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Aerodynamic Characteristics of a Missile Model with Direct Force and Aerodynamic Force Compound Control Technology ZHAO Zhongliang, LI Hao, LAI Jiang, YANG Haiyong, WANG Xiaobing, LI Yuping Air & Space Defense    2022, 5 (3): 1-9.   Abstract （248）      PDF（pc） （4676KB）（739）       Knowledge map    Save The direct force and aerodynamic force compound control technology is proposed for achieving the rapid turning and precise guided strike in high-maneuver tactical missiles. To investigate the coupling interaction problems in the compound control method, both wind tunnel experiments and unsteady numerical simulations are conducted on a typical missile configuration with transverse jet nozzles. Specially, dynamic response to the direct force/aerodynamic force control are carried out experimentally in wind tunnel. The results shows that the rear transverse jets provide beneficial interaction for aerodynamic characteristics. As a consequence of the pitching motion, the upstream separation region is largely affected by the unsteady interaction flow. And the aerodynamic coefficients experience obvious dynamic hysteresis, which is enhanced by the pitching motion rate. The amplification factor of pitch moment is more seriously affected under large angle-of-attack in the pitching motion, which is deviated from the static counterparts and leads to unfavorable impact. The direct force/aerodynamic force compound control is proven to be capable of increasing the pitching-up velocity, and it is a reliable option for rapid turning and precise attitude control. Related Articles | Metrics | Comments（0）

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Research Progress of Optical Aperture with Supersonic Film Cooling Under Hypersonic Flight Environment YI Shihe, DING Haolin Air & Space Defense    2021, 4 (4): 1-13.   Abstract （1070）      PDF（pc） （8474KB）（1081）       Knowledge map    Save Under hypersonic conditions, the existence of aero-optical effects seriously affects the accuracy of infrared imaging guidance, which has become one of the key technical problems in the development of a new generation of hypersonic precision strike weapons. It is necessary to study the optical aperture with supersonic film cooling suitable for hypersonic flight environment so as to solve the thermal protection and imaging problems of optical aperture under hypersonic flight conditions and break through the speed and temperature limitations of existing infrared imaging guidance weapons. Finally, it provides support for the realization of weapons' high-precision strike against air, ground, and sea under hypersonic conditions. Related Articles | Metrics | Comments（0）

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Infrared Dim and Small Target Detection Based on Dual-Channel Feature-Enhancement Integrated Attention Network CAI Yunze, ZHANG Yanjun Air & Space Defense    2021, 4 (4): 14-22.   Abstract （422）      PDF（pc） （2312KB）（627）       Knowledge map    Save Aiming at the problems existing in long-distance infrared target detection, such as less feature information, complex environment, more noise interference, and high missed detection rate and false alarm rate of traditional target detection algorithms, an infrared small target detection algorithm based on dual-channel feature enhancement attention network is proposed in this paper. The overall network structure mainly includes three parts: dual channel feature extraction module, feature enhancement module and integrated top-bottom attention module. Compared with single channel feature extraction, dual channel feature extraction can obtain more feature information. Feature enhancement module can enrich target features further. Moreover, the integrated top bottom attention module can adaptively enhance target features and weaken background noise. And then the algorithm improves the detection effect of dim and small targets in the infrared images. Finally, it is verified that the algorithm proposed in this paper has a better detection effect, and has a lower rate of missed detection and false detection. Related Articles | Metrics | Comments（0）

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Neural Network Based Air Defense Weapon Target Intelligent Assignment Method LONG Teng, LIU Zhenyu, SHI Renhe, WANG Shengyin Air & Space Defense    2021, 4 (1): 1-7.   Abstract （604）      PDF（pc） （1317KB）（538）       Knowledge map    Save To address the challenge of the real-time weapon target intelligent assignment in modern high dynamic air defense operation, a neural network based air defense weapon target intelligent assignment method is proposed in this paper. An optimization model for weapon target assignment is first established considering the number of weapons and interception capability in order to optimize the damage efficiency. A neural network based weapon target intelligent assignment framework is then developed, where a neural network is constructed based on the existed training sample set and employed to assign the weapons to the targets effectively and efficiently. The comparison results illustrate that the neural network based air defense weapon target assignment method can obtain better weapon target assignment solution compared with the conventional discrete differential evolution based assignment method. Moreover, the computational cost of the proposed method can be reduced by 99. 9%, which demonstrates the effectiveness and practicability of the research work. Related Articles | Metrics | Comments（0）

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Adversarial Attack Technology for Vision-Based Aircraft Intelligent Object Detection JIANG Xinghao, ZHAO Zheyu, XU Ke Air & Space Defense    2021, 4 (1): 8-13.   Abstract （498）      PDF（pc） （5500KB）（617）       Knowledge map    Save With the rapid development of artificial intelligence and computer vision, using intelligent object detection technology to identify the aircraft and UAV has become a common military defense means. Aiming at the feasibility of confusing and deceiving the object detection model based on deep learning network from the digital image level, and materializing the digital attack results in the future, this paper proposes a limited area adversarial attack method for vision-based aircraft intelligent object detection. The digital image of aircraft is used to simulate the adversarial attack of YOLO v3 object detection network. The effectiveness of the proposed method is verified by the experiments on the aircraft categories in PASCAL_VOC_2007 dataset.  The work of this paper provides the basis for further research on whether the digital analog attack can be transferred to the aircraft entity. Related Articles | Metrics | Comments（0）

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Research on Time Delay Control Techniques for High Time Accuracy Infrared Scene Generation DU Huijie, DU Jian, ZHANG Xing, REN Zhong Air & Space Defense    2020, 3 (4): 8-13.   Abstract （243）      PDF（pc） （6030KB）（145）       Knowledge map    Save Focusing on the time delay requirement for infrared dynamic scene generation of the high time accuracy hardware-in-the-loop simulation, two kinds of low-stability time delay control techniques were introduced: the internal storage mapping technique based on PCI-E bus and the scene generation system based on Many-core processor system. The result will provide support for establishing the timing controllable low-stability time delay infrared dynamic scene generation system. Related Articles | Metrics | Comments（0）

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Terminal Angle Constraint Sliding Mode Guidance Law Design Based on Fixed-time Convergence ZHANG Xiaoyu, ZHANG Peng, ZHENG Xin, NI Yuanhua Air & Space Defense    2020, 3 (3): 9-15.   Abstract （448）      PDF（pc） （6111KB）（140）       Knowledge map    Save In order to improve the target destruction by the missile and achieve successful interception of the target in a bounded finite time, a terminal angle constraint sliding mode guidance law based on fixed-time convergence is proposed. Firstly, a plane guidance system model of missile intercepting target is established, and the target maneuver is regarded as unknown bounded disturbance. Secondly, a fixed time disturbance observer is used to observe the disturbance of the guidance system. Thirdly, the terminal angle constraint guidance law is designed based on fixedtime convergence sliding mode control and fixed-time disturbance observers. The fixed-time stability of the guidance system is proved, and the convergence domains of guidance system states are given. Finally, it is verified that the designed guidance law can achieve intercepting the target at a specified angle while ensuring accurate interception via numerical simulations. Related Articles | Metrics | Comments（0）