the target correlation accuracy of the two methods can reach 98% and 87%, respectively,when the number of target feature parameters is 6, and the target correlation accuracy of the two methods can reach 95% and 87%, respectively, when the number of observation nodes is 7. The simulated results prove the feasibility and effectiveness of the proposed method.

The Influences of Forebody Parameters of Flat-nosed Projectile on Trajectory Stability and Range

XU Yuntao, TAN Dalin, YANG Chao, DAI Yuting, WANG Zhenxiao, ZHOU Peng

2024, 45(6):  1933-1941.  doi:10.12382/bgxb.2023.0236

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The influences of forebody parameters on the trajectory stability and range of supercavitating projectile are studied in the paper. A high efficiency coupling method of flow field and trajectory is established based on modal dynamics, a quantitative evaluation method for the trajectory stability and efficient range of supercavitating projectile during tail-slapping is proposed, and the simulated cavity shape and tail-slapping trajectory are validated. On this basis, the change law of trajectory stability and range of the projectiles with different lengths and diameters of forebody are analyzed. Results show that the trajectory stability increases with the increase in the diameter and length of forebody, and the trajectory instability mode can be divided into direct instability and oscillate instability. With the increase in diameter, the maximum range increases at first and then decreases, the maximum range is 3.8 times of the minimum range in the design domain, which means the forebody parameters have a relatively large influence on the range of projectile.

Overall Load Extrapolation Method Based on Frequency and Extreme Value Extrapolation

GAO Hua, SHAN Chunlai, LIU Jun, ZHANG Fanfan, LIU Pengke

2024, 45(6):  1942-1953.  doi:10.12382/bgxb.2023.0072

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Load extrapolation, as an important technical means for compiling load spectra, is inconvenient to generate the high-precision load spectra to support equipment performance design due to lacking of the comprehensive review of overall load extrapolation method, the insufficient adaptability of solution method for Markov steady-state distribution, and the comparison and selection principles for different nonparametric frequency extrapolation methods. Focusing on the compilation of tank’s load spectrum under high mobility and extreme conditions, the nonparametric extrapolation method based on rain flow matrix and kernel density estimation, the signal reconstruction based on Markov Chain Monte Carlo (MCMC) method, and the Metropolis-Hastings (MH) direct sampling method are used to perform the frequency extrapolation according to the barrel displacement dataset of a tank in motion. Besides, an improved Markov steady-state distribution solution method is proposed for the signal reconstruction method of MCMC. Finally, the proposed overall frequency-extreme load extrapolation method is used to expand the frequency and predict the extreme values of the dataset. The accuracy of overall method is verified based on experimental results. It is shown that the improved Markov steady-state distribution solution method is effective. The MH direct sampling method can be used as a new frequency extrapolation method when the sample length is sufficient and the extrapolation accuracy is not very high. The accuracy of overall frequency-extreme load extrapolation method is relatively high. The principles for selecting frequency extrapolation methods have certain guiding significance for the selection of methods in the process of compiling the load spectra. The research work provides a mature technical route and reference for the high-quality equipment load spectra compiling.

Prediction and Optimization Method of Energy Absorption Characteristics of Thin-walled Metal Circular Pipe Filled with Aluminum Foam

YAN Song, JIANG Yi, DENG Yueguang, WEN Xianghua

2024, 45(6):  1954-1964.  doi:10.12382/bgxb.2023.0366

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In order to improve the energy absorption characteristics of aluminum foam-filled thin-walled metal circular tube and realize high-efficiency structural design, an approximate model of the energy absorption characteristics of aluminum foam-filled aluminum tube under axial impact is established based on the uniform Latin hypercube design method and radial basis neural network, and it is embedded into the genetic algorithm to realize the structural optimization of components. The results show that the goodness of fit of the approximate model based on the radial basis neural network is greater than 0.99, the root mean square error is less than 0.08, and the calculation time of the approximate model is only 0.56% of the numerical calculation. The approximate model can greatly improve the calculation efficiency while ensuring higher accuracy. Through the optimization of the structure of aluminum foam-filled aluminum tube, it is found that the average compression force of aluminum foam-filled aluminum tube can be maximized by increasing the radius and wall thickness of the circular tube and reducing the height, and on the contrary, its peak compression force can be minimized. The multi-objective optimization based on the genetic algorithm significantly improves the energy absorption characteristics of aluminum foam-filled aluminum tube. The research results can provide a reference for the rapid design and optimization of aluminum foam-filled thin-walled metal circular tube.

