目标红外迷彩伪装技术研究

随着红外迷彩伪装涂料的出现,利用其对目标红外热图像进行分割,破坏目标图像特征的特点,为目标红外对抗提供了一种新的有效手段.首先,以传热模型为基础,模拟出目标的表面温度,并通过实测得出背景的表面瞬态温度.然后,利用随机生成的方法,生成背景的红外纹理图像.最后,以目标与背景的辐射对比度为基础,对红外迷彩涂料的设计参数进行了优化,分析了红外迷彩涂料的设计参数和图案设计对目标伪装效果的影响,达到了较好的红外伪装效果.     

Characterization of acoustic streaming and heating using synchronized infrared thermography and particle image velocimetry

Real-time measurements of acoustic streaming velocities and surface temperature fields using synchronized particle image velocimetry and infrared thermography are reported. Measurements were conducted using a 20 kHz Langevin type acoustic horn mounted vertically in a model sonochemical reactor of either degassed water or a glycerin-water mixture. These dissipative phenomena are found to be sensitive to small variations in the medium viscosity, and a correlation between the heat flux and vorticity was determined for unsteady convective heat transfer.     

An Infrared Image Synthesis Model Based on Infrared Physics and Heat Transfer

Most of current image synthesis models are based on optics of visible-spectrum. While simulating the illumination effect of visible light, they cannot show the infrared signature of the objects. This paper presents a synthesis model for generating realistic infrared images. We first establish a heat equilibrium equation of the object surface. Then according to it and the heat transfer inside the object and on the boundary surface of the object, we compute the temperature and radiometries of each surface patch of the object. Finally on the basis of the radiometries, each patch is drawn by Gouraud Shading. Experimental examples of the generated infrared images are presented, which illustrate the potential of our method.     

红外辐射场理论模拟中的普适性模型研究

在现有海面目标红外辐射场理论建模工作的基础上建立了具有普适性意义的海面目标红外辐射场理论建模通用框架,重点对建立目标的几何构型、适用于各种微元的物理模型、及通用的三维数据场可视化这三个问题进行了叙述。所得结果不仅对海面各种目标红外辐射场的计算机模拟研究具有普遍的意义,且对空中、陆地及其他场景中目标的红外辐射场理论建模研究也有一定的借鉴作用。     

空间目标抖动状态红外图像仿真建模研究北大核心CSCD

空间目标容易受到太空垃圾碰撞及干扰从而产生抖动。针对空间抖动目标红外图像的模型构建问题,对天基空间红外成像系统的主要噪声进行分析并考虑杂散光影响,基于Creator与Vega软件平台相结合,提出抖动状态下空间目标表面缺陷的红外图像的建模方法。依据空间目标基本特征分析其红外辐射特性,在Creator中对空间目标缺陷进行三维建模;根据目标以及背景红外辐射特性对三维模型进行温度场分析,将分析所得结果与Vega红外模块相结合获得红外图像模型;确定抖动图像数学模型并对仿真图像施加抖动影响,然后施加杂散光影响获得最终模拟图像。实验结果表明:该方法生成的抖动状态下空间目标红外图像与实验图像相似程度高,能为空间目标探测与态势感知提供一种有效的模拟系统。     

水面航行潜艇红外特征模拟研究

潜艇的红外辐射特征是红外探测系统发现潜艇并进行跟踪的依据,研究潜艇红外特征模拟方法对潜艇探潜和修正对敌潜艇制导数据具有一定参考价值。从潜艇的外部环境出发,分析了影响水面航行潜艇红外特征的多种复杂因素,建立了传热模型,给出传热边界方程,模拟了潜艇表面红外特征,估算了探潜距离。     

基于LLE的红外成像彩色化处理算法研究

针对红外图像对比度低、细节较差,且一般是黑白图像,不适宜于人眼观察,提出一种利用局部线性映射方法（LLE）的红外成像彩色化方法。该方法寻求灰度空间到色彩空间的映射,实现红外图像到彩色红外图像的转变,先将目标红外图像和彩色模板图像转换至YUV颜色空间,分离亮度和色彩信息;然后将目标红外图像的每个像素及邻域像素的灰度值串接成矢量,并均匀从彩色模板图像选取部分像素按相同方法串接成矢量,采用欧氏距离搜索最近邻并计算最佳的匹配系数,经色彩值（即U和V分量）计算将模板图像的彩色传递给目标红外图像后搜索亮度最大值的像素邻域并经自动阈值伪彩色编码处理,突出显示重要目标,得到处理后的彩色红外图像。将算法应用于实验室自主开发的热像仪,算法作用后的红外图像不但有了适于人眼视觉的彩色信息,而且用红、黄等敏感色突出了重点热目标,提高了人眼发现和识别目标的速度,实验结果表明,算法有利于侦察人员长时间的目标观察和识别目标。     

