Table of Content

30 September 2020, Volume 41 Issue 9

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Contents

2020, 41(9):  0. 

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Paper

Modeling and Simulation of Electromagnetic Railgun Launching Process Based on a Transient Multi-physical Field Solver

LIN Qinghua， LI Baoming

2020, 41(9):  1697-1707.  doi:10.3969/j.issn.1000-1093.2020.09.001

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A mathematical model, including the circuit, electromagnetic field, thermal field and structural field, is established to study the interaction mechanisms and inherent laws of transient multi-physical fields in the launching process of an electromagnetic railgun. Some actual factors, such as material nonlinearity, structural deformation, contact and collision, are also accounted in the model. The electromagnetic and thermal fields are solved by the implicit finite element method, the structural field is solved by the explicit finite element method, and these fields are coupled by load transfer and time synchronization. Thus a transient multi-physical field solver was developed. The rationality of the calculated results is discussed by taking the launching processes of solid-armature railgun and synchronous induction coilgun as example. The results show that the launch of an electromagnetic gun is a complex dynamic process under multi-physical field coupling and multi-body interaction, in which some transient phenomena, such as current and magnetic field diffusion, temperature rise, stress propagation, contact and collision, exist. The launching performance is closely related to the structures, material properties and excitations.

Video Object Detection Method for Tank Fire Control System Based on Spatial-temporal Convolution Feature Memory Model

DAI Wenjun， CHANG Tianqing， CHU Kaixuan， ZHANG Lei， GUO Libin

2020, 41(9):  1708-1718.  doi:10.3969/j.issn.1000-1093.2020.09.002

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Video object detection technology is an effective means to improve the battlefield object search capability of tank fire control system. In view of the video object detection task of tank fire control system，a video object detection method based on spatial-temporal convolution feature memory model is proposed. The spatial-temporal convolution feature alignment mechanism is combined with convolutional gated recurrent unit to construct a spatial-temporal convolution feature memory model，which can simultaneously model the apparent features and motion information of object in multiple video frames to transfer and fuse the object information in video frames. The feature extraction network and the detection sub-network are combined with the deformable convolution networks，and the non-maximum suppression of video sequences is used in the detection process to improve the performance of detection for deformed and occluded objects. A tank fire control system video object detection dataset is established，which considers different object types， scales，occlusions and other conditions，and can provide the basis for testing for different video object detection methods. The test results show that the mean average precision of the proposed method is the higher than those of R-FCN，D&T and MANet，and the proposed method can better meet the application requirements of equipment.

Constitutive Model of Flexible Composites for Rubber Track

ZHAO Zihan, MU Xihui, DU Fengpo

2020, 41(9):  1719-1726.  doi:10.3969/j.issn.1000-1093.2020.09.003

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The performance of rubber track is one of the key factors affecting the service life of tracked walking mechanism. In order to characterize the mechanical behavior of rubber track with large deformation, nonlinearity and anisotropy in the driving process, the test study of uniaxial tension of rubber-cord composites at different off-axis angles is carried out. The influence of cord off-axis angle on the mechanical properties of the composites is analyzed. A constitutive model involving interaction between rubber and cords is established. Based on the particle swarm optimization and Newton iteration method, an optimization algorithm for parameters fitting is proposed. The model parameters are obtained from the uniaxial tension data with cord off-axis angles of 90°, 0° and 15°. The uniaxial tension data with cord off-axis angles of 45° and 60° are predicted. The results show that the coefficients of determination, R², are 0.992 8 and 0.982 9, respectively. The proposed model is validated by comparing the numerical results with the uniaxial tension data. The maximum simulation error is about 10.86%, which further verifies the reliability and adaptability of the proposed model to finite element analysis.

Effects of Key Parameters of Integrated Power System on Vehicle Stability

GAO Qiang， LIAO Zili， YUAN Dong， LIU Chunguang

2020, 41(9):  1727-1735.  doi:10.3969/j.issn.1000-1093.2020.09.004

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The instability of the vehicular integrated power system due to its limited volume capacity，more converters and complex working condition is studied. The small signal models of each source and load converter are proposed，from where the output impedance and load input impedance are obtained. The stability criterion of small signal of the vehicular integrated power system is established based on an improved impedance criterion in which the requirements of both the system amplitude and the phase margin are considered. The effects of super-capacitor， filter inductor of DC/DC converter，DC-link capacitor，and speed and torque of driving motor on the system in engine-off operation mode are analyzed by using Bode diagram. Finally，the stability criterion and the theoretical analysis are validated using the simulated results. The methods are used for the evaluation of system stability and the optimization of system design.

