Table of Content

31 March 2021, Volume 42 Issue 3

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Contents

2021, 42(3):  0. 

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Paper

Longitudinal and Vertical Coupled Dynamic Model and Power Characteristics of Tracked Vehicle

LI Chunming, WU Wei, GUO Zhiqiang, YUAN Shihua, CHEN Si

2021, 42(3):  449-458.  doi:10.3969/j.issn.1000-1093.2021.03.001

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The dynamics of tracked vehicle in the off-road condition is the basis of the prediction of the off-road driving ability. A longitudinal and vertical coupled dynamic modeling method of tracked vehicle is presented，in which the coupling effect of longitudinal and vertical motion of high speed tracked vehicle is considered. A vehicle coupling dynamic model is established. The driving performance of vehicle on the typical road was simulated and verified in the real vehicle test. On this basis，the power flow characteristics of the tracked vehicle were analyzed. The simulated results indicate that the proposed model can be used to calculate the influence of the different road conditions on the vehicle driving performance. In the off-road condition，the road roughness makes the body vertical，pitching and other movements consume part of the power，and then have a certain impact on the speed of the vehicle. The instantaneous non-driving power of the tracked vehicle fluctuates widely. With the deterioration in the road conditions and the increase in speed，the ratio of non-driving power to total input power increases.The demand for the total power increases，which limits the effective use of the driving power.The results can be used for the dynamic model construction and the power flow analysis of high-speed tracked vehicles.

Control Method for AMT Shifting of a Shift-by-wire Bilateral Electric Drive Tracked Vehicle

ZHAO Yidong, CHEN Huiyan, HU Jiaming

2021, 42(3):  459-467.  doi:10.3969/j.issn.1000-1093.2021.03.002

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A suitable simplified shifting control method is designed for using automated mechanical transmission(AMT) to realize the shifting of bilateral electric drive tracked vehicle. AMT is a clutchless two-speed planetary gearbox. Gear shifting is electric and driven by wire. During synchronizing phase, the speed of input shaft is roughly synchronized using traction motor; during gear engaging phase, the accurate speed matching is supposed to be ensured by the synchronizer. Two gearboxes are used for vehicle shifting. Their shifting processes start simultaneously and last independently. Upshifting and downshifting are tested for many times when driving forwardly on soft soil land. Test results show that shifting is executed successfully and efficiently; the synchronizers hardly lock to cause wear; upshifting needs longer time than downshifting as vehicle speed remains unchanged; upshifting and downshifting times both tend to be longer as vehicle speed becomes higher; two gearboxes accomplish shifting almost simultaneously; while shifting, the environment mainly causes vehicle speed reduction, and hardly causes the speed difference of vehicle track.

Characteristics of Electric Variable Valve Timing Mechanism of Diesel Engine

YU Fei， LIU Bolan， YAN Chao， HAN Yaohui， WANG Wentai

2021, 42(3):  468-477.  doi:10.3969/j.issn.1000-1093.2021.03.003

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Low compression ratio Miller cycle in highly-intensified diesel engine can effectively control the burst pressure. The increase in the late intake valve closing (LIVC) timing brings reduction in the effective compression ratio, which leads to difficulty in starting.The application of variable valve timing technology can effectively take into account the relationship between the burst pressure and the starting of diesel engine. A simulation experimental device of electric variable valve timing mechanism was designed. The electric variable valve timing mechanism is composed of brushless DC motor, NN small tooth number difference deceleration mechanism and related control system. It can achieve high response phase adjustment with an adjustment accuracy of ±0.116°. According to the characteristics of the mechanism, a mathematical model of the system is established, the characteristics of the motor are checked, the basic adjustment characteristics are analyzed, and the initial PID parameters are optimized. A bench test study was carried out to verify the basic timing adjustment characteristics, starting adjustment characteristics, and voltage influence characteristics. The research results show that the electric variable valve timing mechanism can achieve basic timing angle adjustment,the maximum late closing angle can be reached within 5s under starting condition and the reduction in battery voltage has an effect on the advance in phase angle, but does not affect the delay of phase angle.

