Table of Content

28 February 2023, Volume 44 Issue 2

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2023, 44(2):  0. 

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Contents

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2023, 44(2):  0. 

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Damage Behavior of Multi-layer Spaced Target Plates Penetrated by Reactive Composite Jet

WANG Haifu, HE Suo, CAI Yiqiang, XIANG Jing'an, SU Chenghai, GUO Huanguo

2023, 44(2):  325-333.  doi:10.12382/bgxb.2021.0755

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To study the behind-target damage effects of the reactive material double-layered liner (RM-DLL) shaped charge penetrating into the target plates, the penetration and deflagration behaviors of the composite jet impacting multi-layer spaced target are studied. The experiments, numerical simulations and theoretical analysis are used to investigate damage behaviors and mechanism of the reactive composite jet against multi-spaced target plates. The experimental results show that for a given RM-DLL shaped charge structure, comparing with the reactive material-copper jet, the reactive material-titanium jet produces a larger penetration hole in the steel ingot and causes serious deformation and even rupture to the spaced aluminum plates. Based on the combined damage behaviors, an analysis model of the rupture area on the spaced aluminum plates is established. The model shows that the rupture area is positively correlated with the effective mass of follow-thru reactive material and the hole-radius formed by the jet kinetic energy, and that the reactive material's effective mass has a more significant effect on the area. Based on the empirical parameters obtained from the experiments and numerical simulations, the model can further predict the rupture area of the aluminum plates under different reactive materials' effective mass, penetration holes formed by kinetic energy, and the plate thicknesses.

Penetration-deflagration Experiment and Coupling Mechanism of Reactive Liner Shaped Charge

SU Chenghai, LI Zongyu, ZHENG Yuanfeng, ZHENG Zhijian, GUO Huanguo

2023, 44(2):  334-344.  doi:10.12382/bgxb.2021.0645

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To investigate the penetration-deflagration behaviors and coupling mechanism of fluoropolymers based reactive liner shaped charge against steel target, the damage experiment of 73.5% PTFE (Polytetrafluoroethylene)/26.5% Al reactive liner shaped charge impacting the steel target is carried out, and the effects of stand-off on the penetration depth, penetration aperture, and burst behaviors of the steel target are obtained. The results show that the coupling damage effect of penetration and burst of reactive liner shaped charge on the steel target is most significant when the stand-off is in the range of 0.35CD~1.00CD. On this basis, combining the theory of quasi-steady incompressible fluid mechanics, a function between the penetration depth and reaction delay of the reactive jet is given by introducing the reaction delay, and the effective mass model of the reactive jet inside the penetration hole is further developed. Based on the modified Bernoulli equation, combining the interior explosion characteristics of the reactive jet, a theoretical model for the reactive jet's penetration aperture diameter is developed. Using the cylinder failure theory, a method for judging the burst behaviors of a steel target under the coupling damage effect of penetration and burst of the reactive jet is proposed. The theoretical model quantitatively describes the coupling damage the reactive jet causes to the steel target and reveals the mechanism for the expansion of the hole and burst of the steel target caused by overpressure after the armor penetration is terminated.

Damage Characteristics of Underwater Explosion Shock Wave and Bubble Load on Typical Cylindrical Shell Structure

ZHANG Yifan, LIU Liangtao, WANG Jinxiang, LI Heng, TANG Kui

2023, 44(2):  345-359.  doi:10.12382/bgxb.2021.0598

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To investigate the damage characteristics of the near-field explosion shock wave load and bubble load on the typical cylindrical shell structure of a scaled-down torpedo, the ALE method was conducted and the effects of explosion distance and charge position on the deformation and damage characteristics of the cylindrical shell structure were explored. The validity of the numerical simulation method was verified by comparing it with the experimental results of the evolution process of the explosion bubble near the wall. The interaction between the explosion bubble and the cylindrical shell was studied under different explosion distances and charge positions, and the damage mechanism of different forms of load such the shock wave, bubble pulsation, and water jet on the cylindrical shell structure was analyzed in detail. The results showed that the damage effect of the shock wave on the cylindrical shell structure is strongly influenced by explosion distance; the increase of explosion distance sharply weakens the damage caused by the shock wave on the cylindrical shell, while the charge position of the cylindrical shell has a weaker effect on the damage of the shock wave; the damage to the cylindrical shell is significantly influenced by charge position; when the charge is arranged below the cylindrical shell, the shell generated the maximum plastic strain under the combined effects of bubble pulsation and water jet.

