尖头弹侵彻延性金属靶板弹道极限的解析模型

现有的尖头弹侵彻金属靶板的弹道极限计算模型往往需要大量的试验数据和靶板材料的动态性能参数,且没有考虑侵彻速度对侵彻效果的影响,这给工程应用带来了很大的不便和误差。基于这一问题,考虑速度效应和靶板材料参数对侵彻的影响,结合流体动力学原理与动态空穴膨胀理论,分别提出了双模式和单模式侵彻模型。双模式侵彻模型的侵彻过程可分为两个阶段：流体动力变形阶段和塑性变形阶段,当侵彻速度小于靶材产生流体动力变形的临界速度时,侵彻进入塑性变形阶段,根据功能原理,建立了计算弹道极限的解析模型;单模式侵彻模型仅考虑塑性变形阶段。解析模型计算的弹道极限与弹道试验结果吻合的较好,且模型中不涉及弹道试验数据和靶板材料的动态性能参数,易于迅速求解,便于工程应用,可用于对延性金属靶板抗尖头弹侵彻能力的评估。     

基于深度学习的合作目标靶球检测

为了解决复杂场景下激光跟踪仪对合作目标靶球的精确识别难题,提出了基于深度学习的合作目标靶球高效检测方法。首先分析了合作目标靶球的图像特征,然后采用改进的YOLOv2模型,针对合作目标靶球多尺度与小目标占比多的特点,提出了一种基于注意力机制的改进方法,同时为提高网络模型对复杂背景的抗干扰能力,提出了一种数据增强方法。测试结果表明,所提出的基于注意力机制与数据增强的改进YOLOv2模型对复杂背景的抗干扰能力较强,且对合作目标靶球的检测精度有显著提高,在合作目标靶球测试集上的检测准确率达到92.25%,能够有效满足激光跟踪仪在大型装置精密装配过程中的目标检测精度需求。     

红外与雷达隐身涂层激光后向散射特性

研究了红外与雷达波隐身涂层的激光后向散射特性。研究结果表明:涂层的红外辐射率越小,激光后向反射率越大。从目标战术应用上考虑,通过对目标进行合理的迷彩图案设计,有可能实现红外与激光隐身兼容;从隐身原理和材料设计来考虑,完全可以做到雷达与激光隐身兼容;通过涂层表面结构微孔化,可使涂层激光后向反射率大大下降,而不影响雷达波隐身性能。      

脉冲激光蒸发熔融织构靶制备的YBa2Cu3O7-δ超导薄膜

用脉冲激光蒸发熔融织构靶材在SrTiO3(001)单晶基片上制备了YBa2Cu3O7-δ超导薄膜。用X射线衍射仪、透射电镜和原子力显微镜分别对薄膜的微观结构和表面形貌进行了分析。结果表明，薄膜呈c轴取向，薄膜中有一定数量的颗粒状Y2O3杂相，且具有择优取向，而靶材中所含的Y2BaCuO8相却没有在薄膜中形成。沉积温度升高，有利于[001]取向，但不利于[111]取向的Y2O3形成。与传统的粉末烧结靶相比，用熔融织构靶制备YBa2Cu3O7-δ薄膜可以明显抑制薄膜表面颗粒的形成。     

弹丸初速激光测定系统研究

本文对多普勒雷达测速、天幕靶测速和激光测速的原理进行了对比分析,详述了以89C52单片机为核心的新型激光初速测定仪原理、电路设计和火炮初速推算方法.同时,围绕影响测试精度的因素进行了分析探讨,确定了测定各种火炮初速所需的靶距和第一靶距炮口的最小距离.     

大面积平行光幕弹着点测试系统

研究了基于平行激光幕大面积弹着点坐标测试方法.以半导体激光线发生器为光源,用长焦距消球差的柱面菲涅耳透镜形成平行激光幕单元,通过多个平行激光幕单元的无缝拼接可形成大面积靶面.由于平行激光幕单元内沿宽度方向通量密度呈高斯分布,一定直径的弹丸通过光幕的不同横向位置时探测器获取信号不同,因此可根据信号的幅值来细分平行激光幕单元宽度范围内弹着点的位置.通过口径为7.62mm的实弹射击试验验证了细分方法的可行性.结果表明了该系统有足够的灵敏度能获取小目标的过靶信号;在10 m长靶面的试验系统中测量坐标值与弹孔测量坐标值差值的标准差为5.16 mm.     