Parameter Identification and Sensitivity analysis of Gun Elevating Equilibrator

LIN Tong， QIAN Linfang， FU Jiawei， WANG Mingming

2020, 41(9):  1736-1744.  doi:10.3969/j.issn.1000-1093.2020.09.005

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In order to accurately simulate the dynamic response of the elevating equilibrator in the state of gun launch, an elevating equilibrator dynamic model in the state of gun launch is established based on the theoretical model of air-liquid mixtures of hydraulic oil， the cylinder stiffness and the structure of elevating equilibrator. ADAMS software is used to build a parameterized dynamic model of elevating equilibrator， and the parameters to be identified are established. The model parameters are identified using the particle swarm optimization algorithm based on the test data of a vehicle-mounted gun and the gun launching dynamics model. The simulated results agreed with the experimental data， thus verifying the accuracy of the proposed model and the availability of the parameter identification results. The sensitivities of the parameters of elevating equilibrator dynamic model to the pitching motion of gun were calculated．The results of sensitivity analysis show that several parameters， such as air content and initial pressure， have a large impact on the pitching motion of gun.

Adaptive Sliding Mode Control for Electro-hydraulic Servo System of Ammunition Manipulator Based on Disturbance Observer

NIE Shoucheng， QIAN Linfang， CHEN Zhiqun， WEI Yukai， YIN Qiang

2020, 41(9):  1745-1751.  doi:10.3969/j.issn.1000-1093.2020.09.006

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A disturbance observer-based adaptive sliding mode control strategy is proposed for ammunition manipulator electro-hydraulic servo system with unmatched and parameter uncertainties. A disturbance observer is adopted to estimate the unmatched uncertainties in the system, and the stability of disturbance observer is proved by Lyapunov stability theory. In order to effectively compensate the unmatched uncertainties and improve the control accuracy, the disturbance observer is introduced into the design of integral sliding mode switching function. An adaptive law is introduced into the design of sliding mode controller to improve the dynamic performance, which reduces the influence of system parameter uncertainties. Besides, the global stability of the controller is proved. Experimental results show that the disturbance observer and the adaptive law can accurately describe the system characteristics, the disturbance observer-based adaptive sliding mode controller proposed in this research tracks the desired tracking trajectory well. The designed controller has strong robustness and guarantees prescribed dynamic tracking characteristics and final steady-state accuracy under different operating conditions.

Buffering Mechanism and Characteristic Optimization of Ultra-light Artillery Backtrail

ZHANG Cheng， LIU Zhaoyang， GU Keqiu

2020, 41(9):  1752-1761.  doi:10.3969/j.issn.1000-1093.2020.09.007

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Launching stability is a key constraint in the design of ultra-light artillery. Through the analysis of the firing dynamics of the whole artillery, the influences of two kinds of buffer arrangement schemes on the firing stabilities of an artillery designed with tranditional structural principle (A-type) and an artillery designed with new structural principle (B-type) are analyzed, and the corresponding optimization design of buffer characteristics is also carried out. The results show that the effect of backtrail buffer on improving the firing stability of A-type artillery is not obvious; it is beneficial for B-type artillery to improve the stress on the backtrail and increase the firing stability by adding the backtrail buffer on its top.

Adaptive Threshold Setting Method for Layer-count in Penetration Fuse

HUANG Shaling， ZHU Hongzhi， CHENG Xiangli， XIE Yubin

2020, 41(9):  1762-1771.  doi:10.3969/j.issn.1000-1093.2020.09.008

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At present，the layer-count algorithm of penetration fuse usually uses one or more fixed thresholds to judge the target layer. The setting of threshold usually depends on the prior data. And there is no such a threshold which can fit all test conditions. For this problem， an adaptive threshold layer-count algorithm is proposed based on the fusion signal algorithm. The proposed algorithm uses the sensor signals collected by fuse to calculate the decision threshold of the next target in real time and online. Then the current number of layers is identified according to the calculated threshold. The simulated results show that the proposed algorithm can give the layer identification signal correctly under different test conditions compared with the fixed threshold algorithm.And the layer identification signal given by the proposed algorithm is in good agreement with the time recorded by high-speed camera in the actual test.