热声热机热声核内传热与流动特性实验研究

本文通过搭建扬声器驱动的热声热机可视化实验台,利用粒子成像测速仪(PIV)和红外热像仪得到冷、热端换热器间速度及温度场分布,对有无声场两种情况下热声核中速度及温度场的变化进行了实验研究。实验结果表明,外加声场改变了热声核中热对流的基本模式,增强了冷热端换热器间的换热能力,对热声核中的温度分布有着显著的影响。揭示了热声核中的流动与换热规律。     

零视距地物长波红外特征场景仿真研究

为仿真地物长波红外场景图像,根据地表温度随时间变化的规律,并结合气象状况、背景材质、热特性参量、热状态等参数,在对太阳辐射、大气长波辐射、大气温度和地表热传导等影响地表温度变化的因素进行分析的基础上,建立了基于热平衡理论和热传导过程的方程。解算出多种常见地表一日之中的温度变化情况,并将其应用于由相同景物可见光纹理图像反演出的相应红外纹理图像中。在考虑景物表面自身发射、反射的辐射计算模型的前提下,生成了具有相似红外纹理细节的地表红外场景。结果表明,该方法可生成接近真实感的红外场景,有效地模拟仿真地物的长波红外特征。     

近高超声速高温蓝宝石窗口下中波红外成像退化分析仿真与性能测试实验

本文基于高温红外窗口热辐射红外成像探测器干扰机理,开展高温红外窗口成像分析、仿真与实验验证研究工作. 根据流体仿真计算获得的高温窗口温度及实验测得的窗口发射率、吸收率等参数,开展窗口热辐射计算;建立了光学窗口介质内部辐射传输路径和强度计算模型,并给出了窗口辐射出射模型以及相应红外成像模型;基于光学追迹方法,把窗口热辐射成像的计算问题转换成了光学计算问题;设计了一种基于高温蓝宝石红外窗口的加热实验,对红外成像仿真结果进行了检验. 通过仿真结果与窗口加热实验结果对照,将基于模型分析获取图像与实验结果图像作差,得到的平均每个像素误差值为0.45;实验发现在窗口约773 K条件下,设计的中波红外成像系统的信噪比、对比度分别降低到原来三分之一左右,而整个红外成像系统NETD值由原来的约52 mK上升到了954 mK. 本文提出的窗口热辐射分析方法可以有效估计窗口热辐射对中波红外成像的影响,设计的实验对成像系统的指标验证有较好的用途,同时对红外成像系统波段细化优选和成像参数调整,降低图像退化程度,都有着重要的指导意义. 关键词： 近高超声速 高温蓝宝石窗口 气动效应 仿真与实验     

Heat transfer and fluid flow of benard-cell convection in rectangular container with free surface sensed by infrared thermography

The natural convection flow phenomena that occur inside an enclosed space are very interesting examples of complex fluid systems that may yield to analytical, empirical and numerical solutions, and many reports have looked into this basic problem. In the present study, heat transfer and fluid flow for natural convection in a horizontal rectangular container with a free surface are investigated using infrared thermography. The temperature field was measured and visualized at a gas-liquid (air — silicon oil) interface using infrared thermography. The heat transfer phenomena were also investigated by statistically analyzing the temperature data. The applicability of the infrared thermography to quantitative heat transfer measurement at the gas-liquid interface was evaluated. It is revealed that infrared thermography is effective not only in visualization of a gas-liquid interface but also in heat transfer measurement. A new heat transfer correlation is proposed for the gas-liquid interface of this flow system. The coefficient of heat transfer can be summarized by a specific heat transfer correlation formula regardless of several conditions, including container aspect ratio, fluid viscosity and fluid layer depth.     

Acoustic quasi-holographic images of scattering by vertical cylinders from one-dimensional bistatic scans

When synthetic aperture sonar (SAS) is used to image elastic targets in water, subtle features can be present in the images associated with the dynamical response of the target being viewed. In an effort to improve the understanding of such responses, as well as to explore alternative image processing methods, a laboratory-based system was developed in which targets were illuminated by a transient acoustic source, and bistatic responses were recorded by scanning a hydrophone along a rail system. Images were constructed using a relatively conventional bistatic SAS algorithm and were compared with images based on supersonic holography. The holographic method is a simplification of one previously used to view the time evolution of a target's response [Hefner and Marston, ARLO 2, 55-60 (2001)]. In the holographic method, the space-time evolution of the scattering was used to construct a two-dimensional image with cross range and time as coordinates. Various features for vertically hung cylindrical targets were interpreted using high frequency ray theory. This includes contributions from guided surface elastic waves, as well as transmitted-wave features and specular reflection.     