二项专利将催生新一代吊车

其一,于吊车吊钩动滑轮组护板外侧装设基准激光与吊钩偏角激光发生器,当吊钩偏角0°时,吊钩偏角激光光束,和始终铅垂方位的基准激光光束中心线重合,当吊钩产生偏角时,吊钩偏角激光光束偏离基准激光光束,显示出吊钩偏角的方向和偏角大小,并依其操纵实现垂直吊装;其二,抬吊要求在协同吊装下进行,吊车间互为协同方,鉴于抬吊风险来自吊车载荷超常变动和不垂直吊装,故将吊车载荷动态与吊钩偏角动态,传输、显示于协同方吊车操作室,令双方在"知已知彼"条件下实现协同吊装回避抬吊风险;因而可依二项设想[1-2]开发激光显示、监视垂直吊装,且回避不垂直抬吊与载荷超常变动风险的新一代吊车。     

增设吊车吊钩偏角激光监视设置的作用

其一,于吊车吊钩动滑轮组护板外侧装设基准激光与吊钩偏角激光发生器,当吊钩偏角0°时,吊钩偏角激光光束,和始终铅垂方位的基准激光光束中心线重合,当吊钩产生偏角时,吊钩偏角激光光束偏离基准激光光束,显示出吊钩偏角的方向和偏角大小,并依其操纵实现垂直吊装;其二,抬吊要求在协同吊装下进行,吊车间互为协同方,鉴于抬吊风险来自吊车载荷超常变动和不垂直吊装,故将吊车载荷动态与吊钩偏角动态,传输、显示于协同方吊车操作室,令双方在"知已知彼"条件下实现协同吊装回避抬吊风险;因而可依二项设想[1-2]开发激光显示、监视垂直吊装,且回避不垂直抬吊与载荷超常变动风险的新一代吊车。     

激光辐照参数对光导型光电探测器响应的影响

文章针对激光照射下光导型碲镉汞光电探测器的响应特性展开了研究,主要讨论了强激光照射下辐照时间、波长及光功率密度对探测器响应特性的影响.从传统载流子的漂移扩散模型出发,在考虑温度的变化下推导出描述半导体载流子的动态方程,并通过数值模拟,给出了理论上的激光辐照主要参数对探测器电阻及输出电压的影响.结果表明:半导体探测器材料...     

加筋板架和均质靶板抗截卵形动能弹穿甲数值模拟研究

舰舷结构在高速冲击载荷作用下的穿甲是非常复杂的高度非线性动态响应过程,介绍了穿甲过程中的基本理论和MSC/DYTRAN的数值解法,以舰舷结构为目标,对截卵形弹头贯穿均质靶板和加筋靶板的实验过程中的几个典型工况进行了数值模拟研究,研究结果表明,数值方法模拟穿甲过程是可行的。另外,还研究不同屈服应力和硬化模量的靶板材料、板厚和弹体初速度对弹体剩余速度和靶板能量吸收的影响。     

激光通信中雨滴、烟雾信道相干带宽特性研究

本文选用合理的模型模拟了大气信道中雨滴、烟雾带来的相干带宽,并进行了数值计算。结果表明:对于雨滴、轻雾信道,相干带宽很宽;而对于烟雾浓度较大的信道,信道的相干带宽应引起激光大气通信的重视。     

Simulation of error in optical radar range measurements

We describe a computer simulation of atmospheric and target effects on the accuracy of range measurements using pulsed laser radars with p-i-n or avalanche photodiodes for direct detection. The computer simulation produces simulated images as a function of a wide variety of atmospheric, target, and sensor parameters for laser radars with range accuracies smaller than the pulse width. The simulation allows arbitrary target geometries and simulates speckle, turbulence, and near-field and far-field effects. We compare simulation results with actual range error data collected in field tests.     

脉冲激光模拟器

介绍了一种用于测试激光测距机系统性能的脉冲激光模拟器。该模拟器由１０６４ｎｍ半导体浙江器、准直光学系统、驱动电路、同步及延迟电路、仿真计算软件等组成,可以模拟脉冲激光测距机在各种大气条件下,对不同距离及不同特性的目标测距时的回波信号。     

高精度激光准直技术的研究（一）

论述了激光准直技术的发展及共性的技术关键问题，系统介绍了对单位在高精度激光准直技术方面的研究成果，从理论到实践较好地克服激光漂移，大气环境对激光准直的严重影响。研制成功的激光光纤准直仪，激光双频同轴度仪及激光旋光准直仪具有当前高精度激光准直技术的代表性，并且均达到国内外先进水平。     