Multi-field Stress Response of Centrifugal Compressor Impeller in Variable Altitude Environment

HONG Zhouzhensen, ZHANG Hong, MA Chaochen, WU Xintao

2021, 42(3):  478-486.  doi:10.3969/j.issn.1000-1093.2021.03.004

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The change laws of multi-field load and stress response of turbocharger centrifugal compressor impeller are studied for the static strength failure of impeller in a variable altitude environment. The unidirectional steady-state fluid-structure interaction method is used to calculate the single-field stress and multi-field coupling stress of impeller under aerodynamic, thermal, and centrifugal loads. The results indicate that, when only the inlet pressure and inlet temperature are changed according to the altitude without changing the true flow rate and the true revolving speed, the flow angle at impeller inlet increases with altitude, resulting in a larger static pressure difference on the leading edge of the long blade; and the maximum aerodynamic stress is then transferred from the trailing edge to the leading edge of the long blade. In the same case, the thermal load, thermal stress and maximum coupling stress decrease with altitude. When the working conditions of the supercharged engine remain unchanged, with the increase in altitude， the absolute changes in the aerodynamic and thermal stresses of the impeller are small, and the increase in the compressor speed brings a large increase in the centrifugal stress, which in turn leads to an increase in coupling stress.

Prediction of Moisture Absorption-creep Coupling Behavior of Box-type Composite Directors for Multiple Launch Rocket System under Long-term Stacking Storage

SUN Tongsheng, ZHU Junyao, YU Cungui, YANG Wenchao, XU Qiang

2021, 42(3):  487-498.  doi:10.3969/j.issn.1000-1093.2021.03.005

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In order to investigate the moisture absorption-creep coupling behavior during long-term stacking storage of box-type composite directors for multiple launch rocket systems, a three-dimensional orthotropic nonlinear creep constitutive model considering moisture effect is derived by introducing the moisture shift factor into the Schapery's nonlinear equation. The E-fiberglass/6509 epoxy resin composite laminates were prepared, and the moisture absorption test, static mechanical performance test and short-term creep-recovery test were carried out to obtain the hygroscopic parameters and the moisture- and stress-dependent nonlinear creep parameters. Finite element method was used to establish a numerical model of coupled moisture diffusion-nonlinear creep analysis. The creep deformation of composite directors after 15 years of storage was predicted. The calculated results show that the moisture diffuses to the inner surface of director after one year of storage in the general military warehouse and reaches the quasi-equilibrium uptake state after eight years. The maximum residual deformations of all 20 directors take place between the second and third positioning rings, and are approximately distributed in a saddle shape in three-dimensional space. The residual deformations of the directors between upper and lower rows are the largest with a maximum value of 0.38 mm, while those of the directors between left and right columns are the smallest with a minimum value of 0.33 mm.

Echo Characteristics of Continuous Wave Laser Fuze in Aerosol Environment

SONG Chengtian, ZHANG Yaoyan, LIU Qiang, LIU Bohu

2021, 42(3):  499-510.  doi:10.3969/j.issn.1000-1093.2021.03.006

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The laser fuze has the advantages of high ranging accuracy and resistance to electromagnetic interference, but it is susceptible to interference from aerosol particles such as smoke and dust. The echo signal characteristics of continuous wave (CW) laser fuze under aerosol interference were studied based on Monte Carlo simulation method. A CW laser echo signal model under the action of aerosol particles is constructed, which includes backscattering signal, target signal scattered by particles and target echo signal. The extinction coefficient and scattering coefficient of aerosol in the model could vary dynamically with the position of photons, the aerosol concentration distribution, and the aerosol particle size distribution. The echo signal in aerosol environment was simulated. The relationship among the characteristics of signal time frequency domain, signal-to-noise ratio (SNR) and laser wavelength, aerosol particle sizes at different aerosol concentrations was analyzed. Simulated and experimental results show that the echo signal characteristics are related to the concentration of aerosol. At low aerosol concentration, the spectral peak of echo signal is concentrated at the frequency related to the target distance, and there is no spectral peak of interference. When the aerosol concentration exceeds the moderate condition, both the target spectrum peak and the interference spectrum peak exist. And when the heavy interference is reached, the interference spectrum peak may be stronger than the target spectrum peak. The SNR decreases with the increase in aerosol concentration. For the laser with the wavelength range of 400-1 100 nm, when the particle size distribution is 20-100 μm, the SNR is relatively high.

