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2019 Vol. 39, No. 12

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2019, 39(12): .
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2019, 39(12): .
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Numerical Simulation of Annular Shaped Charge with Al Liner
WANG Cheng, DENG Tao, XU Wen-long
2019, 39(12): 1211-1218. doi:10.15918/j.tbit1001-0645.2019.071
Abstract(907) PDF(680)
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Based on an annular shaped charge with aluminum liner, different modes of initiation (initiation radiusD1) and length-to-diameter ratio (L/D) were simulated by Autodyn to measure the formation and jet speed of the annular jet. Numerical results showed that the formation process of the annular jet was mainly influenced byL/D, the jet tip had an inward deflection whenL/Dwas relatively small, and an outward deflection otherwise. The axial jet speed was positively related to and also mainly influenced byL/D, and the maximum difference was about 700 m/s. The radial jet speed was mainly influenced by modes of initiation, and the maximum radial jet speed difference was about 220 m/s. The radial jet speed gradient was greater whenD1orL/Dwas relatively small or big. Combined with jet formation and speed,D1=0.5DandL/D=1.0 were preferred settings for this charge. The hole diameter of the concrete target was 2.6D1, which is 7.7% bigger than the numerical result. The penetration experiment demonstrates that the calculation model and method are appropriate.
Experiments of the Interactions Between Double Explosive Bubbles and Free Surface
LI Mei, MA Yu-yu, JIANG Jian-wei, XI Li-ping
2019, 39(12): 1219-1224. doi:10.15918/j.tbit1001-0645.2019.017
Abstract(803) PDF(403)
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In order to study the interaction process between double explosive bubbles and water surface, an underwater explosion experiment in the water tank was conducted. Changes of double explosive bubbles and water curtain were photographed synchronously by two high-speed cameras. The correlation between double explosive bubbles and water curtain was analyzed, and differences between bubble and water curtain with single and double explosive under the same charge and dimensionless depth were compared. The results show that double explosive bubbles undergo the process of single bubble expansion, bubble fusion, fused bubble expansion, fusion bubble shrinkage and collapse. The changes of water curtain take three forms:water mound, water column and water jet. The maximum transverse radius of the fused bubble is 8.7% larger than that of the single bubble, the time of bubble expansion to maximum radius is the same. The water curtain formed by single and double explosive increases exponentially, and the water curtain of double explosive is over 10% higher than that of single explosive after the explosive detonates for 40 ms.
Experimental Research of Steel Box Under Internal Blast Loading
WANG Wei, LIU Guang-kun, WANG Qin, LIU Rui-chao, WU Biao, HUANG Jia-rong
2019, 39(12): 1225-1231. doi:10.15918/j.tbit1001-0645.2019.016
Abstract(1022) PDF(529)
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In order to research the damage effect of steel box under internal blast loading, experiments were carried out to explore the damage of steel box under different TNT charge masses. The common four-compartment steel boxes were used as research objects. By changing TNT charge masses, different damage modes and damage characteristics were observed. The results show that steel box damage level increases as the charge mass increases under the internal blast loading, the steel plate on the roof of the fully enclosed compartment gradually increases from a slight uplift to a crack at the end of the reinforcement, the failure mode gradually increases from slight deformation of inner diaphragm and the steel plate of the roof cover to obvious deformation and the increase of one side uplift of the free passage, and cracks at the reinforced part of the roof and fracture of the top of inner diaphragm are formed at last.
Experimental Research on Fracture of Concrete with Prefabricated Holes
WANG Yi-xian, WANG Zhi-qiang, ZHANG Wei, LIU Fei-fei
2019, 39(12): 1232-1238. doi:10.15918/j.tbit1001-0645.2019.019
Abstract(706) PDF(391)
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In order to investigate the process of crack initiation, propagation, evolution and penetration under loading conditions, concrete specimens with different numbers of prefabricated holes were created and fracture experiments with uniaxial loading were conducted. Numerical simulation was done using the ANSYS software to analyze stress distribution according to the experimental process. Experimental results and numerical calculations were compared. Experimental results showed that the failure mode of the specimen and the penetration mode of hole are related to the number and distribution of holes. The failure modes of the specimen are mainly splitting failure and shearing failure. The results obtained with the ANSYS software are consistent with the experimental results.