Area Target Scattering Characteristics of Terahertz Fuze

ZHANG Guangwei, LI Ping, ZHANG Jihao, ZHANG Hongyun, LI Guolin, JIA Ruili

2023, 44(2):  360-367.  doi:10.12382/bgxb.2021.0649

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Multiple time-frequency analysis methods are used to study the echo signal scattering characteristics of two typical area targets (semi-desert grassland and alpine swamp) in Tibet. The results reveal the two-point scattering phenomenon of area targets of the terahertz fuze under the typical angle of falls of 65°and 85°. Based on Geometrical Theory Diffraction(GTD), the area target echo model of a terahertz fuze is established. The echo signal characteristics of multi-point scattering area targets and the application limitations of multiple time-frequency methods are analyzed. To address the problems of the loss of frequency components and the poor frequency component energy concentration in the analysis process, a new wavelet-rearrangement pseudo-Wigner time-frequency analysis method (Mor-RPWVD) is proposed. Distance weighting and time-frequency information fusion are employed to further improve the cross-term interference suppression ability and energy concentration of the time-frequency method. The analysis of the measured data has verified the good time-frequency analysis ability of wavelet-rearrangement pseudo-Wegener (Mor-RPWVD) under multi-point scattering conditions.

Rapid Identification of Autocatalysis Characteristics in Energetic Materials Decomposition Reactions

PING Chuan, GAN Qiang, ZHANG Rui, DU Zhenhua, FENG Changgen

2023, 44(2):  368-379.  doi:10.12382/bgxb.2021.0592

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Autocatalysis is one of the major reasons that make energetic materials extremely dangerous. The commonly used methods for identifying autocatalytic reactions is the “isothermal methods” based on differential scanning calorimetry (DSC) and microcalorimetry (C80). However, for these methods, temperature selection is one difficult problem, and the test period is long with some danger. So it is necessary to find a fast and safe method for the identification of autocatalytic reactions. This study proposes a method to quickly identify the characteristics of autocatalytic reactions and determine the reaction strength based on adiabatic thermal tests combined with reaction mechanism functions, which is used to measure the adiabatic thermal decomposition characteristics of five samples (20% DTBP and toluene mixed solution, HNS-IV, BNCP, CL-20, and CMC-LA). This method does not require the calculation of accurate reaction kinetic parameters, can identify the autocatalytic characteristics at the early stage of the autocatalytic reactions which reduces the measurement time and greatly reduces the risk in the process, and can quickly identify whether autocatalysis is involved in the decomposition of the substance and accurately characterize the autocatalytic intensity of the reactions.

Inertia Analysis and Vibration Filtering Buffer Design of Electromechanical Suspension of High Speed Tracked Vehicle

SONG Huixin, GU Liang, ZHANG Jinqiu, DONG Mingming, WANG Liming

2023, 44(2):  380-393.  doi:10.12382/bgxb.2021.0588

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In order to solve the problem of performance deterioration and ensure structural reliability of the electromechanical suspension of high-speed tracked vehicles in high-frequency zone, the stiffness characteristics of the electromechanical suspension based on the torsion bar are analyzed, the complex motion relationship of the suspension rod system is solved, the equivalent inertia mass of the electric actuator is calculated, and a two-degree-of-freedom electromechanical suspension model considering inertia mass and load wheel damping is established. We quantitatively analyze the adverse impact of inertia mass on suspension performance, and obtain the frequency domain distribution interval and power spectral density distribution interval of inertia force affecting suspension's ride comfort and component reliability. According to the frequency domain distribution of suspension inertia force and the amplitude frequency characteristics of the suspension's dynamic deflection, the measures of vibration filtering and buffering are put forward, and a suspension model with the vibration filtering buffer is established. The simulation and test results show that vibration filtering and buffering can effectively reduce the influence of inertial mass. Under the driving condition of 40km/h on class D Road, the root mean square value of the original inertial force is reduced from 2143N to 175N, and the root mean square value of sprung mass acceleration is reduced from 3.5108m/s² to 1.2682m/s². The bench test shows that the gear ring stress is greatly attenuated after the vibration filtering and buffering measures are adopted, and the maximum value is reduced from 519.9MPa to 110.1MPa. Through simulation and test, it is verified that the measures of vibration filtering and buffering can improve the performance of the electromechanical suspension and help to solve the problem of performance deterioration in the high frequency zone caused by inertial mass.