舰船红外热像的软件模拟

在建立了合理的舰船传热学模型之后，就要进一步完善舰船热像模拟的理论模型，较为完整地考虑周围环境对物体及物体各部分之间的相互作用，包括太阳辐射、海／天背景辐射、海／空气的对流以及船体各部分的传导和相互辐射。利用计算机技术和面向对象编程方法实现了船体的红外辐射热像与海洋及天空等背景辐射的初步耦合、显示和包括图像储存在内的较完整的热像模拟软件。应用ＶｉｓｕａｌＣ＋＋语言编写，软件具有友好的用户界面和良好的可扩充性，易于维护。     

地面目标动态红外特征模拟与隐身技术的研究

针对易受敌方红外制导武器攻击的地面军事目标,模拟并计算出其红外辐射特征。通过合理的假设,将复杂的三维辐射与对流耦合传热问题简化为一维瞬态传热问题,运用多层有限差分的数值计算方法计算模拟出目标瞬时温度变化方向图,得出其动态红外特征。在此基础之上,分别研究了地面目标不同部位(顶部与侧面)隐身所需要的表面发射率与温差的关系。分析了在不同温差条件下目标隐身所需表面发射率随时间的变化关系。计算模拟得出目标与背景在一日之中都存在明显的温差,最大温差可达10℃左右。分析得出利用水雾隐身使目标与背景的温差控制在2℃以内可达到良好的隐身效果。     

One color contrast enhanced infrared and visible image fusion method

Color constancy (Toet and Franken, 2003 [2]; Toet, 2003 [7]) and color contrast (Scribner et al., 2000 [21]; Lee et al., 2005 [23]) are two important topics for color image fusion. The paper focuses on the low color contrast problem of linear fusion algorithms with color transfer method. Color transfer technology is popular in infrared (IR) and visible image fusion to give the fused image a natural day-time color appearance (Toet, 2003 [7]; Wang et al., 2007 [8]; Zheng and Essock, 2008 [9]). However, in the color transfer step, all three channels of the color space are processed with the same linear mapping without color enhancement, resulting in low color contrast between the target and the background (Wang et al., 2007 [8]). Based on the characteristics of the IR image, we introduce a ratio of local to global divergence of the IR image to improve the color contrast. The enhancement ratios for both hot and cold targets are larger than one, while it tends to one for the background. As a result, the proposed method pops out both hot and cold targets in color, where hot targets will appear intense red, and cold targets will appear cyan. Subjective results show visible color contrast enhancement effects. Target detection experiments through hue and saturation components of the fused image show an improvement in the hit rate for target detection, owing to larger color distance between the target and the background.     

Natural and forced convective heat transfer on slender cylinders

This paper presents an experimental study of free and forced convective heat transfer along vertical slender cylinders. The local heat transfer coefficient is determined from the measurement of the surface temperature distribution performed by quantitative infrared thermography. It is found that the convective heat transfer is strongly dependent on the cylinder curvature and misalignment with the flow. The effect of proximity of two cylinders is emphasized in the case of forced convection. Correlations are proposed for the two types of convection. It is worth noting that circumstances exist where the turbulent heat transfer in free convection can be of the same order of magnitude as for laminar forced convection. The outcome of the study demonstrates the suitability of quantitative infrared thermography to solve complex problems and to provide a deeper understanding of the heat transfer on slender cylinders.     

舰船尾迹和海面红外仿真成像

舰船在军事领域有着极其重要的地位,其尾迹对海面的温度和高度都会造成相较明显的变化,且具有持续时间长、不易消除等特点,所以模拟舰船尾迹和海面红外辐射图像可以更为直观地识别舰船目标,具有强烈的军事需求。以MODTRAN软件模拟的不同背景环境下大气对8μm～14μm波段的透过率为数据基础,结合Cox-Munk坡度概率分布模型并考虑海浪遮挡因素建立了一种舰船尾迹红外辐射模型,模拟了不同背景环境、不同探测距离的红外尾迹图像。仿真结果表明：相同探测条件下,随着探测距离增大,舰船尾迹辐射亮度减小,但粗糙海面对红外辐射的遮挡作用显著减弱,海面舰船尾迹更易被识别;大气传输模型对红外成像结果影响较大,夏季背景辐射能量大且海面平均遮挡作用小,舰船尾迹红外成像更为清晰。     

建筑物温度场理论建模研究及逐时计算

建筑物温度场计算是目标红外图像理论建模的基础,本文研究了建筑物外表面温度场理论模型的建立,探讨了蒙特卡罗法在求解建筑物表面辐射传递系数中的应用,文中以哈尔滨市最高建筑物华融大厦为对象,逐时、逐季节计算了其辐射传递系数及温度场分布,阐述了模型的合理性。     

基于散射介质成像理论的微光夜视系统研究

描述了一种基于大气散射特性分析的微光夜视系统设计。通过分析大气对光学辐射的散射作用,在理想光电成像系统探测方程的基础上,建立了散射介质成像的探测模型,表明大气散射会严重衰减目标对比度,而目标对比度的传递特性即系统调制传递函数将直接影响观察的作用距离。通过选择应用响应光谱主要集中于0.6μm~1.0μm的三代像增强器,优化设计光学系统的MTF,实现了大气环境下的微光系统作用距离的提高。完成的两种焦距分别为250mm和320mm,采用了三代像增强器的夜视仪.野外试验表明,实现对空目标作用距离最大13.7km~18.3km发现、8.0km~8.1km识别。