基于结构相似度的SAR干扰效果评估方法

传统的合成孔径雷达(SAR)图像质量评价指标没有考虑像素点间的相关性和人眼视觉系统感知特性,导致主客观不一致的现象时有发生。提出了一种主客观相结合评估方法,该方法不仅巧妙地利用了结构相似度(SSIM)作为主客观评价的连接纽带,而且结合局部方差相似度与图像高频信息相对应的特点,通过非线性合并得到了结构相似度的修正模型。仿真结果表明,该方法较之传统评估手段具有明显的优势,不仅能够更好地反映出干扰对图像细节的影响,而且能够与人类视觉系统保持高度一致,进一步提升了整套评估系统的效率和准确率。     

通信干扰试验干扰效果的评估与分析

分析了通信干扰设备靶场试验的目的、对象及方法,并对干扰效果的评估及有效性进行了详尽的阐述和分析。     

小口径炮激光模拟器光束传输特性的研究

本文采用多横模振荡模型,对小口径炮激光模拟器光束传输特性进行了分析,导出了射程及光斑大小与激光功率、探测器阈值辐照度、光学系统及大气衰减的关系。并根据现有条件用计算机进行了计算,给出了激光传输过程中光斑分布的理论曲线。在此基础上进行了实地测量,实验值与理论曲线基本吻合。本文对激光模拟器的研制和应用具有一定的参考价值。     

激光模拟器的模匹配

本文根据椭圆高斯模的传输和变换理论,分析了椭圆高斯模的模式变换,讨论了模式匹配的计算,并列举了两种椭圆高斯模的计算实例。     

多波段隐身兼容中的几个矛盾问题的分析

多波段隐身兼容是隐身技术发展的方向,但是每增加一个隐身内容或波段,都对隐身兼容的实现增加很大的难度。分析了多波段隐身兼容技术中存在的几个矛盾问题,包括1 06μm激光隐身与近红外隐身兼容的矛盾、主被动毫米波隐身兼容的矛盾、10 6μm激光与8～14μm热红外隐身兼容的矛盾,同时探讨了解决这些矛盾问题的方法。     

Hyperspectral imaging and remote trace detection of cis-1,3,4,6-tetranitrooctahydroimidazo-[4,5 d] imidazole (BCHMX) compared with traditional explosives using laser induced fluorescence

cis-1,3,4,6-Tetranitrooctahydroimidazo-[4,5 d] imidazole (BCHMX) is an advanced energetic compound that expected to spread worldwide in the near future. Since, no approved remote detection methods were reported in current literature for this material, we performed hyper-spectral imaging and laser induced fluorescence (LIF) to a BCHMX sample under low laser fluence for determining the optimum laser wavelength used in any future BCHMX-LIF based remote detection systems. For this purpose, an experimental setup consisted of a sun spectrum lamp and hyper-spectral camera was built to illuminate and image white powder samples of BCHMX in comparison with the traditional explosives, HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane), RDX (1,3,5-trinitro-1,3,5-triazacyclohexane), PETN (2,2-Bis[(nitroxy)methyl]propane-1,3-diyldinitrate). The imaging reveals strong BCHMX sample absorption contrast among other samples at wavelength ranging from 400 to 410 nm. When light source was replaced by a 405 nm laser diode illuminator, a strong BCHMX sample LIF at the spectral range from 425 to 700 nm was observed under low laser fluence condition of 0.1 mJ/cm². Finally, we demonstrated successfully the ability of the 405 nm LIF and the hyperspectral imaging technique to detect finger print traces of BCHMX on white cellulose fabric from a distance of 15 m and a detection limit of 1 μg/cm².     

Impact of atmospheric turbulence on coherent beam combining for laser weapon systems

The performance of a laser weapon system based on coherent beam combining (CBC) depends on its propagation properties in the atmosphere. In this study, an analytical model based on partial coherent beam combining (PCBC) for assumed coherence coefficients between beams in a CBC lattice was developed. The Kolmogorov model of atmospheric turbulence and the Hufnagel-Valley model of Cn2 dependence on atmospheric parameters were implemented. Novel simplified metrics were proposed to assess the CBC performance. Several beam profiles (super-Gaussian, truncated Gaussian, etc.) and ge-ometries were analyzed in terms of maximal intensity in the far field. An approximate formula for PCBC efficiency dependent on the Fried radius was proposed. The results of CBC modeling were compared to those of the Gaussian beam propagation model in a turbulent atmosphere. The dependence of CBC performance on the Cn2 parameter, range, and elevation angle was analyzed. It could be concluded that the application of CBC for medium and long range propagation is impractical without an effective adaptive optics system.     

Damage to aircraft composite structures caused by directed energy system: A literature review

This paper presents a comprehensive review of the research studies on direct energy system effect on aircraft composite structures to develop a good understanding of state-of-the-art research and devel-opment in this area. The review begins with the application of composite materials in the aircraft structures and highlights their particular areas of application and limitations. An overview of directed energy system is given. Some of the commonly used systems in this category are discussed and the working principles of laser energy systems are described. The experimental and numerical studies re-ported regarding the aircraft composite structures subject to the effect of directed energy systems, especially the laser systems are reviewed in detail. In particularly, the general effects of laser systems and the relevant damage mechanisms against the composite structures are reported. The review draws attention to the recent research and findings in this field and is expected to guide engineers/researchers in future theoretical, numerical, and experimental studies.     

机载无源干扰诱饵的运动特性研究

考虑机载无源干扰诱饵自身的属性和其所处的大气环境,对其进行受力分析,发现无源干扰诱饵受空气动力和自身重力的影响较大。据此建立了无源干扰诱饵的动力学模型和运动学模型,仿真得出无源干扰诱饵的运动情况。在对箔条云受力和单根箔条受力分析的基础上,给出等效球的概念,在仿真中直观地得到了箔条云的散开过程。     

一种产生雷达多假目标的卷积调制法

讨论了多假目标干扰技术特点及应用背景,分析了用卷积调制法产生多假目标的原理,讨论了卷积器的设计方法,确定了卷积器的加权系数。仿真分析表明,卷积调制法产生多假目标方法灵活,可以实现脉内和脉间密集多假目标干扰技术,验证了方法的合理性。