Hierarchical Trajectory Planning Algorithm based on Differential Flatness

ZHOU Xiaotian, REN Hongbin, SU Bo, QI Zhiquan, WANG Yang

2023, 44(2):  394-405.  doi:10.12382/bgxb.2021.0756

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To fully consider the influence of transverse and longitudinal coupling and vehicle kinematics on trajectory planning, a hierarchical optimization-based trajectory planning algorithm framework is proposed. The safe corridor constraint is designed with the convex hull of a Bezier curve. Taking the trajectory smoothness as the objective function, we obtain a lower planner based on Bezier curve nodes. In the upper planner, based on the transverse and longitudinal Bezier curves solved by the lower planner and the differentially flat output of the vehicle kinematics model, the objective function meeting the vehicle ride comfort, efficiency and safety requirements is constructed, and quadratic optimization is applied to the initial parameters of the Bezier trajectory by particle swarm optimization algorithm to obtain the driving trajectory with the best comprehensive performance. The simulation results show that: the algorithm has good ride comfort and traceability while ensuring safety; due to the high efficiency of quadratic programming and particle swarm optimization, this framework has strong real-time and probabilistic completeness.

Effects of Structural Characteristics of a Wet Multi-Disk Clutch on Contact Pressure

CHEN Man, LIU Yujian, YU Liang, WANG Xu, ZHANG Cunzhen, HU Lin

2023, 44(2):  406-416.  doi:10.12382/bgxb.2021.0618

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Based on the structural characteristics of a wet multi-disk clutch, a finite element model and a thermodynamic model of a multi friction-pair system are developed. The influence of structural parameters on the contact pressure between friction pairs are studied, including backplate thickness, circlip width, and number of friction pairs. Moreover, the correctness of the numerical model is verified by clutch static pressure experiments. An index is employed to evaluate the pressure differences between friction pairs, and the optimal structural parameters of the clutch are proposed. The results show that the backplate thickness and circlip width have strong effects on the pressure difference, while the number of friction pairs only has a slight influence. The differences between the contact pressure and radial temperature of friction pairs can be significantly smoothed out by increasing the plate thickness and circlip width. As compared with the initial structural conditions, the maximum differences of the control pressure and radial temperature at the optimum condition are reduced by 82% and 61%, respectively.

In-flight Alignment Method of Guided Projectile Roll Angle Based on Trajectory Bending Angular Velocity Single Vector

YANG Qifan, WANG Jiang, FAN Shipeng, BAI Chan, ZHOU Yongjia, HU Shaoyong

2023, 44(2):  417-427.  doi:10.12382/bgxb.2021.0707

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As the interior ballistics of guided projectiles feature high rotational speed and high overload, the initial alignment of roll angle can only be achieved in air. To solve this problem, a coarse roll angle alignment method based on trajectory bending angular velocity in free flight phase is proposed. Without satellite and maneuver assistance, using the trajectory bending angular velocity induced by gravity as reference, the roll angle is obtained by single vector attitude determination. Then, the frequency domain characteristics of the projectile attitude motion measurement is analyzed to reduce the impact of the zero bias, misalignment and other errors of the low accuracy gyroscope. A FIR bandpass filter is utilized to extract desired component of the angular rate measurement at the rolling frequency point. An integration strategy under the frozen projectile system at the beginning of alignment is adopted to suppress the random noise, thereby improving the performance of the alignment. The influence of inertial gyroscope error on alignment accuracy is explored by mathematical simulation. The simulation results show that through this method, fast coarse alignment of roll angle in free flight can be realized only using low precision angular rate gyroscope, and the error is about 1°. In the flight test, the roll angle alignment error can be controlled within 2°.

A Lag Angle Test Method for Actuators of Spinning Missiles Based on Improved SOGI-FLL

ZHANG Xin, LIN Fan, SHEN Xinjie

2023, 44(2):  428-436.  doi:10.12382/bgxb.2021.0563

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To address the problems of noise and DC offset in testing the lag angle of actuators of spinning missiles, an improved second-order generalized integrator frequency-locked loop (SOGI-FLL) algorithm is applied for processing test data and accurately calculating the lag angle. The essence of the test is to extract the phase of sinusoidal signals under the influence of noise and DC offset. By introducing the DC offset compensation loop into conventional SOGI-FLL, the algorithm is capable of suppressing DC offset disturbances. The improved SOGI-FLL shows the characteristics of a band-pass filter, which can realize filtering without lag and attenuation at the fundamental frequency of sinusoidal signal, effectively eliminating the influence of noise and DC offset. In the meantime, the output quadrature signals are supplied to phase locked loop (PLL) with PI controller for phase angle estimation. The simulation and experimental results show that the improved SOGI-FLL can effectively improve the lag angle processing accuracy compared with the traditional FFT method and correlation analysis method when the test signal is affected by noise and DC offset.