Numerical modelling of laser beam-target interaction near the plasma-formation threshold

Experimental investigations of laser-produced plasmas often determine plasma parameters as averaged values only and these data cannot be compared with actual conditions at a target surface. In this paper, numerical modelling of target heating with non-constant target material properties was used to estimate the temperature at the surface of the target as a function of time. Three target materials (magnesium, aluminum and silicon) and an experimentally determined laser pulse profile were used for modelling. Gray-body radiation of the target surface and thermal diffusion losses are taken into account during numerical modelling. It was assumed that radiation from the laser impacts perpendicularly onto the target surface. The results obtained by modelling are in good agreement with the experimentally observed plasma parameters and they are consistent with thermal target heating in which the laser beam is treated as a source of very intense input heat energy.     

Atmospheric electromagnetic pulse propagation effects from thick targets in a terawatt laser target chamber

Generation and effects of atmospherically propagated electromagnetic pulses (EMPs) initiated by photoelectrons ejected by the high density and temperature target surface plasmas from multiterawatt laser pulses are analyzed. These laser radiation pulse interactions can significantly increase noise levels, thereby obscuring data (sometimes totally) and may even damage sensitive probe and detection instrumentation. Noise effects from high energy density (approximately multiterawatt) laser pulses (approximately 300-400 ps pulse widths) interacting with thick approximately 1 mm) metallic and dielectric solid targets and dielectric-metallic powder mixtures are interpreted as transient resonance radiation associated with surface charge fluctuations on the target chamber that functions as a radiating antenna. Effective solutions that minimize atmospheric EMP effects on internal and proximate electronic and electro-optical equipment external to the system based on systematic measurements using Moebius loop antennas, interpretations of signal periodicities, and dissipation indicators determining transient noise origin characteristics from target emissions are described. Analytic models for the effect of target chamber resonances and associated noise current and temperature in a probe diode laser are described.     

基于OptiSystem的大气激光通信系统仿真研究

针对湍流大气对自由空间激光通信系统链路带来的闪烁和漂移等不良影响,利用OptisYstem建立了采用OOK调制方式的M阵列大气激光通信系统模型,对在湍流大气扰动环境下,链路SNR和BER随距离及阵列剪改变等问题进行了较为深入的研究。通过仿真分析表明,在中强起伏情况下,湍流内尺度对系统的BER具有重要影响;SNR随阵列数M的改变具有临界的d值,研究结果为大气激光通信的实际应用提供了较为重要的参考。     

对低层大气后向散射特性的测量与分析

激光导引星的亮度是决定自适应光学的系统工作状态的重要参数之一，它与大气散射和透过率等因素密切相关。为正确设计激光是引星系统提出用大气后向散射特性参数作为描述大气散射等对导引星影响的综合参数，并于１９９６年１２月首次在云南天文台对低层大气进行了后向散射特必参数测量，获得了５３２ｎｍ光的低层大气后向散射特性参数数据，并对测量结果进行了分析。     

用于高空动靶饱和损伤的地面激光的最低稳速跟踪分析

由地面激光束凝视高空动靶使其饱和或损伤的凝视时间，讨论并计算出地面伺服系统方位跟踪精度及最低稳定运动速度。 给出了地面伺服系统方位跟踪速度与高空激光束移动距离之间的关系，由此得出相应结论。     

Wave optics simulation of atmospheric turbulence and reflective speckle effects in CO2 lidar

Laser speckle can influence lidar measurements from a diffuse hard target. Atmospheric optical turbulence will also affect the lidar return signal. We present a numerical simulation that models the propagation of a lidar beam and accounts for both reflective speckle and atmospheric turbulence effects. Our simulation is based on implementing a Huygens-Fresnel approximation to laser propagation. A series of phase screens, with the appropriate atmospheric statistical characteristics, are used to simulate the effect of atmospheric turbulence. A single random phase screen is used to simulate scattering of the entire beam from a rough surface. We compare the output of our numerical model with separate CO(2) lidar measurements of atmospheric turbulence and reflective speckle. We also compare the output of our model with separate analytical predictions for atmospheric turbulence and reflective speckle. Good agreement was found between the model and the experimental data. Good agreement was also found with analytical predictions. Finally, we present results of a simulation of the combined effects on a finite-aperture lidar system that are qualitatively consistent with previous experimental observations of increasing rms noise with increasing turbulence level.