Test Study and Simulation Analysis on Bearing Performance of CFRP Base Plate
YIN De-jun, ZHENG Jian, XIONG Chao, YIN Jun-hui, LI Bao-chen, XI Tao
2019, 39(12): 1239-1245. doi:10.15918/j.tbit1001-0645.2019.236
Abstract(813) PDF(443)
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The bearing performance of carbon fibre reinforced plastics (CFRP) base plate was studied by live firing tests. The coupled finite element model of CFRP base plate and soil was established by ABAQUS. The influence of the powder charge quantity and firing angle on the mechanical responses of CFRP base plate was analyzed. The simulation results were in good agreement with the test results, which verified the rationality of the finite element model. Comprehensive analysis showed that the strength and stiffness of CFRP base plate basically could meet the requirements of application. When the firing angle is the same, the maximum stress and displacement of CFRP base plate increase with the increase of the powder charge quantity. When the powder charge quantity is the same, the maximum stress and displacement of CFRP base plate decrease with the increase of the firing angle.
Flow Field Characteristics of Pressure Independent Constant Airflow Control Valve
MENG De-yuan, CHEN Fei, ZHANG Hai-yun, PENG Xi, LI Qing-yang
2019, 39(12): 1246-1251. doi:10.15918/j.tbit1001-0645.2018.442
Abstract(854) PDF(496)
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In order to meet the need of accurate airflow control in hospital operating room, biochemical laboratory and clean room, an airflow control valve with a mechanical, pressure-independent regulator was developed. Adjusting the flow area of the regulator automatically, the valve was designed to be able keep the air flow in a pre-established value, being unacted on duct pressure varies. Based on the CFD technology, the flow field of the airflow control valve was modeled and simulated to analyze the influence of the key structural parameters on the flow field characteristics and carry out optimized design of the valve. And a testing device was built for the airflow control valve to verify the performance of the pressure independent valve.
Design and Performance Study of Magnetorheological Fluid Damper for Pipeline Vibration Control
XIN De-kui, NIE Song-lin, JI Hui, NI Qi
2019, 39(12): 1252-1257. doi:10.15918/j.tbit1001-0645.2018.448
Abstract(777) PDF(412)
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To meet the requirements of vibration and noise reduction in hydraulic pipeline, a design method of double-outlet shear-valve magnetorheological(MR) damper was proposed. Based on the Bingham model of MR damper, combining the structural design of the MR damper with the design of the magnetic circuit, the calculation formula of the structural parameters of the damper was deduced. A finite element analysis software COMSOL was selected to simulate the electromagnetic field. An accurate and simple computational method based on the simulation model was established to calculate the viscous stress and shear stress under different control current. According to the proposed design method, a prototype of MR damper was developed, and the dynamic mechanical properties of prototype were tested. The test results show that the performance parameters of the MR damper are basically identical with the theoretical design values, which proves the correctness and feasibility of this design method, and the design method can simplify the design process and reduce the volume of MR damper.
Research on Network Intrusion Detection Based on SMOTE Algorithm and Machine Learning
ZHANG Yang, ZHANG Tao, CHEN Jin, WANG Yu, ZOU Qi
2019, 39(12): 1258-1262. doi:10.15918/j.tbit1001-0645.2018.423
Abstract(901) PDF(668)
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The machine learning model has been widely used in network intrusion detection, but researchers pay more attention to model selection and parameter optimization, but rarely consider the impact of data imbalance, which often leads to poor detection effect of a small number of intrusion samples. To solve this problem, focusing on the data rebalancing algorithm of SMOTE(synthetic minority oversampling technique), taking the intrusion detection data set KDD99 as the original training set,a simple sampling method and SMOTE algorithm were used to generate the rebalancing training set. And then,a variety of machine learning models were used to perform 5 fold cross-validation for the original training set and the rebalanced training set respectively. Experimental results show that, compared with the original training set, the use of rebalancing training set modeling can improve the recognition accuracy and recall rate of the minor class samples by about 10%~20% without reducing or even improving the recognition effect of major class samples. Therefore, SMOTE algorithm can significantly improve network intrusion detection under unbalanced samples.