Principle Error Analysis of Four-light-screen Optical Target with Impact Coordinates Measurement under Oblique Incidence

LI Jing, SUN Zhonghui, NI Jingping, DUAN Chenxi, CUI Changqing

2024, 45(6):  1965-1973.  doi:10.12382/bgxb.2023.0097

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In order to study the distribution law of the principle error of impact coordinate measurement for an obliquely incident projectile, a principle error model of impact coordinate measurement under oblique incidence is established according to the geometric structure of four-light-screen optical target. The distribution law of the principle errors at different impact positions and different incidence angles in the effective detection light-screen plane is studied. The influences on different dispersal radius and different shooting distances on the measurement principle error at the determined shooting position in engineering application are analyzed, and the correction formula for the measurement of impact coordinates is given. The shooting test was carried out. The results show that: the principle error inevitably exists when the flying projectile is obliquely incident, thus the impact coordinate should be corrected. At a certain shooting distance, the larger the gun’s dispersal radius is, the larger the principle error is; when the dispersal radius is determined, the principle error decreases with the increase in shooting distance; under the determination of shooting position, the measurement error of four-light-screen optical target is less than 1mm after using the correction formula.

Optimization Design Method of Complex Equipment System-of-systems Based on Forward Analytical Formula and MOGT Optimization Algorithm

DING Wei, MING Zhenjun, WANG Guoxin, YAN Yan, YU Lei

2024, 45(6):  1974-1990.  doi:10.12382/bgxb.2023.0031

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For the problems of many index variables, strong simulation dependence and being easy to fall into local optimum in the optimization design of complex equipment system-of-systems (CES), an optimization design method of CES based on forward analytical formula and multi-objective game theory (MOGT) optimization algorithm is proposed. In order to improve the interpretability of the CES optimization design, evaluation index systems among task-level, capability-level and equipment-level are constructed. On this basis, the positive mapping relationship between the evaluation performance index and the combat capability is characterized based on the equipment mechanism and utility function, and the weight of each index is calculated by the adjacent priority degree entropy weight method. A multi-objective optimization model is established by using the forward analytical formulas and constraints, and the MOGT optimization algorithm is used to obtain the best optimization results.The air defense scenario in an operation deduction platform is taken as an example for the example evaluation and verification analysis. The results show that the proposed method can realize the solution of the optimal design scheme in the CES, which can significantly improve the design efficiency and reduce the design cost, and provide the basic work for the development demonstration, design evaluation and combat test of the next generation equipment.

A Dynamic Model of Interval Uncertainty of Rotational Chain Shell Magazine

ZHAO Wei, HOU Baolin, YAN Shaojun, BAO Dan, LIN Yubin

2024, 45(6):  1991-2002.  doi:10.12382/bgxb.2023.0379

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For the identification problem with interval uncertain parameters, a double-layer nested identification (DNI) method based on an interval possibility degree transformation model is proposed. By dividing the parameters to be identified into two categories, the first type of deterministic parameters are identified by DNI method, and the interval range of the second type of interval uncertainty parameters is optimized by the DNI-based interval optimization method. The BO-PSO algorithm is chosen as the inner-layer algorithm to improve the efficiency of the nested strategy type method. For the inner layer of DNI method, BO-PSO method is used to calculate the upper and lower bounds of interval, and for the outer layer, ICS method is used to identify the specific parameters. In order to shorten the solving time, an ICS-MK-ELM agent model is proposed. The ICS-MK-ELM agent model overcomes the difficulty of manually adjusting the hyper-parameters of each kernel function, and the prediction precision of the model is obviously higher than those of KELM and MK-ELM. Finally, the DNI method is applied to the parameter identification of the rotational chain shell magazine, which solves the problem of the parameter identification of the chain-type magazine with interval uncertainty. The results of parameter identification show that the DNI method and the interval optimization method based on DNI have higher accuracy and stability.