Finite Element Structural Analysis and Topology Optimization of a Vehicle-borne Missile Launching Cradle

NIU Cao, GU Guangxin, ZHU Lei, XU Hongbin, LI Zhengyu, ZHANG Weihong, CHEN Yongwei, WANG Bo, SHI Jianxiong, LI Yizhe

2023, 44(2):  437-451.  doi:10.12382/bgxb.2021.0561

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Launching cradle is a key load-bearing component of a vehicle-borne missile launcher. Its static and dynamic structural characteristics, such as structural stiffness and natural frequency, significantly affect the accuracy of missile launching. Using a vehicle-borne missile launching cradle as the research object, the loading characteristics are investigated through finite element modeling and analyses under various load conditions such as overloading during marching and missile-carrying. General guidelines for missile loading, unloading, and launch sequence planning are proposed based on the finite element analysis results. The launching cradle's topology optimization is then performed with multiple load conditions considered. The influence of manufacturing constraints as well as minimum and maximum member size constraints on the optimized topological configuration is investigated. The launching cradle is reconstructed according to the optimized configurations. Finite element analyses are carried out to verify the optimized design. Compared with the original design, the weight is reduced by 10.69% while both structural rigidity and strength are improved under almost all considered load conditions. The maximum improvement in structural rigidity reaches 21.47%, and the maximum reduction in equivalent stress reaches 31.97%. Meanwhile, the first six natural frequencies increase by more than 12%, which is of great significance for reducing launching disturbances.

Prediction of Projectile Muzzle Velocity Based on Neural Network Algorithm Combined with Clustering Association Rules

TIAN Ke

2023, 44(2):  452-461.  doi:10.12382/bgxb.2021.0687

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In view of the situation that reconstruction is needed for the muzzle velocity of a projectile measured by muzzle velocity radar in the range test, the data of two radars used in the test at the same time are fused to establish a neural network model, and the data of one radar is used to predict the data that needs to be reconstructed by the other radar. Because the prediction accuracy of the prediction model depends on the quality of the model, and the model quality depends on the quality of the sample data, we first use cluster analysis and association rules to mine high-quality samples from a large number of historical test data, and then establish a neural network for prediction. The experimental results show that: compared with support vector regression machine, the prediction accuracy of the combined algorithm constructed by clustering analysis association rules and neural network is higher, the error of predicting similar historical data is far less than 1‰, and the accuracy of predicting data significantly different from historical data is also more reasonable. The prediction results in the two cases show that the combined algorithm not only ensures the prediction accuracy, but also has certain robustness, and can be used as the prediction model of projectile muzzle velocity.

Ballistic Trajectory Prediction Based on Context-enhanced Long Short-Term Memory Network

REN Jihuan, WU Xiang, BO Yuming, WU Panlong, HE Shan

2023, 44(2):  462-471.  doi:10.12382/bgxb.2021.0489

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Trajectory prediction based on observed data is critical to the modern army's precision strike capability. Yet, the existing trajectory prediction methods have suffer from low accuracy and poor real-time performance. Thus, this study proposes a new model called Context-enhanced Long Short-Term Memory(CE-LSTM) Network to make an accurate long-term prediction of the exterior trajectory of incoming projectiles. The proposed method inherits the LSTM network's advantage in that it can approximate any nonlinear function and it has a long-term memory. Furthermore, we create a mixture output unit of the hidden layer to extract short-term context information and approximate the motion states of the incoming projectiles more accurately. The CE-LSTM network is trained with a large-scale dataset consisting of exterior trajectories under different initial conditions to obtain the optimal hyper-parameters. The experimental results show that compared with the methods like external ballistic differential equations and the Gaussian mixture model, the CE-LSTM network performs significantly better in prediction accuracy, and its prediction speed increases by three to ten times. Moreover, the proposed method is highly generalizable.

