物体表面发射率的测量方法

根据测量物体表面的大气参数、环境温度、被测物体表面温度,并设置红外热像仪发射率设置为1,得出热图像温度.再利用热像仪测温原理计算出热像仪探测到的总辐射出射度,进而计算出被测物体表面发射率.为验证测量结果的准确性,将热像仪发射率设置为此计算值,根据此时的热图像温度与采用非红外测量方法得到的温度进行比较.此测量方法测试装置简单,测试程序简洁,测试结果准确.     

热像仪综述(中)

二、热像仪的组成和工作原理 1.热像仪成像的物理原理热像仪是一种成像装置。大家熟悉的照相机就是一种可见光成像装置,它的成像原理是基于目标表面的反射和反射比的差异。但热像仪与此不同,它是利用目标与周围环境之间由于温度或发射率的差异所产生的热对比度进行成像。通常,飞机、坦克等军事目标与周围     

热释电红外敏感器的温差响应特性

利用热释电红外敏感技术能够有效的探测复杂背景环境中的热目标。针对扩展目标和小目标两种情况,将目标和背景的温度差与其在敏感器处产生的有效入射辐射联系起来,对热释电红外敏感器的温差响应特性进行了研究。结果表明,在同一背景温度下,红外敏感器响应率与温差并不遵循线性关系;同一温差下,背景温度越高敏感器输出信号越大;在小目标情况下,对于给定尺寸和温差的目标,红外敏感器响应幅值随距离增大而显著减小。     

应用Vega模块的红外成像系统仿真建模方法

利用计算机仿真生成逼真、实时的红外导引头视场图像对于红外成像制导仿真具有重要的应用价值.根据红外成像理论和仿真建模特点,列举了以飞机为目标的实时图像生成系统中仿真建模的关键技术;从目标3D建模、飞机尾焰建模、目标和背景辐射建模和大气传输等几个方面阐述了红外成像建模的特点和需求;提出了应用Vega软件专用模块进行红外辐射特性建模的方法;最后给出了利用Sensor Vision模块生成红外图像的过程.目前,该方法已成功运用于某型红外目标模拟器的设计中.     

基于大气红外特征的作用距离建模与计算

红外探测装置是光电系统的重要组成部分。目标红外辐射在经过大气时与大气中的成分相互作用影响,从而导致目标红外辐射的衰减,影响了如红外探测系统、热成像系统的性能。通过研究大气环境对红外探测装置作用距离的影响,根据已有理论依据构建出大气系统对红外辐射的透射率模型;并计算出大气透射率,利用基于NETD距离模型及相关系统性能参数和指标,通过迭代计算,可求出目标与探测器之间的红外作用距离,分析计算了主要因素对作用距离的影响。该研究为红外探测系统方案设计及性能优化提供数据支撑,也为红外数字仿真系统构建提供了必要条件。     

末敏子弹的红外成像实验方法

针对红外侦查预警系统探测识别末敏弹的关键问题,采用高分辨率红外热像仪研究了一种伞降末敏子弹的红外辐射特性。通过激活末敏子弹的内部热电池,并利用红外热像仪实时监测,得到了末敏子弹的静态红外图像序列;通过在热气球上高空投放末敏子弹,同时利用热像仪实时跟踪捕获的方法,得到了末敏子弹稳定下降过程中的动态红外图像序列。对比分析了末敏子弹的静态、动态红外辐射特性,并对不同波长和斜程下的红外辐射大气透过率进行了理论计算。红外图像序列可注入红外侦察预警系统的信息处理机,从而为考核预警系统对末敏子弹的作用距离、威胁告警及其识别处理等对抗评估技术奠定了重要基础。     

烟幕对红外成像探测干扰作用研究

红外热成像探测、制导技术在现代战争中占有重要地位。通过对红外热像仪的探测原理及烟幕对红外热像探测的干扰机理研究,探讨了冷烟幕和热烟幕对红外热像仪的干扰原理。烟幕箱实验表明,红外热像的探测能力随红外烟幕质量浓度的增加而降低。冷烟幕主要是通过烟幕粒子的吸收和散射作用干扰热像仪;而热烟幕除了具有吸收和散射作用外,还通过烟幕自身发射比目标强得多的红外辐射来屏蔽热像仪,从而起到干扰作用。理论分析与实验结果具有较好的一致性。     

热成像图像与瞄准镜分划图像实时处理系统研究

热像仪(红外夜视仪)是夜战中用于观察和瞄准的重要装备.为了实现热成像瞄准镜同样具有坦克微光瞄准镜所具有的功能,本文利用数字信号处理器DSP(Digtal Signal Processors)高速图像处理功能实时地将热成像图像和瞄准镜分划图像进行叠加处理,从而解决了上述问题.     