Experimental Method for Pressure-coupled Response of Solid Propellants Based on Rotary Valve

XI Yunzhi, LI Junwei, CHEN Xueli, HAN Lei, WANG Ningfei

2021, 42(3):  511-520.  doi:10.3969/j.issn.1000-1093.2021.03.007

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For the combustion instability of solid motors, an experimental method of pressure-coupled response of solid propellant based on rotary valve is proposed, and a rotary valve experimental system for cold gas and solid propellant ignition experiments is designed. In the cold gas experiments and theoretical calculations of 23 Hz, 46 Hz and 69 Hz oscillation frequencies, the maximum error of the two methods is 4.35%, which verifies the effectiveness of the circular grating positioning assembly to obtain the secondary exhaust passage area and pressure delay time of the rotary valve. Five ignition experiments of solid propellant at 23 Hz, 46 Hz, 69 Hz, 115 Hz and 138 Hz oscillation frequencies were carried out. The results show that the mean pressure of the combustion chamber is affected by the oscillation frequency, which is reduced from 2.88 MPa at 23 Hz to 2.523 MPa at 138 Hz. The pressure-coupled response function of the measured solid propellant is less affected by the oscillation frequency, which is maintained at 0.80±0.13. The rotary valve scheme is feasible and reliable.

Adaptive Fault-tolerant Control of Hypersonic Vehicles

YUE Bin, MA Wen, HU Weijun

2021, 42(3):  521-529.  doi:10.3969/j.issn.1000-1093.2021.03.008

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An adaptive fault-tolerant control strategy is proposed to solve the problems of multiple disturbances and actuator failures in hypersonic vehicle. An aircraft model with multiple disturbances and actuator failures is established. An adaptive reconfigurable compound controller was designed, which can compensate the influence of actuator failure on attitude control system by dynamically adjusting controller parameters. The designed controller has excellent control performance by estimating the upper bound of the multiple disturbances and using the hyperbolic tangent function to compensate the influence of the multiple disturbances when the multiple disturbances and actuator failures exist simultaneously. For the difficult problem of solving the micro-components of virtual control instructions, the first-order filter is used to filter the virtual control instructions in the process of controller design, thus avoiding the complicated derivation process. The asymptotic stability of the controller is proved by using Lyapunov method, and the simulated results show the feasibility and effectiveness of the proposed method.

Effects of High Performance Concrete and High Strength Steel on the Blast Response of Steel Reinforced Concrete Columns

YAN Junbo, LIU Yan, LI Yafei, XU Zixi, HUANG Fenglei

2021, 42(3):  530-544.  doi:10.3969/j.issn.1000-1093.2021.03.009

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A numerical model of the reinforced concrete (RC) columns was developed using software LS-DYNA.In the numerical model，the smooth particle hydrodynamics (SPH) method is used，and the spalling effect and strain rate effect are considered. The finite element model is valiated through the experimental data. A parametric study is further carried out to examine the effects of ultra-high performance concrete(UHPC)，high strength concrete(HSC) and high strength steel(HSS) on the blast resistance of RC columns. The results show that， compared with normal strength concrete column (30 MPa compressive resistance) and high strength concrete column(80 MPa compressive resistance)，the blast resistance of UHPC column (140 MPa compressive resistance) is increased by ten times under same scaled distance of 0.8 m/kg^1/3. However，HSS results in more brittle damage in UHPC columns. The damage mode of RC columns changes from flexure to shear.

A Video-based Prediction Algorithm for Armored Vehicle and Aircraft Detection/tracking and Trajectory

ZHANG Yongmei， LAI Yuping， MA Jianzhe， FENG Chao， SHU Jie

2021, 42(3):  545-554.  doi:10.3969/j.issn.1000-1093.2021.03.010

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To solve the problem of easily losing the targets when tracking multiple targets by the current video target tracking algorithms，an improved tracking-learning-detection (TLD) algorithm is presented for multi-target detection and tracking by taking armored vehicles and aircrafts in videos as the research objects.For the lost targets，the trajectories of typical targets in video are tracked by using the prediction function of Kalman filtering algorithm，and the tracked trajectories are used to compensate for the lost parts of TLD algorithm so as to obtain the complete trajectories of typical targets in videos，which is beneficial to improve the accuracy of video multi-target tracking.For the poorer accuracy of the existing trajectory prediction methods，a video target trajectory prediction algorithm based on social long short term memory (Social-LSTM) network is proposed. The algorithm integrates the contextual environment information and the interaction relationship among multiple target trajectories into Social-LSTM network and predicts the trajectories of the typical targets to be detected. Simulation experimental results show the trajectory prediction algorithm is superior to the traditional LSTM algorithm，hidden Markov model (HMM) algorithm，and Gaussian mixture model (GMM) algorithm，which is helpful to improve the accuracy of trajectory prediction for typical video targets.