Formation Recognition and Target Selection of Anti-ship Missile Based on Hough Transform and Optimized K-means Clustering

HUANG Jun, WU Pengfei, LI Xiaobao, LIU Yue

2023, 44(2):  472-483.  doi:10.12382/bgxb.2021.0660

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For the formation recognition technology of anti-ship missiles, there are problems of focusing on formation recognition rather than target selection, insufficient consideration of the changes from terminal guidance stage to target indication stage, and relatively weak real-time performance and so on. The formation recognition target selection technology has replaced the single feature recognition target selection technology and become the mainstream of target selection for long-range anti-ship missile weapon systems based on Hough transform and optimized K-means clustering algorithm. A process of formation recognition and target selection for anti-ship missiles is proposed, and models on targets' generation, selection and changes, such as formation rotating, scaling, transforming and dilution jamming, of V-shaped, parallel and ring formations are built up. The simulation results show that: the cost function for optimal clustering number is more effective than the existing methods; the problem for the lack of transforming mechanism for the sample points on both sides of the normal detection interval is solved using the formation line detection on the moving detection interval; the clustering iteration, optimal iteration of clustering number, and fused cluster iteration by combining multi-sample update clustering with single-sample update clustering have higher efficiency and stronger engineering applicability, which is of great significance for anti-ship combat simulation.

Q-Learning-based Multi-UAV Cooperative Path Planning Method

YIN Yiyi, WANG Xiaofang, ZHOU Jian

2023, 44(2):  484-495.  doi:10.12382/bgxb.2021.0606

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To solve the path planning problem of multiple UAVs' synchronous arrival at the target, the battlefield environment model and the Markov decision process model of the path planning for a single UAV is established, and the optimal path is calculated based on the Q-learning algorithm. With this algorithm, the Q-table is obtained and used to calculate the shortest path of each UAV and the cooperative range. Then the time-coordinated paths is obtained by adjusting the action selection strategy of the circumventing UAVs. Considering the collision avoidance problem of multiple UAVs, the partical replanning area is determined by designing retreat parameters, and based on the deep reinforcement learning theory, the neural network is used to replace Q-table to re-plan the partical path for UAVs, which can avoid the problem of dimensional explosion. As for the previously unexplored obstacles, the obstacle matrix is designed based on the idea of the artificial potential field theory, which is then superimposed on the original Q-table to realize collision avoidance for the unexplored obstacle. The simulation results verify that with the proposed reinforcement learning path planning method, the coordinated paths with time coordination and collision avoidance can be obtained, and the previously unexplored obstacles in the simulation can be avoided as well. Compared with A^* algorithm, the proposed method can achieve higher efficiency for online application problems.

A Composite Sliding Mode Control Scheme Based on Reaction Jets and Flaps for Near-Space Hypersonic Vehicles

DONG Jinlu, MA Yuemeng, ZHOU Di, GONG Xiaogang, ZHANG Xi, SONG Jiahong

2023, 44(2):  496-506.  doi:10.12382/bgxb.2021.0690

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To address the underactuation and strong coupling of lifting-body hypersonic reentry vehicle, a composite sliding mode control scheme based on reaction jets and flaps is proposed. Due to the thermal protection requirements, instead of traditional rudders, two body flaps are mounted at the aft windward side of the vehicle to control pitch, yaw and roll channels. The continuous high-frequency and wide-margin vibration of the sideslip angle caused by strong aerodynamic coupling will cause aileron to saturate for a long time, leading to an instable control system. To alleviate the vibration of the sideslip angle and realize quick convergence, an integrated control system is built by employing a pair of reaction jets that can be turned on or off as auxiliary actuators in the yaw channel. Then, based on the linear quadratic optimal control and sliding mode control theory, the control laws for flaps and reaction jets are designed. Simulations using the new composite control scheme and a conventional flap-based control scheme are compared under two command tracking conditions. The results show that the composite control system can effectively suppress the chattering phenomenon of the yaw channel, leading to a rapid convergence of the sideslip angle. Moreover, the novel scheme also improves the stability and speed of tracking in pitch and roll channels.

Crack Detection System for Aircraft Protective Grill based on Machine Vision and Deep Learning

ZHANG Liang'an, CHEN Yang, XIE Shenglong, LIU Tongxin

2023, 44(2):  507-516.  doi:10.12382/bgxb.2021.0674

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To address the problems of low efficiency and poor reliability in the crack detection of traditional aircraft protective grill, a crack detection device is designed based on machine vision technology. Combined with image processing technology and deep learning principles, a crack detection and calculation method for aircraft protective grill is proposed. Firstly, a detection system is designed, and the image recognition algorithm of protective grill is studied, and then, the crack images of aircraft protective grill are collected and sorted, and the crack detection data set is studied and made. Secondly, the ZF-Net, VGG-16 and ResNet-101 convolutional neural networks are used as the feature extraction networks of Faster-RCNN to detect surface cracks and defect cracks of the aircraft protective grill. The experimental results show that: the three models can achieve good detection accuracy, which are 92.79%,95.12% and 97.54% respectively; the Resnet-101 network has the best detection effect; compared with the existing machine vision detection method for protective grill cracks, the missed detection rate and false alarm rate are reduced by 22.54% and 89.28% respectively, and the detection rate is improved by 22.54%. Further research shows that the ResNet-101 network still has high detection accuracy under different lighting conditions, which shows the effectiveness of the detection device and detection algorithm. This research provides a new method for crack detection of the aircraft protective grill.