基于OpenGL的舰船目标红外图像生成

文中基于OpenGL对舰船目标进行红外热像模拟，根据红外物理和传热学知识。综合考虑面元之间辐射、传导、对流以及面元与周围大气、海面、太阳之间的辐射、对流，建立较为完善的舰船目标红外物理模型，计算出舰船各部分的温度分布及辐射亮度分布。根据辐射亮度量化为灰度信息，经过建模、视点变换、环境设置等一系列处理并渲染输出红外图像，并利用双缓存技术实现动态红外图像的生成。     

红外探测器对飞行弹丸探测距离的仿真研究

红外系统的探测距离除了受探测器本身系统的制约之外,还受到目标辐射、背景辐射和大气传输等因素的影响。针对红外系统接收的弹丸相对辐射,提出一种新的红外系统探测距离计算模型,该模型考虑了红外系统接收弹丸辐射的等效面积辐射、弹丸周围一定范围内的等效背景辐射和大气对弹丸辐射的衰减换算。在飞行弹丸表面辐射计算的基础上,推导出新的红外系统对弹丸的探测距离计算方程,并对其进行仿真分析。     

Stability of the Third Generation Intensifier under Illumination

The stability under illumination of transmission-mode GaAs photocathode sealed in the third generation intensifier is investigated by use of spectral response testing instruments. The variations of spectral response with the illumination times under weak and intense illumination are compared. The variations of photoemission performance parameters are also characterized. The results show that during initial several weak illuminations photocathode behaves no evident decay and a maximum sensitivity is achieved, while under intense illumination the sensitivity of photocathode begin to decrease largely at the first illumination. The calculated performance parameters show that the variation of surface escape probability with illumination times is a direct cause of instability of photocathode. It is also found that under intense illumination peak wavelength is moved towards short-wave and peak response is decreased, which shows that the ability of long-wave response of photocathode is decreased.     

Passive Acoustic Radar for Detecting Supersonic Cruise Missile

A Passive Acoustic Radar is presented as a necessary complement to electromagnetic wave radar, which will be expected to be an effective means for detecting cruise missiles. Acoustic characteristics of supersonic flying projectiles with diverse shapes are expounded via experiment. It is pointed out that simulation experiment could be implemented using bullet or shell instead of cruise missile. Based on theoretical analysis and experiment, the ““acoustic fingerprint““ character of cruise missile is illustrated to identify it in a strong noise environment. After establishing a locating mathematical model, the technique of acoustic embattling is utilized to resolve a problem of confirming the time of early-warning, considering the fact that velocity of sound is much slower than that of light. Thereby, a whole system of passive acoustic radar for detecting supersonic cruise missile is formed.     

Super-resolution Restoration of Remote-sensing Images

A novel image restoration scheme, which is super-resolution image restoration algorithm Poisson-maximum-afterword-probability based on Markvo constraint （MPMAP） combined with evaluating image detail parameter D, has been proposed. The advantage of super-resolution algorithm MPMAP incorporated with parameter D lies in the fact that superresolution algorithm MPMAP model is discrete, which is in accordance with remote-sensing imaging model, and the algorithm MPMAP is proved applicable to linear and non-linear imaging models with a unique solution when noise is not severe. According to simulation experiments for practical images, super-resolution algorithm MPMAP can retain image details better than most of traditional restoration methods; at the same time, the proposed parameter D can help to identify real point spread function （PSF） value of degradation process. Processing result of practical remote-sensing images by MPMAP combined with parameter D are given, it illustrates that MPMAP restoration scheme combined PSF estimation has a better restoration result than that of Photoshop processing, based on the same original images. It is proved that the proposed scheme is helpful to offset the lack of resolution of the original remote-sensing images and has its extensive application foreground.     

Design and Simulation of TF and TA Controller for Missile

A nonlinear terrain following(TF) and terrain avoidance(TA) controller is proposed for missile control systems. Based on classical TF algorithm (adaptive angle method), a new method for TF controller is proposed by using angle of attack. A method of obtaining terrain outline data from digital elevation map (DEM) for TF control is discussed in order to save store space. A TA algorithm is proposed by using bank-to-turn technique. The block control model, which is suitable for backstepping design, is given for nonlinear model of missile. Making full use of the characteristics of the system and combining block control principle and backstepping technique, a robust controller design method is proposed. Uncertainties in every sub-block are allowed, and can be canceled by using the idea of nonlinear damping. It is proved that the state tracking errors are converged to a neighborhood of the origin exponentially. Finally, nonlinear six-degree-of-freedom simulation results for the missile model are presented to demonstrate the effectiveness of the proposed control law.     