Improved Adaptive Hatch Filter Algorithm Based on Code-carrier Divergence

HU Jie， ZHANG Lin， ZHU Yixian， ZHOU Ling

2021, 42(3):  555-562.  doi:10.3969/j.issn.1000-1093.2021.03.011

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The smoothing accuracy of carrier-phase smoothing pseudorange in single-frequency ground-based augmentation system (GBAS) is easily affected by the ionospheric delay and pseudorange measurement noises. The influence of code-carrier divergence of satellite signal on the smoothing accuracy of Hatch filter is analyzed, and an improved adaptive Hatch filter algorithm based on code-carrier divergence is proposed. The code-minus-carrier is computed using pseudorange and carrier-phase measurements, and its first-order linear model is established. The ionospheric delay rate is estimated by using the least square method. Given the estimated ionospheric delay rate, the pseudorange measurement noise can be separated. A function model between the root mean square of smoothed pseudorange and the ionospheric delay rate, the standard deviation of pseudorange measurement noise and the smoothing time of Hatch filter is established, from which the optimal smoothing time of Hatch filter can be calculated. The verification experiments were carried out by using GBAS prototype. The experimental results show that the adaptive Hatch filter is able to calculate the optimal smoothing time of filter based on the real-time ionospheric delay rate and the standard deviation of pseudorange measurement noise. Compared with the traditional fixed smoothing time algorithm, the maximum position accuracy of airborne differential positioning is improved by 53.19 percent by using the adaptive Hatch filter algorithm, which verifies the effectiveness of the proposed algorithm.

Optimization Approach of the Deployment Network for Multistatic Radar

LI Haipeng， FENG Dazheng， ZHOU Yongwei， DONG Pukao

2021, 42(3):  563-571.  doi:10.3969/j.issn.1000-1093.2021.03.012

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An optimization approach based on minimum deployment cost is proposed to solve the cost-effectiveness problem of deployment network for multistatic radar. The width equipartition barrier is adopted in the deployment strategy，and an optimal model is proposed based on the optimum condition of one deployment line. In order to solve the optimal model，the exhaustive algorithm is introduced to determine the deployment parameters for every possible barrier width. Considering that the unit cost of a transmitter is greater than that of a receiver，the optimum deployment cost and corresponding deployment parameters can be found by minimizing the deployment cost. To decrease the calculated amount of the algorithm， the search scope of exhaustive search is reduced by theoretical demonstration. Simulated results indicate that， compared with the existing similar approach， the proposed approach is used to reduce the deployment cost， usage quantity of transmitters and calculated mount， and make engineering more economical and keep safe in electronic warfare.

Design of Off-axis Paraboloid Reflection Optical System of Color Temperature Star Simulator

LIU Huan， WANG Chunyan， WANG Zhiqiang， SUN Hao， ZHAO Yiwu

2021, 42(3):  572-580.  doi:10.3969/j.issn.1000-1093.2021.03.013

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In order to test the tracking ability of star sensor to a starlight at infinity in the laboratory, an optical system is designed to simulate the starlight color temperature at infinity by using a broad spectrum color temperature source through a collimator. In this system, the aperture off-axis method is adopted to avoid the phenomenon of shading ratio of the coaxial system, the paraboloid of the primary mirror makes the image quality of the system better, and the wide spectrum anastigmatism problem of the transmission receiver is solved by combining with the wedge-shaped semi-inverse semi-permeable secondary mirror. The design index requirements are that the working band is 400-900 nm, the entrance pupil diameter is 300 mm, the focal length is 3 150 mm, and the field-of-view angle is 0.05°. The actual test results show that, in the case of the secondary mirror without aspheric surface, the optical system can achieve the index requirements,i.e., the modulation transfer functions of both the reflection end and the transmission end are close to the diffraction limit, the RMS value of wave aberration of each field of view is better than λ /30, and the parallelism of the emitted light is better than 1″.