Acoustic Scattering Prediction Method of Underwater Vehicles Based on Slice-parameterized Multi-highlight Model

LIU Jinwei, PENG Zilong, FAN Jun, LIU Yan, KONG Huimin

2023, 44(2):  517-525.  doi:10.12382/bgxb.2021.0764

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To deal with the problem of low accuracy of the elementary highlight model in forecasting the acoustic scattering characteristics of underwater vehicles, a highlight model which can reflect the real lines and fine acousitcscattering characteristics of underwater vehicles is established.The linear interpolation algorithm and object segmentation method are used to establish the parametric highlight model of the command station and stern, and the planar elements method is adopted to verify the results.On this basis, the acoustic scattering characteristics of the Benchmark submarine model including the command station and stern are studied and compared with the standard solution of the BASIS method.The target strength experiment results of the Benchmark submarine scale model are obtained through acoustic scattering experiments of the model on lake, and then compared with the method of highlight model.The results show that the proposed model is accurate.Considering the spatial phase information of each component, the highlight model can forecast the acoustic scattering characteristics of underwater vehicles well.The findings of this study can provide insights into the fast prediction of acoustic scattering of underwater targets and have broad application prospects in the fast time-domain echo forecasting.

Underwater Magnetic Sensor Position Correction Method Based on Multi-Population Particle Swarm Optimization Using Dynamic Learning Strategies

WANG Yufen, ZHOU Guohua, WU Kena, LI Linfeng

2023, 44(2):  526-533.  doi:10.12382/bgxb.2021.0740

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Laying magnetic sensors on the seabed of the magnetic deperming facility is one of the main ways to measure ships' magnetic field. The position deviation of underwater magnetic sensors directly affects the measurement accuracy and evaluation of protection ability of ships' magnetic field. To address the problem that the existing methods are difficult to accurately locate the underwater magnetic sensors of the deperming station, a position correction method of underwater magnetic sensors of the deperming station based on multi-population particle swarm optimization (PSO) using dynamic learning strategies is proposed. Firstly, the energized current-carrying coil is equivalent to a magnetic dipole magnetic source, and then the relative position between the magnetic source and the magnetic sensor is changed by the linear multi-measurement method to obtain the magnetic field measurement data of the multiple groups of magnetic sensors. Based on this, the position correction model of underwater magnetic sensors is established, and the position deviation vector is optimized by the multi-population PSO algorithm using dynamic learning strategies, thus realizing the high-precision correction of the position of the underwater magnetic sensors. Based on the comprehensive analysis of the main influencing factors such as the equivalent error of the magnetic dipole, the numerical simulation and physical scale model experiment are designed. The results show that: this method can effectively solve the problem of position correction of underwater magnetic sensors in the deperming station; after correction, the position errors in x,y and z directions are less than 0.1m; the magnetic field measurement accuracy of the deperming station after correction can meet the requirements of ships' magnetic field measurement. This method can complete the correction of the underwater magnetic sensors with a position deviation of no more than 0.3m, and has good practical value.

Graph Feature Learning-Based Sea Clutter Suppression Method

CHEN Peng, XU Zhen, CAO Zhenxin, WANG Zongxin

2023, 44(2):  534-544.  doi:10.12382/bgxb.2021.0662

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In order to reduce the effect of sea clutter on Marine radar,a sea clutter suppression algorithm based on graph feature learning is proposed. The time-frequency transform is used to amplify the dimension of radar echo signal,and based on the idea that the graph structure features can be deeply mined by graph embedding processing, a method of constructing signal node feature vector by graph embedding is presented according to the different structural characteristics of sea clutter and target echo signal in time spectrum. Different from traditional methods such as time domain cancellation and subspace decomposition,this method can be used to implement sea clutter suppression through node classification of different signals in the time spectrum. Simulation and experimental results show that the algorithm can effectively suppress the sea clutter component of radar echo signal,improve the signal to clutter ratio of radar echo signal,and provide a new idea and way for ocean radar to suppress sea clutter.