Assessment of Diesel Engine Valve Performance Degradation Status Based on Synchroextracting Enhanced Generalized S-transform

LIU Zichang, BAI Yongsheng, LI Siyu, ZHANG Kun, LIU Min, JIA Xisheng

2024, 45(6):  2003-2016.  doi:10.12382/bgxb.2023.0363

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The operating status of diesel engine changes with the performance degradation of valve as the valve clearance gradually increases during operation. It is difficult to accurately assessment the performance degradation status of valve by traditional status assessment methods. A diesel engine valve performance degradation status assessment method based on synchroextracting enhanced generalized S-transform (SEEGST) is proposed. The vibration signal reflecting the status of diesel engine is collected by sensors. To solve the problems of low time-frequency resolution and weak energy aggregation in traditional signal time-frequency analysis methods, a SEEGST time-frequency analysis method is proposed based on the synchroextracting algorithm and generalized S-transform to convert the vibration signal into a two-dimensional time-frequency map. MLP-Mixer model is used to extract the time-frequency image features for training,thus realizing the assessment of diesel engine status. The proposed method is compared with five traditional methods, namely SSGST-MLPMixer, GST-MLPMixer, SEEGST-ViT, SEEGST-2DCNN and FFT spectrum-1DCNN, by conducting the valve performance degradation experiment on a diesel engine status monitoring test bench. The experimental results show that the overall assessment accuracy of the proposed method reaches 98.96%, which can be effectively applied to the diesel engine valve performance degradation status assessment and provides a new idea for conducting the diesel engine valve performance degradation status assessment.

Study on Curved Surface Formability of 3D Woven Preform for Ballistic Helmet

ZHANG Changlong, CHEN Li, WANG Jing, JIAO Wei, LI Haitao

2024, 45(6):  2017-2024.  doi:10.12382/bgxb.2023.0334

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Three-dimensional woven preform (3DWP), because of its better formability and significant interlaminar bearing capacity, is expected to achieve the integrated molding of helmet curved surfaced, and reduce the waste of cut and raw materials. Because of the structure characteristics of ballistic helmet with multiple curved surfaces and high curvature, it is important to study the deformation mechanism of 3DWP during curved surface forming for the integrated forming of helmet. The curved surface formability of a layer-to-layer interlock 3DWP with stuffer yarns under high curvature and large deformation is studied systematically. The deformation mechanism and wrinkle defects formation mechanism of 3DWP are described comprehensively from in-plane/inter-layer dimensions and macro/mesoscale. The results indicate that significant in-plane shear deformation of 3DWP can be observed along the 45°direction at the same latitude. The maximum in-plane shear angle of the concave surface is 38°, which is greater than that of the convex surface. The maximum inter-layer shear angles of 3DWP warp and weft rows are 34.83°and 27.76°, respectively. After forming, 3DWP has reached 62° intra-ply shear locking angle, which induces the buckling of yarns microscopically and forms the ridged wrinkles macroscopically. In the wrinkle area, the maximum in-plane shear angle is only 4.8°, and the maximum inter-layer shear angle is 18°. This conclusion has guiding significance for structure selection and forming process of reinforced fabric for ballistic helmet in practical application.