Spatiotemporal Distribution Characteristics of Smoke Mass Concentration of Smoke Pot

YANG Shangxian, CHEN Huimin, GAO Lijuan, MA Chao, QI Bin, DENG Jiahao

2020, 41(9):  1772-1782.  doi:10.3969/j.issn.1000-1093.2020.09.009

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Smoke pot is an effective means to implement the passive interference to near-earth laser weapon system. The spatiotemporal distribution characteristics of smoke mass concentration of smoke pot is studied to accurately obtain the laser transmission characteristics in the smoke environment. Based on the discrete phase diffusion model, Fluent software is used to simulate the smoke diffusion process of a small smoke pot. The spatial and temporal distribution characteristics of smoke mass concentration at different stages after the release of smoke, as well as the influence laws of wind speed, mass flow rate and other parameters on the diffusion velocity and mass concentration distribution of smoke were analyzed. The results show that the smoke is like an umbrella during spurting when there is no wind, and when the spurting stops, the smoke is like a cloud in the diffusion stage and there is a smoke ring with high mass concentration. The optimum wind speed under the simulation conditions is around 2-3 m/s. The spatial mass concentration of smoke has a linear relationship with the mass flow rate.

Bottom Temperature Simulation of Explosive Charge in High-speed Rotating Projectile in Internal Ballistic Process

PENG Jiacheng， JIANG Jianwei， LIAO Wei

2020, 41(9):  1783-1791.  doi:10.3969/j.issn.1000-1093.2020.09.010

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This paper concerns on the safe launch of high-speed spinning projectile filled with pressed charge. A calculation model for the the variation in temperature of explosive charge due to friction in in the moving process in bore is established based on the theory of friction heating, heat transferring and temperature rising. A crash accident of a highly rotating projectile occurring after it exits from the muzzle is taken for an example. The model parameters, including the pressure on the bottom of charge, and the relative angular velocity of charge and projectile body, were obtained by using LS-DYNA software to simulate the internal ballistic process of projectile, and MATLAB was used to obtain their specific function form. The variation in temperature of explosive charge in the moving process in bore was culculated. The results show that an obvious relative rotation of charge and projectile body occurs when the environment temperature reaches to 50 ℃. Hence, an amount of heat is generated from the strong friction of charge and projectile body at the bottom of explosive charge. Part of the heat is transmitted to and warms the charge so that the highest temperature is 302.3 ℃ at the bottom of charge, which is much higher than the thermal decomposition temperature. A large number of hot spots are generated on the charge surface and grow rapidly in the confined space, finally causing exploding.

Shock Response of HMX Single Crystal at Elevated Temperatures

DING Kai， WANG Xinjie， WU Yanqing， HUANG Fenglei

2020, 41(9):  1792-1799.  doi:10.3969/j.issn.1000-1093.2020.09.011

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A heating device which can heat up the explosive sample before experiment is designed to investigate the shock response of octogen (HMX). The designed heating device is used to conduct the plate impact experiments of HMX single crystal at elevated temperatures of 323 K， 373 K and 423 K. The particle velocities on the interface between HMX single crystal and window at different elevated temperatures are measured by using a velocity interferometry system for any reflector (VISAR). The corresponding elastoplastic mechanical parameters of HMX single crystal are obtained by the wave impedance matching method. At an impact velocity of about 300 m/s， the particle velocity curves on the interface between single crystal and window show a distinct elastic-viscoplastic double wave structure. It is found that the Hugoniot elastic limit has no obvious temperature dependence at the elevated temperatures of 323 K and 373 K， which indicates that the plastic deformation mechanism is unchanged. At high elevated temperature of 423 K， the Hugoniot elastic limit increases， showing a thermal hardening effect. The plastic deformation mechanism may change from thermal activation to phonon resistance.