Effectual Decoy Airspace and Application of Natural Features Used as False Targets

SUN Chunsheng， ZHANG Shuang， ZHANG Xiaohui， TANG Yong

2021, 42(3):  581-587.  doi:10.3969/j.issn.1000-1093.2021.03.014

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For the application of natural features as false targets in laser decoy jamming，a calculation method for effectual decoy airspace is presented， and the proposal of typical natural features used as false targets was given.An analytic model of effectual decoy airspace is established，in which diffuse reflection false target is used as reference object.The effectual decoy airspace of typical natural features such as vegetation，gravel and soil is calculated based on the proposed model.Some suggestions on how to select the type，location and slope of natural features used as false targets are presented according to the distribution of effectual decoy airspace.The results show that the effectual decoy airspaces of gravel，soil and vegetation targets decrease in turn and are generally smaller than that of standard diffuse reflector.With the growth of laser beam incident angle， the effectual decoy airspace of natural features used as false targets decreases， and there is different degree of mirror shifting. When the natural features are selected as laser false targets， the gravel and soil targets should be preferentially selected， and the same type of natural features at lower altitudes provide better decoy effect. In addition，the selection of slope gradient should ensure that the cheating airspace formed by laser decoy on the slope covers the range of laser threat.

Motion Error Estimation Algorithm Based on DPC and INS for Synthetic Aperture Sonar

ZHANG Yu， WANG Peng， LIU Jiyuan， ZHONG Rongxing， WEI Linzhe， CHI Cheng

2021, 42(3):  588-597.  doi:10.3969/j.issn.1000-1093.2021.03.015

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A displaced phase center (DPC) aided inertial navigation system (INS) combination method is proposed to reduce the complexity of motion measurement system and improve the estimation accuracy of motion error of synthetic aperture sonar. A multiple-receiver spatial mutual correlation matrix is built to estimate the forward velocity of sonar in reference to DPC method, and then three-dimensional velocity can be calculated with the attitude angle from INS. Kalman filter is applied to fuse data from DPC and INS, which outputs the optimal estimation of the velocity. Finally, the motion error is calculated with the integral of the velocity. The field experimental results show that DPC aided INS combination method, in comparison to DPC algorithm, increases more motion details that the velocity curve gets sharper, which means a good performance in the estimation of velocity. After motion compensation, the image quality gets improved with better focus and less ghosting.

Ballistic Resistance of Al-Mg-Al Light Metal Layered Armor Plate

GUO Denggang, ZHOU Qiang, LIU Rui, CHEN Pengwan

2021, 42(3):  598-606.  doi:10.3969/j.issn.1000-1093.2021.03.016

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The feasibility of Al-Mg composite plate used for armor protection is studied to compare the shell-proof performances of Al-Mg composite plate and aluminum alloy plate with uniform thickness. The magnesium alloy is used to replace partial Al alloy to lower the weight of Al alloy armor, and the explosive welding method is applied to fabricate the Al-Mg-Al layered composite plate. The ballistic resistance and corresponding mechanism of Al-Mg-Al layered composite plate were analyzed through the experimental measurement and numerical simulation, respectively. The layered armor plate was compared with AZ31 magnesium alloy plate, 2024 aluminum alloy plate and stacked Al-Mg-Al plates by using the residual depth-of-penetration method. The penetration of the bullet on different types of targets was simulated to verify the experimental results, and the effect of interfacial bonding strength on the ballistic resistance of layered composite plate was further studied. The results show that the ballistic performance of Al-Mg-Al welded plate is close to that of 2024 aluminum alloy plate, but it is 23% lighter than the 2024 aluminum alloy plate under the condition of equal plate thickness. The interfacial bonding strength can improve the ballistic resistance of layered composite plate. With the increase in interfacial bonding strength, the anti-ballistic capability of target plate is enhanced through the coordination deformation of all the layers.

Dynamic Expansion and Fragmentation of Toughened Ceramic Ring Based on Discrete Element Method

REN Huilan, ZHAO Hanqing, LI Wei, NING Jianguo

2021, 42(3):  607-616.  doi:10.3969/j.issn.1000-1093.2021.03.017

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The dynamic expansion fragmentation of ceramic is numerically simulated to study the impact tensile fracture of ceramic with high strength and brittleness. The free expansion motion of toughened ceramic ring at high strain rate is studied using flat-joint contact model based on the discrete element method, from which the variation laws of particle motion velocity and system energy during the expansion and fragmentation process of ring are obtained. The results show that, before the ring fracture, the radial velocity of inner particles presents an increasing jump in the middle layer, while the radial velocity of outer particles presents a decreasing jump. The velocity jump is related to the rigidity of ceramic ring, but not to the initial loading velocity, at the moment of ring fracture, the release of strain energy is accompanied by the formation of unloading wave in the ring. Due to this fact, the radial velocity of outer particles presents an increasing jump, while the radial velocity of inner particles presents a decreasing jump. This velocity jump phenomenon is helpful to determine the initial brittle fracture time of the ring in the experiment; the normalized size of ceramic fragments decreases with the increase in normalized strain rate, which is in good agreement with the theoretical model in Ref.［17-18］.

