电视观瞄/可见光直视观瞄光学系统设计

随着车载光电系统的发展,多功能合一的观察瞄准镜成为发展趋势。将电视观瞄/可见光直视观瞄系统进行共光路设计,可见光直视观瞄系统放大倍率为8×、视场为5°、出瞳直径为φ4 mm、出瞳距离不小于15 mm;电视观瞄系统F数为6、焦距为110 mm。同时,对设计结果进行公差分析,根据公差分析结果制定严格的零部件加工公差及系统装调方案,系统结构紧凑,成像良好,对2.3 m×2.3 m的目标进行观瞄,识别距离大于4 km,满足指标要求。     

室内直达与非直达环境无线传播综合信道建模

本文主要针对室内无线传播信道直达(line of sight, LOS)与非直达(no line of sight, NLOS)环境, 引入参考模型研究其建模设计及其相关统计特性. 文中提出了一种基于几何散射模型的综合改进室内参考信道模型, 假设将无限数量的散射体均匀分布在三维空间的一个二维(two dimensional, 2D)水平面上. 本文推导了电磁波达信号到达角(angle of arrival, AOA) 概率分布函数(probability density function, PDF)、多普勒功率谱密度(power spectral Density, PSD)、 时间自相关函数(autocorrelation function, ACF)的解析表达式, 并分析其重要参数对函数的影响. 此外, 本文还通过非现实参考模型提出了一种高效的SOC(Sum of Cisoids) 信道仿真模型, 同时提出了设计SOC信道仿真模型的两种有效参数计算方法, 并比较两者的计算性能. 仿真结果表明, 信道仿真模型的统计特性与参考模型相匹配, 即室内参考模型可以通过的SOC信道仿真模型来近似, 同时信道仿真模型可以很好的应用于评估室内无线通信系统的性能, 拓宽了室内无线信道建模的研究, 同时减少实现开支.     

光电稳瞄系统装调的关键技术

鉴于光电稳瞄系统的复杂性和科研开发的不可预见性，传统装调技术远不能满足产品科研设计发展的需求。着重分析探讨了光电稳瞄系统中各探测器光谱范围的差异性、光学平台结构的复杂性、光学轴系与回转轴系的一致性带来的精度难以实现的关键技术问题。通过多组自准直仪架设空间过渡基准，采用特定的大口径光轴调校装置，解决了光轴平行性调校问题。以调校光学轴系与机械回转系统的同步精度为出发点,确定了各部件之间的装配及装配误差的影响。通过设计的方位/俯仰天顶测量仪，解决了回转轴系正交性精度调校难题，实现了传统工艺方法和普通调校装置无法达到的设计指标和精度要求。     

Beyond the elliptic genus

Given a Riemann surface Σ and a Riemannian manifold M with certain restrictions, we construct a cobordism invariant of M. This invariant is a generalization of the elliptic genus and it shares some similar properties.     

Beyond the x-K relations

Explicit formulae are given for all off-diagonal 1–1 and 2–2 resonance terms in the vibrational hamiltonian following the first contact transformation. Such formulae are needed to test the quantitative accuracy of the generalized x-K relation recently published by Della Valle. These formulae are used in a test calculation for linear HCN and DCN and are found only modestly to improve the predicted energy levels for the former, but dramatically improve those of the latter.     

稳瞄惯导周视观瞄镜的设计

介绍一种中精度、低成本周视观瞄镜的设计方法，其特点是用一个机械陀螺同时实现稳瞄和惯导2项功能。利用陀螺罗经原理，使机械陀螺的敏感轴快速收敛于子午面和水平面的交线上，并借助陀螺定轴性和2自由度环架，使陀螺隔离运动载体的扰动；通过环架上的光电传感器测出运动载体的姿态角，使观瞄镜的瞄准线随动于陀螺的敏感轴，实现间接稳定。在瞄准过程中，瞄准线的调转指令以随动修正量的形式加入，通过姿态矩阵的解算，可获得运动载体扰动量沿稳瞄坐标轴方向的投影，即瞄准线随动陀螺轴的输入量。最后综合运动载体的姿态和里程计信息，可以实现导航功能。     

直升机载光电稳瞄系统可靠性研究与分析

 稳瞄系统可靠性对直升机载武器系统可靠性具有重要影响。通过对产品可靠性概念和军用光电系统可靠性、直升机载稳瞄系统的功能和组成单元的阐述,给出了舰载直升机光电稳瞄系统的可靠性框图和数学模型。研究了舰载直升机稳瞄系统的可靠性影响因素和系统故障模式,探讨了稳瞄系统结构、光学和电气可靠性,提出通过计算机仿真对稳瞄系统可靠性进行预计分析的方法。某舰载直升机稳瞄系统在96 h可靠性试验过程中出现故障2次,达到MTBF≤32 h的可能性指标要求。对系统可靠性提前进行预估并采取相应的设计措施,保证产品可靠性达到设计要求,提高设计质量,缩短研制周期。     