Comparation of Solid Propellant Micromodels with and without Damage at Initial Particle/matrix Interface

HOU Yufei， XU Jinsheng， ZHOU Changsheng， CHEN Xiong， LI Hongwen

2020, 41(9):  1800-1808.  doi:10.3969/j.issn.1000-1093.2020.09.012

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Impregnation capability at particle/matrix interface deteriorates during the preparation of composite solid propellant due to manufacturing and environmental factors，which leads to the initial defects in composite solid propellant. In order to analyze how initial defect affects the mechanical property of solid propellant，a microscopic particle packing model is created by applying the molecular dynamics method. An exponential cohesive model for particle/matrix interface is developed by vectorized user defined material subroutine(VUMAT). Moreover，an initial damage model，in which the distribution of density function of bond strength at propellant particle/matrix interface obeys Weibull function，and a damage-free model of particle/matrix interface with the same bond strength are established.Comparison of the numerical results of two models shows that the mesh sensitivity of the initial damage model is lower than that of the damage-free model.In the initial damage model，the smaller the shape parameter is，the higher the damage is，and the lower the initial modulus is. Through experiments and simulations，it could be seen that the initial damage model can be used to describe the damage characteristic more accurately in uniaxial tension compared to the damage-free model.

Numerical Simulation of Rayleigh-Taylor Instability Perturbation Growth in High-purity Copper Interface

LI Biyong， PENG Jianxiang， GU Yan， YIN Xiaochun， HE Hongliang

2020, 41(9):  1809-1816.  doi:10.3969/j.issn.1000-1093.2020.09.013

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The two-dimensional simulations of Rayleigh-Taylor instability perturbation growth of an initial perturbed copper interface under explosive loading are performed to study the Rayleigh-Taylor instability of metal interface under high pressure and high strain rate loading.A numerical simulation model for the perturbation growth behavior of metal interface is established based on the two-dimensional finite difference code AUTODYN，and the effects of initial perturbed characteristics and material strength property on the perturbation growth behavior of metal interface are mainly analyzed.The simulated results show that the growth of the pre-perturbed copper interface is closely related to its perturbated initial wavelength and amplitude，and a critical amplitude exists.For the stable case，the ultimate perturbation amplitude after a transient phase increases with the increase in the initial wavelength if the initial amplitude is smaller than the critical amplitude; and the growth behavior is opposite for the unstable case when the initial amplitude is larger than the critical amplitude.The initial thickness of plate is also an important factor for perturbation growth，and there is a critical thickness related to initial perturbation characteristics. In the preliminary stage of perturbation growth，the strength of material has no influence on the perturbation amplitude growth，and the yield strength of material can greatly reduce Rayleigh-Taylor growth rate at the later stage of Rayleigh-Taylor instability growth; and the effect of shear module can be neglectful to a certain extent in the period of perturbation growth.

Transmission Characteristics of Impact Load of Flying Debris at Epoxy Resin/printed Circuit Board/epoxy Resin Interfaces

XU Xiao， JIN Lei， HUANG Shaling， GAO Shiqiao， ZHANG Husheng

2020, 41(9):  1817-1825.  doi:10.3969/j.issn.1000-1093.2020.09.014

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The transmission characteristics of in-plane impact load of flying debris at the typical interfaces in a encapsulated circuit system are studied to improve the impact resistance of missile-borne circuit system. The transfer process of impact load at epoxy resin/PCB/epoxy resin interfaces is analyzed from the perspective of experiment， theory and simulation.The variation processes of impact load at the interfaces are measured using the multiple embedded stress sensors.Depending on the theory of stress wave propagation，the incident，reflective and transmission characteristics of shock wave at those interfaces are analyzed，and the attenuation characteristics of shock wave in the viscous medium are considered. The approximate theoretical results of transmission of impact load at the interfaces were obtained through calculation.The experimental results were verified by numerical simulation，combined with the results in Ref.［16］. The theoretical and simulated results agreed well with the measured data.The results show that the overload at the back of PCB is smaller along the direction of stress wave propagation.

