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2022, 42(9)

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2022, 42(9): 1-2.

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Numerical Simulation on Traumatic Brain Injury Induced by Blast Waves

ZHANG Wenchao, WANG Shu, LIANG Zengyou, QIN Bin, LU Haitao, CHEN Xinyuan, LU Wenjie

2022, 42(9): 881-890. doi:10.15918/j.tbit1001-0645.2021.191

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Blast-induced traumatic brain injury (bTBI) is a symbol injury in battle physic-cure area, and the injury mechanism is in leading strings. In order to find out the variation law of the space-time pressure field and the dynamic response characteristics of the brain when the blast waves interact with the head, a numerical simulation was carried out to analyze the process of blast wave acting on the head. Firstly, a three-dimensional finite element model with typical human head structure was established, and the validity of the finite element model was verified according to Nahum’s head impact experiments. And then, the simulation was carried out to analyze the impact process of blast waves on human head, concluding the variation law of the space-time pressure field with the interaction of blast waves and the head. Finally, the change of intracranial pressure of head was analyzed. The results show that, after the shock wave impacts on the head, the frontal and parietal lobe of the brain tissue pressure can appear high-frequency pressure cyclical fluctuations, and there will be a higher peak pressure to injure the damageable areas.

Influence of Wedge Angle Disturbance on the Structure of Oblique Detonation

LIU Xi, LI Jian

2022, 42(9): 891-899. doi:10.15918/j.tbit1001-0645.2021.204

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To study the influence of wedge angle disturbance on the structure of oblique detonation, two-step reaction model was used to construct two dimensional reaction Euler equations. The time variable was introduced into the LevelSet function to describe the moving wedge. The influence of wedge angle disturbance on oblique detonation was simulated, and simulation results are that: as the wedge angle increases, the induction length becomes shorter, the structure of oblique detonation changes from abrupt transition to smooth transition, the angle of oblique detonation increases and the oblique detonation moves upstream; as the wedge angle decreases, the induction length becomes longer, the structure of oblique detonation changes from smooth transition to abrupt transition, the angle of oblique detonation decreases and the oblique detonation moves downstream. Complex wave structure evolution will occur in the whole process.

High-Order Pseudo Arc-Length Method for Strongly Discontinuity of Multi-Medium Flows

WANG Chentao, MA Tianbao, LI Kun

2022, 42(9): 900-908. doi:10.15918/j.tbit1001-0645.2021.205

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Considering the strong discontinuities appeared in the solutions of hyperbolic conservation law equations with the development of time and the ability of pseudo arc-length method (PALM) in weakening the singularity of the equation, a high-order PALM was developed based on the combination of the PALM and the high-order weighted essentially non-oscillatory (WENO) scheme to effectively improve the accuracy and resolution of the calculation. To overcome the complexity of a high-order scheme construction in the deformed mesh, a coordinate transformation method was adopted to make the governing equation mapped to the orthogonal uniform arc-length space, completing the calculation in the arc-length space. Combined with Level Set technology and real ghost fluid method (RGFM) interface processing, the algorithm was extended to the calculation of multi-medium flows. For the interpolation of Level Set distance function after grid movement, a third-order non-conservative interpolation scheme was proposed. The results show that the high-order PALM has high convergence order, which can effectively reduce the numerical oscillation at the discontinuity and improve the discontinuity resolution.