Background Selection Method of Optical Camouflage Effect Evaluation Based on Color Clustering

YU Songlin， CHEN Yuhua， HE Hu， WANG Jijun， LI Yan

2021, 42(3):  617-624.  doi:10.3969/j.issn.1000-1093.2021.03.018

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In the camouflage effect evaluation of single target based on optical images，a large deviation in the evaluation results may be caused by taking the 8-neighborhood image of the target region as the background region when the target is near the boundary between different background areas with large contrast.To solve this problem，a background selection method based on color clustering is proposed.The color classes that are not included in the target neighborhood are removed from the color clustered 8-neighborhood image by the proposed method，and then the target region is subtracted to get the selected background. Experimental results show that the irrelevant background regions can be effectively removed when the image is clustered by 4-6 color cluster centers，so as to enhance the objectivity and accuracy of camouflage effect evaluation. The proposed method is suitable for different target location relationships.

Damage Effect of Shallow Buried Civil Air Defense Engineering Structures under Nearby Blast Loading

LIU Fei， WANG Huiming， YAN Luhui， LI Huanqiu

2021, 42(3):  625-632.  doi:10.3969/j.issn.1000-1093.2021.03.019

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The semi-buried and fully-buried civil defense engineering structures under the conditions of different blast distances and charge masses were experimentally studied to investigate the damage effects of civil defense engineering structure under blast loading. The dynamic response and damage characteristics of civil defense engineering structures are analyzed through 11 batches of blast experiments with a large scale ratio of 1/3.The results show that the overpressure generated by blast shock wave on the external wall is related to the stiffness of wall panel，and the design load of external wall structure should be the load at the maximum stress position of wall surface.The damage effects caused by the contact blast near the outer wall of semi-buried basement and the ground-shock explosion near the fully-buried basement are related to the overpressure on the wall surface，and also closely related to the duration of explosion，surrounding media，and structures in the medium.

The Strategy of Grinding Dimpled Surface for Reducing Friction Force by Grinding Wheel with Ordered Abrasive Grain Clusters

LI Xingshan， L Yushan， WANG Yuchen

2021, 42(3):  633-639.  doi:10.3969/j.issn.1000-1093.2021.03.020

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Structured surfaces play an important role in reducing the friction or dragging force of mechanical parts. In order to obtain an efficient grinding method for structured friction-reducing surfaces，a strategy for grinding the dimpled surface for friction-reducing by the grinding wheel with ordered embedded abrasive grain clusters was proposed based on the design theory of ordered arrangement of abrasive grains in grinding wheel. The arrangement design theory of the abrasive grain clusters on the grinding wheel is studied，and the relationships between the arrangement parameters of the grinding wheel and the dimpled surface of workpiece are analyzed.The grinding parameter conditions to realize the arrangement of the dimples and the relationship between the dimples and the geometry of abrasive grain clusters are discussed.The grinding parameter conditions to realize the arrangement of the dimples are discussed. The design theory of the ordered grinding wheel of abrasive grain clusters is studied，and the relationship between the arrangement parameters of the abrasive grain clusters of grinding wheel and the the dimpled surface of workpiece is analyzed. The grinding morphology and grinding mechanism of structured dimpled surface were verified through grinding experiment. The results show that the ordered grinding wheel with embedded abrasive grain clusters can be used to grind a structured dimpled surface with phyllotactic pattern，staggered pattern and array pattern.The arrangement and shape of the grinding structured dimpled surface depends on the layout design parameters of grinding wheel，the geometric shape parameters of abrasive grain clusters，and the choice of grinding parameters.