Design and Analysis of Test Schemes of Static Postponing Time on Shrapnels Used to Riot Control

The test scheme of static postponing time given in our actual national military test standard on shrapnels used to control riot is a nine-point test scheme on the combined action of three kinds of temperatures and three kinds of pressures,the consumed ammunitions are more excessive. Statistic analysis and tentative checkout about a lot of test data are done,feasibility gists are put forward for optimizing of the test design scheme. The optimizing design and data analysis of test scheme of the item are done by managing uniformity design theory, two scientific and reasonable six-point test schemes are confirmed. The feasibility and reliability of the optimizing design schemes put forward above are proved ulteriorly by test validating. The gained schemes not only have good design uniformity and little ammunition wastage and meet the test demand, but also have better forecast ability for the result data of other points using the mathematic models from the actual test points.     

Design of Non-fragile Satisfactory Estimator for Linear Continuous Perturbed Stochastic Systems

The design problem of non-fragile estimator is addressed for a class of perturbed linear continuous systems. The perturbations occur on the plant and estimator parameters. The estimator designed should force the error system to achieve the desired decay rate and force the steady error variance less than the specified upper bound irrdevancy of the admissible plant perturbations and estimator perturbations. Consistency problem of the decay rate with the variance upper bound is first considered via linear matrix inequality （LMI） approach. The solution of the estimator parameter under specifications to be consistent is then discussed. The consistency condition of specifications and estimator parameter solution are transformed to feasible or minimum problems subject to a set of LMI respectively. The method is illustrated by a numerical example.     

An Improved Scene-based Nonuniformity Correction Algorithm for Infrared Focal Plane Arrays Using Neural Networks

The improved scene-based adaptive nonuniformity correction （NUC） algorithms using a neural network （NNT） approach for infrared image sequences are presented and analyzed. The retlna-like neural networks using steepest descent model was the first proposed infrared focal plane arrays （IRFPA） nonuniformity compensation method, which can perform parameter estimation of the sensors over time on a frame by frame basis. To increase the strength and the robustness of the NNT algorithm and to avoid the presence of ghosting artifacts, some optimization techniques, including momentum term, regularization factor and adaptive learning rate, were executed in the parameter learning process. In this paper, the local median filtering result of Xij （ n ） is proposed as an alternative value of desired network output of neuron Xij （ n ）, denoted as Tij （ n ）, which is the local spatial average of Xij （ n ） in traditional NNT methods. Noticeably, the NUC algorithm is inter-frame adaptive in nature and does not rely on any statistical assumptions on the scene data in the image sequence. Applications of this algorithm to the simulated video sequences and real infrared data taken with PV320 show that the correction results of image sequence are better than that of using original NNT approach, especially for the short-time image sequences （several hundred frames） subjected to the dense impulse noises with a number of dead or saturated pixels.     

Piecewise Filter of Infrared Image Based on Moment Theory

The disadvantages of IR images mostly include high noise, blurry edge and so on. The characteristics make the existent smoothing methods ineffective in preserving edge, To solve this problem, a piecewise moment filter （PMF） is put forward. By using moment and piecewise linear theory, the filter can preserve edge. Based on the statistical model of random noise, a related-coefficient method is presented to estimate the variance of noise. The edge region and model are then detected by the estimated variance. The expectation of first-order derivatives is used in getting the reliable offset of edge. At last, a fast moment filter of double-stair edge model is used to gain the piecewise smoothing results and reduce the calculation. The experimental result shows that the new method has a better capability than other methods in suppressing noise and preserving edge.     

Bistatic Sonar Localization Based on Best Linear Unbiased Estimation

A best linear unbiased estimation （BLUE） algorithm for bistatic sonar localization is proposed. The Cramer-Rao bound for bistatic Sonar and the geometrical dilution of precision （GDOP） in different conditions are given. The simulation results show that the location accuracy of BLUE algorithm is higher than the weighted least square method.     

Research on Gear-broken Fault Diagnosis in a Tank Gearbox

A fault diagnosis method of working position gear in a tank gearbox is put forward based on simulating the fault of working position gear in an actual tank, extracting the envelope of vibration signal by Hilbert transformation amplitude demodulation method, and zooming the low-frequency band to envelope signal.