Coupling Mechanism Between Damaged Structure and Underwater Explosion Bubble near Free Surface

ZHANG Zhifan, XIE Yujie, WANG Cheng, DENG Wanchao, LIAO Quanmi

2022, 42(9): 909-917. doi:10.15918/j.tbit1001-0645.2022.103

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The dynamic characteristics of underwater explosion bubbles near free surface are very complicated, which is of great significance to studying the mechanism of damaged structure subjected to a second attack by weapon. Based on the coupling Euler-Lagrange (CEL) method, a numerical model of near-free surface underwater explosion was established. The dynamic characteristics of the bubbles in the underwater explosion process of the near-free surface of the (intact) right-angle structure were discussed. The coupling mechanism between the near-free surface underwater explosion bubbles and the damaged structure were revealed. Firstly, the underwater explosion model of near-free surface was established. In order to verify the effectiveness of numerical method, the obtained numerical results such as bubble morphology, maximum radius and period were compared with experimental data. The dynamic characteristics of underwater explosion bubbles near complete and damaged structures were compared. It is found that the joint action of structure and free surfaces causes the bubbles to experience jet deflection, depression on the side of the water mound and bubble fragmentation. The results also show that when the hole size of the damaged structure ranges from 0.070 to 0.085 times of bubble radius, a tilting jet is formed on the side of the structure. The increase of the hole size has a significant positive effect on the head width, head speed and tilt angle of the jet.

A Near-Field Overpressure Estimation Equation of Cylindrical Charge Explosive Air Blast

LIU Jun, WANG Zheng, XIONG Jun, YIN Jianwei

2022, 42(9): 918-927. doi:10.15918/j.tbit1001-0645.2022.113

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After cylindrical charge air blast, an uneven overpressure field is formed in the near-field space. The near-field overpressure at the same equivalent attenuation distance and different angles can differ by several times or even more than one order of magnitude. The use of spherical charge overpressure model in the near field of cylindrical charge air blast will bring great error, so it is necessary to develop a cylindrical charge overpressure model with near-field description ability. Because of the insufficient experimental data, a quick estimation method was proposed to analyze the effect of intensity and distributing of near-field overpressure in cylindrical charges air blast on the area damage and safety. Based on simulated data fitting, an estimation equation of overpressure was developed for cylindrical charge air blast in less equivalent attenuation distance. First, compared with the experience equation of the spherical TNT charge and the experiment results of cylindrical charge, the believable degree of the simulation results was validated respectively for spherical charge and cylindrical charge. Then, based on quadratic polynomial fitting, an estimation equation of near-field overpressure was obtained for cylindrical charge air blast. And the cylindrical charge air blast simulations with different length-diameter ratios were carried out. Finally, the simulation results of the near-field overpressure of cylindrical charge air blast with 6 different length-diameter ratios were compared with their experimental results. The results show that the estimation equation can be used to estimate the overpressure with less error range for cylindrical charge air blast at any position in near-field space. According to preliminary experimental verification, its suitable application range is that the range of cylinder length-diameter ratio is 0.2~2.0 m/kg^1/3.

Fault Diagnosis of Mine Hoist Brake System Based on Improved SAE

LI Juanli, YAN Fangyuan, MIAO Dong, LIU Yimeng

2022, 42(9): 928-934. doi:10.15918/j.tbit1001-0645.2021.210

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In order to reduce the influence of manual subjective intervention on the diagnosis results in traditional fault diagnosis methods, a fault diagnosis method was proposed based on sparse auto-encoder (SAE), using an unsupervised learning method to extract the fault characteristics of hoist monitoring data. First, the failure mechanism of the brake system was analyzed, the monitoring data under the normal operation and failure simulation state of the hoist were collected, and a failure diagnosis datum set was generated. Then a SAE fault diagnosis model was established and optimized based on the Dropout and Adam algorithm. Finally, the performance of the model was tested using a test data set. The experimental results show that the presented method can better avoid the training error of sparse data, reduce the over-fitting phenomenon, and reduce the influence of the local optimum of sparse data. The average classification accuracy of fault types can reach up to 94%, the presented method can realize mine hoist fault diagnosis effectively.