A Robust Beamforming Algorithm for Arbitrary Array
CAO Yuan, LIU Wei, CUI Dong-hua
2019, 39(12): 1263-1267,1297. doi:10.15918/j.tbit1001-0645.2019.144
Abstract(873) PDF(452)
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Aiming at the steering vector mismatch caused by the angle error of the desired signal and the rapid change of the interference, a novel null broadening robust adaptive beamforming algorithm was proposed in this paper. Firstly, a covariance matrix was reconstructed for the received signal, and then the flattened main lobe beam was constrained according to the approximate desired signal angle. Finally, an iterative algorithm was proposed to solve the non-convex optimization problem after the above processing steps. The simulation results show that the proposed algorithm has better robustness than the traditional algorithm to the mismatch of signal angle and the rapid change of interference. Being applicable to arbitrary arrays, the algorithm possesses great practical significance in engineering.
Study on Air-Ground Probability Data Association Converted Measurement Filter Algorithm
LUO Yu-wen, LIU Dan, FAN Xiong-hua, JIANG Jing
2019, 39(12): 1268-1276. doi:10.15918/j.tbit1001-0645.2018.231
Abstract(684) PDF(394)
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To solve the problems of false alarms, large elevation error and losing detections in airborne early warning radar, a new tracking method was proposed based on air-ground PDA-UCMKF in WGS-84 coordinate system for airborne early warning radar to improve the track initiation and target tracking. A state and covariance update formula was deduced in WGS-84 for airborne early warning radar to achieve target tracking quickly in high altitude. Compared with NN-UCMKF method, the association and tracking effects of PDA-UCMKF were simulated in mixed wave condition. The results show the efficiency and reliability of PDA-UCMKF method, and easy to implement in engineering.
A TV Signal Power Detection Method Based on UAV Platform
DONG Si-qiao, SHI Qing-lin, LIU Xuan, ZHU Lin
2019, 39(12): 1277-1284. doi:10.15918/j.tbit1001-0645.2018.305
Abstract(932) PDF(433)
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In this paper, a novel method of television signal power radiation detection was presented to detect the equivalent isotropically radiated power (EIRP) of TV transmitting end. On the hardware, a TV signal power low altitude radiation detection system was designed based on UAV to measure the frequency and power of TV signal. On the software, a power path loss compensation algorithm of TV signal was developed to filter, calculate, store and display the data. Compared with the traditional method, the TV signal power of the new system in Zhengzhou and Shijiazhuang was tested and validated. Results show that, the measure error of the proposed method is 5 dB less than that of the traditional ground radiation detection system. The new method can effectively solve the problem of ground detection and location, reduce the detection error caused by complex environment and equipment defects, and improve the detection efficiency and accuracy.
Face Image Colorization Based on Generative Adversarial Networks
HAN Xian-jun, LIU Yan-li, YANG Hong-yu
2019, 39(12): 1285-1291. doi:10.15918/j.tbit1001-0645.2018.432
Abstract(989) PDF(498)
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In this paper, a novel face image colorization method was proposed based on a generative adversarial network. Two groups of generative adversarial sub-networks were involved in the network structure, a generator and a discriminator. One of the sub-networksA(containing generatorAand discriminatorA) could implement the translation process from gray-scale images to color images, while another sub-networkB(containing generatorBand discriminatorB) could reverse the process. Taking the generated image of sub-networksAas input, the sub-networksBcould reconstruct the original gray face image. The whole structure was arranged to ensure the invariance of human face identity, the loop loss in the network was for image reconstruction, the generative loss and adversarial loss were used to make the generated image close to the real image. The experimental results show that this structure can not only achieve a natural and realistic face image, but also ensure that the identity of the face.
Separate Meter in and Meter out Valve Controlled Cylinder System Based on Dual Servo Control
NIU Shan-shuai, WANG Jun-zheng, ZHANG Peng, WANG Shou-kun
2019, 39(12): 1292-1297. doi:10.15918/j.tbit1001-0645.2018.456
Abstract(982) PDF(522)
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Aiming at the need for control precision and energy saving of electro-hydraulic servo system, a kind of separate meter in and meter out valve controlled cylinder system was proposed based on dual servo control. First, a mathematical model of the system was established. Then, the system was completely decoupled by using the adaptive robust method. According to the position servo conditions with active or negative loads, the inlet controller for position tracking and the outlet controller for pressure control were designed. At the same time, the energy saving of the system was analyzed, a source pressure controller was designed based on the ESO and the hydraulic pump flow servo controller was designed. Finally, the experiments were carried out to verify the control performance and energy-saving effect of the system.