Acoustic Reflection Characteristics and Strength Enhancement Method of Underwater Multigrid Elastic Corner Reflector

LUO Yi, ZHANG Jingzhuo, CHU Zichao, WU Haoran

2024, 45(6):  2025-2033.  doi:10.12382/bgxb.2023.0012

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Single grid corner reflector can only reflect the incident wave in a certain direction. In order to reflect the incident acoustic waves in different directions, it is necessary to construct a multigrid corner reflector and study its acoustic reflection characteristics. Taking the different types of eight-grid corner reflectors as the research object, the scattering acoustics field of underwater multigrid corner reflectors is simulated based on the structure finite element coupled indirect boundary element method. The acoustic reflection performance of different types of multigrid corner reflectors under the condition of different frequencies, materials, thicknesses, and incident angles is analyzed. A method to improve its acoustic reflection ability is proposed from the perspective of convenient engineering application. The consistency between the simulation data and the experimental data is verified through the experiment in a pool under typical conditions. The results show that the target strength of underwater multigrid elastic corner reflector increases with the increase in the incident frequency and tends to be stable; the target strength fluctuates greatly with the change of incident angle, and the target strength values of different types of corner reflectors are greatly different; target strength increases with the increase of plate thickness, but not significantly; the target strength increases obviously with the increase in the side length; and the acoustics reflection performance of multigrid corner reflector made of soft material is better than that of metal corner reflector. Therefore, in order to enhance the acoustic reflection ability of underwater multigrid corner reflector, it is more effective to increase the side length of reflector and select low impedance material.

Blasting Height Control Method of Millimeter Wave Proximity Fuze for Tank Gun Based on Data Setting

CHEN Zhipeng, LI Haojie, YAN Bingqian, ZHANG Chuanhao, QIAO Shixiang, ZHANG He

2024, 45(6):  2034-2043.  doi:10.12382/bgxb.2023.0028

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In order to meet the requirements of striking the personnel, armor, covered and other targets, the millimeter wave proximity fuze for tank gun needs to have a variety of blasting heights to maximize the projectile damage efficiency. It is difficult to meet the multiple blasting heights of proximity fuze due to the low ballistic extension of tank gun and the narrow beam of millimeter wave detector. A blasting height control model of millimeter wave proximity fuze for tank gun based on setting delay is established, and the strategy for increasing the ignition delay is analyzed to achieve the blasting height control. The ignition delay is calculated according to the initial firing angle and other attack conditions before launching, and the information crosslink between the weapon platform and the projectile is used to set the firing delay to the proximity fuze, so as to realize the blasting height control of projectile. A mathematical model is established, and the relationships among ignition delay, projectile initial velocity, firing angle, beam width of millimeter wave detector, detection distance and blasting height difference are analyzed by simulation. The calculation formula of ignition delay is summarized. The validity of the proposed method is verified by static test in laboratory and dynamic test in field.

Research on Anti-frequency Sweeping Jamming Method for Frequency-modulated Fuze Based on Sparse Recovery

YANG Jin, HAO Xinhong, QAO Caixia, CHEN Qile

2024, 45(6):  2044-2053.  doi:10.12382/bgxb.2023.0369

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An anti-jamming method based on time-domain jamming cancellation and signal sparse reconstruction is proposed for the problem of “premature explosion” or “misfire” of continuous wave frequency-modulated (FM) fuzes under frequency sweeping jamming. The location and duration of jamming are detected through time-domain outliers, and the abnormal data are eliminated to suppress the impact of the jamming on the fuze. For the signal sparsity caused by jamming cancellation in time domain, an optimization equation for differential frequency signal reconstruction based on sparse regularization terms is established, and an ADMM-based iterative reconstruction algorithm is proposed. The performance of the proposed method is verified by using the simulated and measured data. The results show that the method can be used to suppress the influence of frequency sweeping jamming, accurately obtain the target range-velocity information, and improve the ability of FM fuze to resist the frequencys weeping jamming with a signal-to-noise ratio of -15dB and a zero sample rate of less than 70%.