Smeared Spectrum Jamming Suppression Algorithm Based on Multiple Orders 2D-FRFT

ZHANG Liang， WANG Guohong， ZHANG Xiangyu， LI Siwen

2020, 41(9):  1826-1836.  doi:10.3969/j.issn.1000-1093.2020.09.015

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The existing smeared spectrum (SMSP) jamming suppression algorithms are all aimed at the echo signal within a pulse repetition interval (PRI). Those algorithms need to suppress the SMSP jamming of each PRI when dealing with the whole echo within a coherent processing interval (CPI). For linear frequency modulation pulse Doppler radar countering stand-off SMSP jamming, a jamming suppression algorithm based on multiple orders two-dimensional fractional Fourier transform(2D-FRFT) is proposed to process the echo within a CPI received by radar. The fractional characteristics of the jammed echo are analyzed. On this basis，the critical motion parameters of real target and jammer in the appearance of fractional migration are studied using the sampling-type DFRFT. The 2D fractional coverage windows are designed to remove the SMSP jamming. The simulated results show that the proposed algorithm can be used to simultaneously achieve the jamming suppression and target detection by processing a CPI echo without suppressing the SMSP jamming of each PRI.

Implementation and Performance of FPGA-based Multi-priority Optimized CSMA in Ad Hoc Network

DING Hongwei， LU Xu， YANG Zhijun， BAO Liyong， LIU Qianlin

2020, 41(9):  1837-1847.  doi:10.3969/j.issn.1000-1093.2020.09.016

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The ad hoc network is widely used in military field and some extreme natural environments because it has the characteristics of not needing to set up network facilities and strong invulnerability，etc. Random multiple access control protocol plays an important role of media access control layer in the ad hoc network，and the delay and reliability of multiple access protocol are the key factors that restrict the transmission quality. In order to solve the two key problems，the traditional random multiple access control protocol is improved，and an optimized three-dimensional probability carrier sense multiple access (CSMA) protocol model is proposed，which guarantees higher throughput and further improves the reliability of the protocol in the case of high arrival rate. At the same time，the different priorities are set for different sending nodes to achieve the purpose of differentiating services and enhance the utilization of channel resources. The results show that, compared with the traditional 1-persistent CSMA protocol，the optimized three-dimensional probability CSMA reduces the delay and increases the maximum throughput by 24.34%. According to the principle of the protocol，a hardware system of the multi-priority optimized three-dimensional probability CSMA based on field programmable gate array was designed.

Self-repair Strategy of Wire Fault Tolerance in Embryonic Electronic Array

WANG Liwei， CAI Jinyan， XU Chengzhi， ZHU Sai

2020, 41(9):  1848-1860.  doi:10.3969/j.issn.1000-1093.2020.09.017

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Most self-repair strategies of embryonic electronic arrays (EEA) only consider how to tolerate the faults from embryonic electronic cells. However, there is little concern about how to tolerate the faults from interconnect wires. The interconnect wires among cells are the data transmission channels. If there is any fault in the interconnect wires，the embryonic electronic array cannot work. A new self-repair strategy， the hybrid elimination strategy，is proposed. The hybrid elimination strategy can tolerate not only the fault of interconnect wires but also the fault of embryonic electronic cell. The effect of interconnect wires failure on the reliability of embryonic electronic array is analyzed. The structure of embryonic electronic array is designed based on the hybrid elimination strategy. The effectiveness of hybrid elimination strategy was verified by simulating and analyzing a 4-bit multiplier with a 7×6 embryonic electronic array. The simulated result shows that the hybrid elimination strategy can effectively tolerate the faults from cells and interconnect wires. The analyzed results of hardware resource consumption and reliability show that，for the hybrid elimination strategy，the hardware resource consumed by the part which is used to tolerate the fault of interconnect wires is very little，and the hardware resource consumption of the hybrid elimination strategy is acceptable；the hybrid elimination strategy has a better reliability performance than those of column elimination strategy and cell elimination strategy about imperfect interconnect wires，especially for the reliability of embryonic electronic array with large amount of interconnect wires.