A Motion Reconstruction Technology for Distributed Collaborative Plotting of AR Sand Table
LI Wei-hao, YAO Shi-ming, LI Wei-qing, SU Zhi-yong
2019, 39(12): 1298-1303,1320. doi:10.15918/j.tbit1001-0645.2018.431
Abstract(752) PDF(416)
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In order to realistically reproduce the interactive process of collaborative plotting of holographic electronic sand table under the augmented reality environment, a video-based distributed collaborative plotting reconstruction method was proposed. Firstly, the operators were tracked based on YOLO using a single RGB camera simultaneously to estimate the relative position of those people in 3D space. And an improved ResNet network was used to predict 3D joint positions for every operator. Then the estimated joint positions of the local operators were sent to other place to drive the avatar's movement in real time through low-pass filter and the method of inverse kinematics. The experiment results show that the proposed method can reproduce the operator's motion and meet the application requirements.
Study on In-vivo Electrical Properties Tomography for Human Tissue by High Field Magnetic Resonance
LI Xiao-nan, LIU Guo-qiang, LI Xiao-kai, HU Li-li, YUAN Zi-long, ZHU Jing
2019, 39(12): 1304-1310. doi:10.15918/j.tbit1001-0645.2019.223
Abstract(899) PDF(376)
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Early screening and diagnosis of diseases, such as malignant tumor and stroke, have always been the focus in the field of clinical medicine. Combined with modern imaging methods, a magnetic-resonance-imaging (MRI) based electrical characterization method for biological tissues was proposed. According to the fact that MRI scanning signal having the information of the electrical conductivity and dielectric constant in target body, the interaction between radio frequency magnetic field and electrical properties under the Faraday's and Ampere's laws was derived. Taking the volunteer's head as the condition of the imaging experiment, a high field MRI scanner experiment was carried out based on a double-angle method with spin echo sequence to obtain the preliminary images for the radio frequency magnetic fields and the electrical properties.Results show that, when the gradient terms were involved in the improved algorithm, the electrical characterization of different tissues shown in the image was more evidence. Compared with the traditional electrical impedance tomography and conventional MRI, the new magnetic resonance electrical properties tomography presents higher contrast and higher resolution.As a kind of functional imaging, it is hopeful to be used in the prevention and diagnosis of relevant major diseases.
Meso Numerical Simulation of Composite Explosives Under High Strain Rate
GUO Hong-fu, WU Yan-qing, LI Ji-dong, QU Ke-peng, XIAO Wei, CHEN Peng
2019, 39(12): 1311-1314. doi:10.15918/j.tbit1001-0645.2019.022
Abstract(802) PDF(436)
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A meso-numerical model was established to study the effects of RDX crystals and binders on the average mechanical properties of composite explosive 8701. The dynamic stress-strain curve of 8701 at strain rate 600/s was obtained by SHPB test.The macroscopic stress-strain curve was calculated according to the Tayler homogenization method.The results showed that the meso-numerical calculation model well describes the mechanical properties of 8701. Under high strain rate loading, the stress of RDX grain and binder increases with strain, but the strength and content of RDX are greater, so the mechanical properties of RDX grain play a leading role in the mechanical properties of 8701.
Marketing System Analysis Based on Structural Equation and Multiple Regression
WU Xu, WU Qing-sheng
2019, 39(12): 1315-1320. doi:10.15918/j.tbit1001-0645.2018.481
Abstract(777) PDF(409)
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In order to study the role of content marketing information dissemination in the process of brand equity's creating value in the industrial market,the content marketing information was effectively deconstructed:based on functional and emotional information in the B2C market-driven marketing strategy, the existence of unique pioneering information in B2B market-driven marketing strategy was discovered. Moreover, brand equity was regarded as a key factor in the impact of B2B content marketing information dissemination on brand performance and finally a marketing system of "B2B content marketing information dissemination-brand equity-brand performance" was constructed. The research empirically analyzed data from 325 suppliers and concluded that three types of information dissemination have positive impact on the establishment of strong brand equity, brand equity has positive impact on brand financial performance, and three types of information dissemination have positive impact on brand financial performance, while public information channels significantly strengthen the positive effect of emotional and pioneering information on brand financial performance.
2019, 39(12): 1321-1338.
Abstract(730) PDF(481)
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