The Nonlinear Finite Element Analysis and Experiment of Mn-Cu Damping Alloy Buffer for Remote Control Weapon Station

ZHU Rui, MAO Baoquan, ZHAO Junyan, GUO Jintao, WANG Zhiqian, CHEN Chunlin

2022, 42(9): 935-946. doi:10.15918/j.tbit1001-0645.2021.216

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There are some problems in the buffer of machine gun remote control weapon station, such as low energy absorption rate, secondary impact and excessive stiffness, which lead to the aggravation of muzzle vibration and affect shooting accuracy. In order to solve the above problems, a new type of buffer was designed and studied based on Mn-Cu damping alloy. The generalized fractional Maxwell constitutive model of Mn-Cu damping alloy was realized in finite element software, and vibration characteristics tests of Mn-Cu damping alloy cantilever beam were carried out to verify the subroutine. Two types of disc spring buffers were designed using genetic optimization algorithm. One is made of 8 pieces of disc springs, which are placed opposite each other. The other is made of 24 pieces of disc springs that set three congruent pieces as one group and the groups are placed opposite each other. After the nonlinear transient finite element analysis for two kinds of new buffer, it is found that the vibration absorption effect of the 24-pieces disc spring buffer is better than the other one. Its vibration acceleration RMS values can be reduced by 66.42% when compared with the original rectangular spring buffer. The static pressure test shows that the static energy absorption rate of 24 pieces disc spring can reach 37.1% at 3 kN. The drop weight test shows that its average dynamic energy absorption is 63.64%, which is 1.51 times that of the original rectangular spring buffer. And its maximum recoil displacement is 2.69 mm, which has decreased 30% compared with that of the original rectangular spring buffer.

Research on 3D Coded Aperture Imaging Based on Coding Metasurface

WANG Ting, YIN Xiangyu, MA Xuhui, ZHANG Runze

2022, 42(9): 947-952. doi:10.15918/j.tbit1001-0645.2021.313

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To solve the problem of low resolution of the radar system for imaging stationary targets in the microwave frequency band, a three-dimentional (3D) imaging system was designed based on metamaterial and coded aperture imaging system, and an optimization algorithm for 3D imaging was proposed. The system divided the space where the 3D target was located into grids on four imaging planes, and constructed the measurement matrix using the irrelevance of the radiation characteristics of the coding metasurface at different encodings, and finally achieved high-resolution imaging of stationary targets in the Ka band. The simulation results show that this imaging system can accurately reconstruct a stationary target within a distance of 2 m; the azimuth resolution is 20 cm, and the distance resolution is 10 cm.

Target Handover Between Midcourse and Terminal Guidance of Ship-Ship Cooperative Guidance for the Ship-Air Missile

ZHAO Yongtao, JIAO Gangling, WANG Junsheng, LI Yafei

2022, 42(9): 953-960. doi:10.15918/j.tbit1001-0645.2021.212

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Aiming at the target handover between the midcourse and terminal guidance in the process of ship-air missile intercepting target over the horizon guided by ship-ship cooperative guidance, a constraint condition was proposed for successful target handover. Firstly, projecting the missile-target line of sight angle vector to a corresponding rotation plane, a calculation model was established for the predetermined pointing angle of the seeker antenna to be suitable for the case of large predetermined pointing angle. And then, an error model was established based on variance analysis method for the predetermined pointing angle of the seeker antenna, and the error sources were analyzed combined with the cooperative guidance operation information flow. Finally, applying probability theory and permutation combination method, a success probability model of single target handover and multiple target handover were established. The simulation results verify the correctness of the predetermined pointing angle calculation error model and the target handover success probability model, as well as its effectiveness in reducing the predetermined pointing angle error and improving the target handover success probability.