A Temperature Measuring Method for Explosive Temperature Field Based on High-speed Imaging Technology

XU Renhan， ZHOU Yijie， DI Chang'an

2021, 42(3):  640-647.  doi:10.3969/j.issn.1000-1093.2021.03.021

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A temperature measuring method for explosive temperature field based on high-speed imaging technology is proposed for the fast change, wide range, high temperature and difficult measurement of explosive temperature field. Based on the principle of radiation, a temperature measuring model of high-speed imaging system is deduced. The corresponding relationship between gray value of high-speed camera image and temperature of explosion is established, the temperature measuring range can be controlled by controlling the exposure time and transmittance of the high-speed imaging system. A high-speed imaging explosive temperature field measuring system was build, and the least square method was used to calibrate the system. The calibrated results show that the average error of the proposed method is 0.74% in the temperature range of 2 200-2 900 ℃ and 1.95% in the temperature range of 1 850- 2 350 ℃, which can meet the measuring requirements of the explosive temperature field. The proposed system and the infrared thermometer were used to measure the temperatures of 375 g, 750 g and 1 500 g explosive charges in experiment. The experimental results show that the maximum deviation of temperature measurement between the system and the infrared thermometer is 3.31%, which realizes the high response rate and high resolution measurement.

Self-adaptive Conjugate Nonlinear Approximation Method for Structural Reliability Analysis

QIU Jiwei, LUO Haisheng

2021, 42(3):  648-654.  doi:10.3969/j.issn.1000-1093.2021.03.022

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When the classical first-order reliability methods are used to solve the reliability problem of nonlinear structure, the accuracy and efficiency of the solution cannot meet the requirements because the calculation process stability is reduced by using the local information of current iterative design point merely. A self-adaptive conjugate aonlinear approximation method is proposed in this work. Firstly, based on the two-point adaptive nonlinear approximation method, a nonlinear approximation model of real limit state function is constructed by using the limit state function value and gradient value of the current and previous iteration design points. Furthermore, on the basis of two-point adaptive nonlinear approximation method, the conjugate search direction is constructed at the current iteration design point by using the limit state function value and gradient value information of the previous two iteration design points. With the development of the iterative process, the nonlinear exponential and the search direction in the model can be adjusted adaptively to improve the approximate accuracy of the model and alleviate the oscillation in the iterative process, then improving the stability of the calculation. Finally, three examples are given to illustrate the applicability of the proposed method.

A Testability Modeling Method Based on Colored Generalized Stochastic Petri Nets

ZHAI Yuyao, SHI Xianjun, HAN Lu, L Jiapeng

2021, 42(3):  655-662.  doi:10.3969/j.issn.1000-1093.2021.03.023

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The relationship between system failures and tests is simplified and the complexity of failure modes is ignored in the existing testability model. A testability modeling method based on colored generalized stochastic Petri nets (CGSPN) is proposed. The complexity of the failure mode is analyzed based on the theory of Petri net, and the severity level is correlated with the color to complete the construction of CGSPN model. The coding scheme is used to distinguish the multiple failure modes of the same failure, thus effectively reducing the difficulty of modeling. A reachability algorithm is used to obtain the correlation matrix. The triangular fuzzy number algorithm is introduced to obtain expert knowledge, and the expert data, as a priori information, and a posteriori test data are used to solve the problem of low data volume and unreliability. Finally, taking a certain type of missile as an example, the CGSPN model was established, and 96.8% fault detection rate and 100% fault isolation rate were obtained. On the basis of meeting testability requirements, the content of the proposed model is enriched.

Continuous Space Pursuit-evasion Game Algorithm Based on Multi-group Deep Q Network

LIU Bingyan， YE Xiongbing， YUE Zhihong， DONG Xianzhou， ZHANG Qiyang

2021, 42(3):  663-672.  doi:10.3969/j.issn.1000-1093.2021.03.024

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A continuous space pursuit-evasion game algorithm based on multi-group deep reinforcement learning is proposed to solve the problems in continuous space pursuit-evasion game(PEG). In order to avoid the insufficient curse of dimensionality of continuous space in traditional reinforcement learning，a TSK fuzzy inference model is established to represent the continuous space.And a pursuit-evasion game algorithm based on multi-group deep reinforcement learning is designed for the complex and time-consuming problems of discrete action self-learning.The simulation environment and motion model were designed by taking the PEG problem of a four-wheel vehicle as an example, and the simulation experiments were carried out with Q-learning algorithm, reinforcement learning algorithm based on qualification trace and genetic algorithm based on reward, respectively. The simulated results show that the continuous space PEG algorithm can be used to solve the problem of continuous space pursuit-evasion game well，and continuously improve the ability to address problems with the increase in learning times，and has the comparative advantages of less time consuming for independent learning and short application time.