Effect of Hot Extrusion of SiC_p/2024Al Composites on Microstructure and Properties of Laser Welded Joint

HAN Rui, LI Xiaopeng, PENG Yong, YAN Dejun, WANG Kehong

2024, 45(6):  2054-2064.  doi:10.12382/bgxb.2023.0105

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Using SiC particle-reinforced aluminum matrix composites instead of aluminum alloys to manufacture the ship hulls or armored hulls is a potential way to solve the binary contradiction between maneuverability and protection. In the actual application, this material has different states due to different supply channels, which have greater impact on material welding. SiC_p/2024Al composite materials in different supply states are welded by laser beam, the weld formations of the material before and after hot extrusion are compared, and the influence of hot extrusion process on the weld formation and the phase and microstructure of welded joint is analyzed. The fracture behaviour of composite materials is analyzed and its fracture mechanism is determined through microhardness, tensile and other mechanical property tests. The results show that there are a large number of porosity defects in the laser-welded seam of SiC_p/2024Al composites sintered by hot pressing, and the highest tensile strength of the welded joint is 76MPa, which only reaches 28% of the strength of the base metal, and the material strength drops seriously after welding. After the hot-extruded composite material is welded by laser beam, the weld seam is complete, there is no air hole defect, and there is no obvious low hardness area in the welded joint. The tensile strength of welded joint reaches 124MPa, which is 60% higher than that of the welded joint before hot extrusion. Compared with the hot-pressed sintered material, the weldability of hot-extruded material is significantly enhanced, and the mechanical properties of welded joint are significantly improved.

Degrad Target Detection Algorithm

LIU Peng, XIONG Zeyu, JING Wenbo, FENG Xuan, ZHANG Junhao, LIU Tongbo, WU Xueni, XIA Xuan, WAN Linlin, ZHAO Haili

2024, 45(6):  2065-2075.  doi:10.12382/bgxb.2023.0180

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The target detection accuracy in the imaging test phase of armored vehicle dynamic performance assessment is closely related to the precision of weapon equipment identification and qualification. To address the degradation issues such as low target image contrast and poor discernibility, a degraded target detection algorithm based on improved YOLOv5 is proposed. The proposed algorithm utilizes a multi-branch grouping convolutional structure combined with deep and pointwise convolutions to construct a backbone feature extraction network, thus reducing the computational complexity of network parameters and improving the detection speed. The representation attention mechanism is introduced to enhance the representation capability of the targets. At the network output layer, a three-branch spatial feature fusion is introduced to combine the fine-grained feature information from low-level feature maps and the rich semantic information from high-level feature maps, preserving the details and edge semantic information of degraded target images. Experimental results demonstrate that, in the target dataset, the proposed algorithm achieves a detection accuracy of 90.88% in terms of mean average precision (mAP) and a detection speed of 52.74 fps. It can efficiently and accurately complete the target detection phase in the imaging test of dynamic performance assessment.

Anti-sweep-jamming Method for PD Radar Based on Variational Signal Decomposition

CHEN Qile, QIAN Pengfei, KONG Zhijie, QIAO Caixia, ZHANG Ruiheng

2024, 45(6):  2076-2084.  doi:10.12382/bgxb.2023.0037

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When the pulse Doppler radar is subjected to sweep-jamming, its receiver channel is saturated by the jamming signal, which causes the radar false alarm or miss alarm. Aiming at the above problem, an IF signal model of pulse Doppler radar under sweep-jamming is established, and a separation method of target echo and jamming based on signal variational decomposition (SVD) is proposed. The proposed method uses total variation regularization to decompose the IF signal into two components: pulse and low-frequency narrowband signal. The pulse corresponds to the target echo, while the low-frequency narrowband signal corresponds to the jamming. The ow-frequency narrowband signal and noise are eliminated, and the pulse is retained and processed to detect the real target. The effectiveness of SVD was verified by simulation. The results show that the method can still effectively separate the target echo and jamming under the condition that signal-to-jamming ratio is lower than -20dB, and greatly improve the target detection ability of pulse Doppler radar under the effect of sweep-jamming.