A Modulation Recognition Algorithm of DP-DRCnet Convolutional Neural Network

WANG Yang, FENG Yongxin, SONG Bixue, TIAN Binghe

2023, 44(2):  545-555.  doi:10.12382/bgxb.2021.0620

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How to ensure higher signal modulation recognition accuracy while reducing system network overhead is a important problem currently faced by the convolutional neural networks.To this end, a lightweight convolutional neural network is proposed.This networkis split into two paths to parallelly extract auto-correlation and cross-correlation features of signal.Then. features from these two paths are combined so that the network can ultimately achieve classification and recognition with different modulation modes. In addition, the overhead of the network is controlled by adopting the scheme of controlling the input data dimension of the convolution layer and the number of convolution cores in the model.The recognition verification of different modulation modes is performed.The experimental result shows that: the average recognition accuracy reaches 86.5% when the signal-to-noise ratio is in the range of -6~12dB;compared with the conventional convolutional neural network, the computational load is reduced by 94.44%; compared with the regular lightweight convolutional neural network, the computational load is reduced by 67.6%.The performance of the proposed network is better than the existing modulation recognition methods based on lightweight convolutional neural network.

A Random Error Compensation Method of MEMS Gyroscope Based on BP Neural Network Combined with PSO-Optimized Kalman Filter

WAN Xinwei, WANG Jing, YANG Hui, LI Yi, ZHANG Yuanzai, WANG Lu

2023, 44(2):  556-565.  doi:10.12382/bgxb.2022.0110

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To deal with the large random error of the micro-electro-mechanical-system (MEMS) gyroscope that affects its accuracy, an error compensation method based on BP neural network combined with Quantum-behaved Particle Swarm Optimization (QPSO)-optimized Kalman Filter (KF) is proposed. First, the MEMS gyroscope and turntable data are collected as samples, and the BP neural network is employed for training to establish the error model; then the error of the MEMS gyroscope is compensated by the model; finally, the QPSO algorithm is used to optimize KF to achieve better noise reduction effect. The experimental results show that compared with other methods like BP-KF, QPSO-KF and VMD-WTD, this method has better denoising effect, and the MAE and MSE values of the denoised data are smaller.

High-Sensitivity Follow-up Control Technology Based on Micro-Inertial Sensors

ZHANG Tian, JIN Shuxin, WANG Qiang, DUAN Xiaobo, LIU Tiecheng, NIU Haitao, HOU Zeng, YANG Yi, LIU Tong

2023, 44(2):  566-576.  doi:10.12382/bgxb.2021.0584

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The current follow-up control equipment is difficult to meet the requirements of real-time, accuracy and stability for sensors and actuators. Problems such as high control delay and low accuracy exist, greatly limiting the applications of such equipment. To address the above problems,this study proposes a low-delay and high-precision follow-up control technology based on MEMS inertial devices and fuzzy control pan/tilt. This technology uses a micro-inertial unit (MEMS IMU) to obtain high-sensitivity attitude dataand uses the attitude data to perform real-time and high-precision follow-up control of the high-precision pan/tilt. Compared with traditional technical means, the improved real-time acquisition algorithm optimizesthe high-frequency position closed-loop fuzzy PID control of the pan/tilt and realizes low-delay and high-precision follow-up control functions at low cost. According to the measurement results, the system achieves a pan-tilt position response accuracy of 1.478deg (1σ) within 88.17ms after the continuous action command is issued, which can meet the needs of high-sensitivity follow-up control. This application is suitable for UAV control and observation,vehicle radar and weapon station control, etc., which can greatly reduce the complexity of equipment control and enhance control characteristics.

Efficient Design Method of Multi-condition and Static and Dynamic Reinforced Wall Structure for Modular Base of Weapon Station

WAN Ziping, TAN Ruoyu, ZHENG Jieji, REN Guang'an, XIE Xin, FAN Dapeng

2023, 44(2):  577-590.  doi:10.12382/bgxb.2022.0183

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To meet the requirements of excellent multi-condition adaptability and dynamic performance index for the modular base of a weapon station, an efficient design method of multi-condition and static and dynamic reinforced wall structure for the modular base of the weapon station is proposed and verified. Firstly, the comprehensive objective optimization functions under multi-condition and multi-order modes are deduced, and the weights of multi-condition and multi-order modes are determined via the analytic hierarchy process and linear weighting method respectively. Then,a multi-condition and static and dynamic topology optimization method based on superelements is proposed to overcome the disadvantage of high computational cost under the comprehensive objective optimization function. At the same time, the response surface design and optimization method for the reinforced wall structure based on sensitivity analysis is proposed, which can reduce the topology optimization time of the modular base by 92% and the test design time of the response surface by 83.7%. Finally, the verification results shows that the modular base of the weapon station designed in this paper can not only adapt to a variety of working conditions but also has good static and dynamic characteristics besides meeting various performance indicators, which has some guiding significance for the reconfigurable efficient design of weapon station products.