Multi-Satellite and Multi-Parameter Observation Based on Reflected Signals from Beidou GEO Satellites for Coastal Wind Speed

WANG Feng, YANG Dongkai, LI Jie, ZHANG Bo

2022, 42(9): 961-968. doi:10.15918/j.tbit1001-0645.2021.217

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In order to explore the retrieval of coastal wind speed, a multi-satellite and multi-parameter observation was proposed based on reflected signals from BeiDou GEO satellites. According to the coherent time of the reflected signal of Global Navigation Satellite System (GNSS) and the area of the normalized delay waveform, the new observation method was carried out based on Principal Component Analysis (PCA) and Linear Unbiased Minimum Variance (LUMV). To demonstrate the retrieval effect of the wind speed with the proposed method, experiments were carried out in Qingdong-5 Tide Well of Dongying city in Shandong province. The experimental results show that compared with the waveform area measure, coherent time measure can express better retrieval performance. Comparing with single-satellite and single-parameter observation, the multi-satellite and multi-parameter observation can provide better result, showing the best precision of 1.15 m/s with LUMV estimator.

Collaborative Deep Reinforcement Learning Method for Multi-Objective Parameter Tuning

LUO Senlin, WEI Jixun, LIU Xiaoshuang, PAN Limin

2022, 42(9): 969-975. doi:10.15918/j.tbit1001-0645.2021.218

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The joint optimization and tuning of multi-objective control parameters is a key issue for the automation system to maintain efficient and stable operation. Reinforcement learning is often used to establish an automated parameter adjustment agent which can replace experts to complete parameter tuning. Existing methods use fixed weights to linearly combine multiple optimization objectives into a single objective and train a single agent model with fixed tuning knowledge, making the actual objective relationship do not match the initialization, the agent can't perceive and make adaptive decision-making adjustments, limiting the effect of parameter tuning. To solve the problem, a collaborative deep reinforcement learning method was proposed for multi-objective parameter tuning. Firstly, an offline simulation was used to learn objective tuning knowledge and to establish multiple Double-DQN agents. Then tuning effect feedback was established online to perceive the actual relationship between the objectives and adjust the agents' coordination strategy to achieve effective multi-objective parameter tuning. The experimental results of automatic train operation parameter tuning show that the proposed method presents better effect on the two goals of parking error and comfort, adapting to different track performance and continue optimization, processing great practical value.

White Balance Consistency Conversion Method for Multi-Camera System Based on Illuminant Estimation

HUANG Hao, LIAO Ningfang, ZHAO Changming, LI Yumei

2022, 42(9): 976-982. doi:10.15918/j.tbit1001-0645.2021.291

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To solve the problem of white balance inconsistency caused by hardware difference of multiple camera modules in multi-camera imaging systems, a white balance consistency conversion method was proposed based on illuminant estimation . The white balance decision point of the source camera was converted to the reference camera by decision point conversion, look-up table and classification decision point conversion method. What’s more, the algorithms were evaluated under various light sources by three indexes: white balance chromaticity ratio difference, white point color difference and full-color color difference. The results show that the proposed look-up table and classification decision point conversion method can effectively improve the white balance consistency of multi-camera modules, meet the requirements of mobile imaging system, and guide the module hardware design and selection of multi-camera imaging systems.

Method of Single Event Effects Radiation Hardened for DC-DC Converter Based on Automatic Detection and Dynamic Compensation

GUO Zhongjie, LIU Nan, LU Hu, LIU Shen, CAO Xitao

2022, 42(9): 983-990. doi:10.15918/j.tbit1001-0645.2022.051

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Taking boost converter as an example, the sensitivity of DC-DC converter to single event transient was analyzed, and the influence of single event transient on loop response was studied. Based on the analysis of the sensitive nodes of the loop, an on-chip automatic detection method at the circuit and system level was proposed to obtain the single particle energy in time, and then transform it into the parameters of dynamic compensation, so as to improve the transient characteristics under different single particle energy. Based on the commercial 0.18 μm BCD process, the circuit design, layout design and physical verification of a highly reliable Boost converter were completed. The experiment results show that, when a system arranged with input voltage 2.9~4.5 V, output voltage 5.9~7.9 V and load ability 55 mA, under the action of single event transient effect, its maximum fluctuation of the output voltage does not exceed 1 mV, the suppression ability can reach more than 86.07%, and can resist LET = 100 MeV·cm²/mg single particle bombardment.

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2022 Vol. 42, No. 9

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