A SAR Target Recognition Algorithm Based on Guided Filter Reconstruction and Denoising Sparse Autoencoder

WANG Jian， QIN Chunxia， YANG Ke， REN Ping

2020, 41(9):  1861-1870.  doi:10.3969/j.issn.1000-1093.2020.09.018

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The existing synthetic aperture radar（SAR） target recognition algorithms have the poor generalization ability and high complexity. For the problems above，an algorithm based on the guided filter reconstruction and denoising sparse autoencoder is proposed. The guided filter reconstruction algorithm with two-scale image fusion preprocessing of SAR image is used to generate an one-dimensional image vector and normalizate it in order to reduce the dimension of output feature of the image and increase the speed of preprocessing. The algorithm would extract and recognize the low-dimensional features of images by reducing the hidden layer neurons of the denoising autoencoder， which can effectively reduce the complexity of the algorithm. The Softmax classifier is used for classifying. The experimental results show that the SAR target recognition algorithm based on the guided filter reconstruction and denoising sparse autoencoder can not only improve the target recognition performance and generalization ability， but also reduce the number of hidden layer neurons in the autoencoder and the computational complexity, and the network structure has also been improved and optimized as well.

Multiple Line Spectrum Interference Suppression-based Line Spectrum Detection of Moving Airborne Sound Source Underwater

LIU Kaiyue， PENG Zhaohui， ZHANG Lingshan， WANG Guangxu， LI Shenghao

2020, 41(9):  1871-1879.  doi:10.3969/j.issn.1000-1093.2020.09.019

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A robust and reliable detection method based on multiple line spectrum interference suppression is proposed to solve the problem of strong underwater interference in the detection of moving airborne sound source underwater.The line spectrum of the received sound field is extracted，and then the spatial spectrum energy of each source being mainly from the contribution of one line spectrum is limited to suppress the interference energy of multiple line spectrum. Finally，the direction estimation is obtained by synthesizing all the line spectrum contributions. The effectiveness of the proposed method is verified through two underwater-to-air detection experiments. The results show that the method can be used to detect the line spectrum of moving airborne sound source underwater in the low SNR and multiple interferences environment，and effectively suppress the interference with the same or very similar frequency.

Detection Method for Underwater Slow Moving Targets Based on Frequency-wavenumber Spectrum Analysis in ReverberationEnvironment

XU Yanfeng, PAN Xiefan, LIU Benqi

2020, 41(9):  1880-1886.  doi:10.3969/j.issn.1000-1093.2020.09.020

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For the problem that detected signals of underwater slow moving targets are usually immersed by random noise and reverberation, this paper presents a detection method based on frequency-wavenumber (FK) spectrum analysis. FK analysis is like a velocity filter, in which the signals of targets and reverberation have different distributions. According to this feature, the information in FK spectrum obtained through two-dimensional Fourier transform is extracted by Radon transform. A low dimensional feature space is constructed based on the FK spectrum, and the supported vector machine is used to recognize the signals of moving targets and reverberation. Additionally, the signals of moving targets are filtered according to the slope of FK spectrum. The proposed method is more effective than traditional method because it is “classify before detect” without beamforming. The feasibility of the method is verified using sea trial data. Target signal is successfully extracted from the strong reverberation signal, and the obtained gain is 3 dB. The result shows that the proposed method has ability to extract slow moving target signal critically disturbed by reverberation.

Improving the Detection Accuracy of Wake Targets by Improved One-class Support Vector Machine

WANG Cheng， WU Yan， YANG Tingfei

2020, 41(9):  1887-1893.  doi:10.3969/j.issn.1000-1093.2020.09.021

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A turbulent area containing a large number of bubbles is generated at the tail of the ship during the voyage. The ship can be effectively tracked by the acoustic detection of wake. An improved one-class support vector machine (SVM) algorithm is proposed，which uses the echo signal in the wake-free case as an optimal classifier for the training set for judging the wake echo signal mode. The echo signal is denoised，and then an adaptive feature extraction method is proposed to process the echo signal; a dual-threshold one-class SVM with two-layer decision boundary is used for wake detection by using feature extraction as input. The simulated results show that，compared with the conventional one-class support vector machine，the improved algorithm can be used to improve the detection accuracy which is up to 96.27% under different SNRs.