Optimization of Two-Echelon Configuration of Maintenance Supply for Synthetic Forces based on Task Evolution Importance

WU Weiyi, JIA Yunxian, SHI Xianming, LIU Bin, LIU Jie, YIN Shizhuang, ZHU Xi

2023, 44(2):  591-604.  doi:10.12382/bgxb.2021.0701

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Maintenance supply is an important material basis for the implementation of maintenance support, which directly affects the readiness of arms. In this paper, we analyze the operating mechanism of the two-echelon maintenance support system of the synthetic force and establish an importance analysis model based on task evolution structure. Then, the spare parts support degree is deemed as the objective to shorten the delay time and improve the availability, and a two-echelon dynamic configuration optimization model of equipment with multiple constraints on equipment volume, quality, importance, and cost is established. The Lagrange operator is introduced to convert multiple constraints into composite single factor constraints, and a dynamic update mechanism of constraint factors is established to meet the commander's different weight factor judgment rules timely. Finally, an improved margin analysis method based on MA-OD target decomposition is proposed. The numerical analysis shows that the proposed model provides effective support for the commander of the synthetic force to make the military equipment deployment plan in both peacetime and wartime, which is of great significance to improving the readiness.

Interfacial Microstructure and Mechanical Properties of Steel-copper Heterostructure Prepared by Selective Laser Melting

LI Zhonghua, CHEN Yanlei, LIU Bin, KUAI Zezhou, LU Shengyu, SHI Jingshuai

2023, 44(2):  605-614.  doi:10.12382/bgxb.2021.0721

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The composite forming by machining and selective laser melting (SLM) can realize the formation of parts with high efficiency, low cost and heterogeneous materials. The preparation of copper alloy with high thermal conductivity by SLM on the high-strength machined steel substrate was investigated, and the complex bimetallic structure was formed by combining the SLM technology with traditional machining technology. CuSn10 alloy was fabricated by SLM on machined 316L matrix. The interfacial microstructure and mechanical properties of steel copper heterostructure manufactured by composite forming were clarified. The microstructure and element distribution at the interface were observed and analyzed by metallographic microscope, scanning electron microscope and energy spectrum inpspection. The mechanical properties of the steel copper heterostructure were analyzed by tensile test and microhardness measurement. The results showed that: steel and copper diffused and penetrated each other, and a metallurgical bonding area surrounded by steel and copper was formed at the interface; microcracks were found in the bonding area near the 316L matrix and extending to the 316L matrix; the tensile strength of the bonding area reached 361.65MPa±5.45MPa and the elongation was 3.9%±0.1%; the microhardness at the interface gradually decreased from 244.9HV in 316L matrix area to 155.1HV in CuSn10 area. The experimental results revealed that the steel copper heterostructure formed by the combination of machining and SLM has good interface bonding and mechanical properties.

Deformation of the Multi-point Support Structure and Loading Performance Analysis of Its Shafting Bearing

NIU Rongjun, LIU Yue, TANG Hongli, CUI Yongcun, DENG Si'er

2023, 44(2):  615-628.  doi:10.12382/bgxb.2021.0575

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With the development of high power-density transmission systems, shafting bearings must meet higher standards such as a high load-bearing capacity and long service life. This study establishes a mechanical model for a multi-point support shafting bearing based on the theory of elasticity and the design method for rolling bearings. The deflection deformation curve of shafting, as well as the load distribution, contact angle, and contact stress of bearings, are numerically calculated. Then, the influence of driving torque and position on bearing life is analyzed, and the optimal configuration parameters of the shafting structure are given. The results show that the deflection of multi-point support shafting significantly affects the load distribution of shafting bearings. When evaluating the service life and performance of multi-point support shaft bearings, the coupling effect of shaft deflection and shafting bearing should be considered. In terms of the optimal crowning design for multi-point support cylindrical roller bearings, arc-slope crowning on both sides is selected for the middle row roller bearing, and the full crowning type is selected for the right-end roller bearing, which will help prolong the service life of the bearing. To meet the safety requirement of 80% climbing rate, when the driving torque is 800N·m under normal working conditions, the maximum design contact angle of the inner ring raceway is 40.6°, and that of the outer ring raceway is 44.3°. Adjusting the load position of helical gears can significantly prolong the service life of shafting bearings. When the distance between the ends is 41~46mm, the shafting bearings have a maximum life.