无透镜傅里叶变换型全息瞄准具研究

基于无透镜傅里叶变换全息术制作了一种新型激光全息瞄准具。瞄准具的核心部件是由一块无透镜傅里叶变换位相全息图和一块全息光束变换器组成的全息光学元件。其突出优点是大视场,大出瞳距离,适合双眼瞄准。此外,瞄准线为明亮的虚像,不会暴露目标,结构简单,对射击近距离运动目标效果突出。介绍了全息瞄准具组件的原理和制作方法,并对其性能进行了分析。     

改善光电稳瞄系统视觉效果的图像增强算法

为了改善光电稳瞄系统的视觉效果,使视频图像更加适合于人眼观察,并且有利于对目标的自动跟踪效果,将直方图均衡化处理与拉普拉斯边缘锐化处理相结合,在增强对比度的同时尽量保持边缘细节。仿真结果显示采用本文算法能够有效改善视频图像的视觉效果。     

Euler Products Beyond the Boundary

We investigate the behavior of the Euler products of the Riemann zeta function and Dirichlet L-functions on the critical line. A refined version of the Riemann hypothesis, which is named “the Deep Riemann Hypothesis”, is examined. We also study various analogs for global function fields. We give an interpretation for the nontrivial zeros from the viewpoint of statistical mechanics.     

The benefit of practice for sound localization without sight

An experiment was designed to determine whether normally sighted human subjects would be able to adapt to the handicapping effects of sudden deprivation of visual cues on horizontal plane sound localization. Two groups of sighted normal-hearing young adults participated. One group was allowed the benefit of sight. The other group was blindfolded. Measurements of accuracy and the time to respond were made daily over the course of five consecutive days, in a semi-reverberant sound proof booth that modeled listening in a small office. Sound localization was assessed using an array of eight speakers that surrounded the subject in space. Each day, one block of 120 trials was presented for each of three stimuli, two one-third octave noise bands, centred at 0.5 and 4 kHz, and broadband noise, to assess the utilization of interaural temporal difference cues, interaural level difference cues and binaural and spectral cues in combination. Blindfolded subjects were relatively less accurate than sighted subjects. Both groups showed gains with practice, the blindfolded group to a greater degree, largely due to improvements in the use of spectral cues. The blindfolded group took longer to respond than the sighted group, but showed greater decrements in response time with practice.     

某型号周视镜总体设计技术分析

为了扩大观察范围,模块化结构单元,提高可靠性,设计了一款多功能周视镜。利用滚珠丝杠和直线轴承实现头部升降,扩大产品的观察范围;利用齿轮组差动技术实现上反射镜运动传输,保证系统可靠性;利用步进电机驱动道威棱镜及配合绝对值式光电编码器反馈角值位置信息,消除周视过程中的图像旋转,保证系统观瞄和测角精度。实验结果表明:周视镜可昼夜观瞄、昼间3～6连续变焦、头部升降300 mm、方位向全周视、测角精度在连续转动下不低于1 mard。     

蹦床谐振器感知极弱的机械力

历史已经证明,拥有制作更好传感器的能力,将有助于开拓新的物理实验。反之,新的实验又会促进开发更好的传感器。在机械工程和量子物理学的交叉领域,研究人员正在使用纳米刻蚀工具,制作新一类基于机械谐振器的传感器。通过制备具有精细机械性能和光学性能的薄膜,两个研究组现在已经展示了“蹦床谐振器”,它能分辨极其微弱的力(~16×10^－18 N,这个力的大小就相当于人与人之间相距100 km时的引力),并且在室温环境中展现出量子运动。     

Temporal onset-order discrimination through the tactual sense

Tactual temporal-onset order thresholds were measured for two sinusoidal vibrations of different frequencies delivered to two separate locations (thumb and index finger) of a multi-finger tactual stimulating device. The frequency delivered to the thumb was fixed at 50 Hz and that to the index finger at 250 Hz. The amplitude and duration of each of the two sinusoidal vibrations were roved independently from trial to trial in a 1-interval, 2AFC procedure. Performance, measured as a function of stimulus-onset asynchrony (SOA), indicated that the temporal-onset-order threshold averaged 34 ms across four subjects. The data were further classified into subsets according to both the amplitude and duration of the two stimuli in each trial of the roving-discrimination paradigm. The results indicated that the amplitude differences of the two stimuli in each trial had a substantial effect on onset-order discrimination, while duration differences generally had little effect. The effects of amplitude differences are explained qualitatively in terms of amplitude latency relationships and stimulus interactions such as temporal masking. Overall, the results not only contribute to an enhanced understanding of the temporal sensitivity of the tactual system but also provide guidelines for the design of tactual aids for hearing-impaired persons.     

非制冷热像观瞄系统动态目标的智能检测

为了适应实时性的要求,在目标检测及定位时对处理方法的简洁性提出了很高的要求。基于热像观瞄系统,根据观瞄的目的,介绍了一种具有一定大小的目标检测方法。根据差分图像像素特性,提出了自适应选取阈值的新方法,对目标像素的亮度和分布密度进行精确定位。这种方法充分考虑了像素的自身属性信息,便于硬件的实时处理。该方法可以达到较高的检测率。