CNN-based Real-time Prediction Method of Flight Trajectory of Unmanned Combat Aerial Vehicle

ZHANG Hongpeng， HUANG Changqiang， TANG Shangqin， XUAN Yongbo

2020, 41(9):  1894-1903.  doi:10.3969/j.issn.1000-1093.2020.09.022

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Trajectory prediction is part of air combat technology，and the predictors can select a more predictable maneuvering considerion of trajectory prediction results. A convolution neural network predicting method is proposed to obtain the position of unmanned combat aerial vehicle in a future time quickly and accurately. An improved model for limiting the angular velocity is presented since the original dynamic model can not correctly simulate the somersault maneuvering with roll angle deviation. The improved model is used for flight simulation under different conditions，and a large number of trajectory samples are obtained. The convolution neural networks with different layer number and convolution kernel number is trained and tested，and the network with the smallest prediction error is selected. Operational speed and error of the proposed method are compared with those of long short term memory neural network，recurrent neural network and fully connected neural network. The results show that the average prediction error of the proposed method is about 4.2 m on x axis，8.0 m on y axis and 19.5 m on z axis after 0.25 s without increasing operational time，and the errors are all smaller than those of the other methods.

Effect of Thermo-mechanical Treatment on the Microstructure and Mechanical Properties of a Medium Carbon Cr-Ni-W-Mo Steel

LIANG Jiaxin， WANG Yingchun， CHENG Xingwang， LI Zhuang， LI Shukui

2020, 41(9):  1904-1912.  doi:10.3969/j.issn.1000-1093.2020.09.023

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In order to further improve the strength and ductility of the medium carbon Cr-Ni-W-Mo steel， the effect of thermo-mechanical treatment (TMT)，which was conducted at 700 ℃ with deformation from 20% to 50%，on the microstructure evolution and mechanical properties of medium carbon Cr-Ni-W-Mo steel was analyzed by scanning electron microscopy (SEM)，transmission electron microscopy(TEM)，electron backscattered diffraction (EBSD) and tensile test. The results show that the microstructures of steel after TMT processing contain the complex phases with tempered martensite，lower bainite and retained austenite.The fractions of lower bainite and retained austenite，and the dislocation density increase together with the refinement of martensite lath with the deformation increasing from 20% to 50%. Due to the coupling effects of phase transformation strengthening，fine grain strengthening and dislocation strengthening，the strength and ductility of steel are improved simultaneously with the increase in deformation. The steel processed by TMT with deformation of 50% has high strength and good ductility，and its yield strength，ultimate strength and elongation are 1 733 MPa， 2 243 MPa and 12.66%，respectively， which are improved by 28.18%，12.88% and 50.35% than those of the steel processed by conventional heat treatment，respectively.

Heat Flow Simulation Irradiation System for Military Aircraft

WANG Danyi， JIANG Shanping， YANG Linhua

2020, 41(9):  1913-1920.  doi:10.3969/j.issn.1000-1093.2020.09.024

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The demand for environmental simulation of fighter or military aircraft operation is gradually increasing with the increasing demand for fighters and military aircrafts in China. A high power irradiated heat flow simulation system is proposed to meet the requirements of military aircraft cabin lighting simulation and improve the accuracy of heat flow simulation. The system can simulate the sunlight environment at different altitudes. It can simulate the process of icing and deicing flight together with the use of low temperature cooling and air pressure regulating system in environment simulation cabin. At the same time， the visual load test and visual efficacy test in different lighting environment can be carried out to simulate the impact of lighting on the pilot during flight. Through design and simulation，it is found that the radiation area of heat flux simulation irradiation system is 1 500 mm×3 500 mm， the maximum radiation energy can reach 1.89 sc(1 sc=1 353 W/m²) within the working distance of 1 000 mm， and the radiation uniformity can reach±12.2%. An experimental system was measured. The measured maximum irradiation energy can reach 1.80 sc， and the irradiation uniformity can reach±13.3%，which is close to the simulated results，verifying the accuracy and reliability of the radiation system. In addition，in order to meet the common needs of military aircraft cockpit，the low-pressure environment test of a single lamp was carried out. The test results show that the single lamp structure of system can meet the work in the low-pressure environment. The following special environment test of the whole heat flow simulation irradiation system can be further carried out.