复合测温传感器的积分发射率研究􀀂

复合测温传感器所形成的实际黑体空腔具有"不等温"和"非密闭"的特点,其积分发射率不能简单看作1.为此,我们给出了不等温积分发射率的计算公式,并分析了传感器几何特性、温度分布、材料发射率、腔口与探测器之间的距离和环境温度对积分发射率的影响,为实现传感器的优化设计和提高准确度奠定基础.     

发射率可变非等温圆筒形空腔的有效发射率计算

从理论上计算了非等温圆筒形空腔的有效发射率,并证明了空腔积分发射率的可变性。文中对非等温空腔辐射换热积分方程的建立及求解、空腔一探测器系统及其计算方法,均作了较为详细的分析和讨论。     

Monte-Carlo法的黑体腔高温传感器有效发射率研究

基于Monte-Carlo法建立了圆筒形黑体空腔模型,对黑体空腔模型的有效发射率进行计算,分析了不同腔体几何结构、腔体材料发射率、探测器距腔口距离等因素对黑体腔有效发射率的影响,并与有限元分析法所得结果进行对比.结果表明:由Monte-Carlo法得到的结果与有限元分析法基本符合,即长径比较大、孔径比较小、腔体材料发射率较大时,黑体腔有效发射率较大.     

复合温度传感器有效发射率影响因素分析

为消除复合温度传感器所形成的在线黑体空腔"不等温性"和"非密闭性"对测量的影响,采用矩形区域近似法进行了不等温有效发射率的计算。在分析传感器几何特性、材料发射率、温度分布和环境温度对有效发射率影响的基础上,给出了传感器结构的优化参数。实验表明:优化后的传感器具有较高灵敏度和准确度。     

中温黑体炉结构及其有效发射率的计算

黑体辐射源(黑体炉)广泛用于分度各种辐射温度计和作为测量各种物质发射率的标准辐射源。本文结合作者近期的实验和计算介绍了陶瓷圆筒形腔体中温黑体炉和不锈钢圆筒形腔体红外标准辐射源的结构及其特性,并提供了这两种圆筒形黑体空腔有效发射率分布的计算结果。     

基于GA-WNN温度补偿的红外CO2气体传感器系统研究

为了提高红外CO2气体传感器的探测灵敏度和精度,首先基于计算流体动力学（CFD）仿真计算,研究了传感器腔内气体辐射功率吸收效率与腔体结构之间的关系,模拟结果表明：当圆柱腔体的直径与内壁反射率固定时,腔体结构存在最佳腔长可使传感器红外辐射功率吸收效率达到最大。然后基于CFD仿真的结果设计和实现了CO2气体传感器,并开展了实验比对与验证,进而着重研究了环境温度对气体测量结果的影响。实验结果表明：在5~45oC温度范围内,传感器在0~2000 ppm浓度范围内的测量误差随着温度升高而显著增大。最后采用遗传小波神经网络算法（GA-WNN）对传感器进行了温度补偿,数据融合补偿后传感器的温度漂移得到了较好的抑制,其绝对误差小于±70 ppm,在非样本温度点下,整体平均误差小于±100 ppm,表明CO2气体传感器的测量精度得到了较好的提升。     

黑体空腔单波段有效发射率分布的计算

本文应用计算黑体空腔有效发射率分布的新方法——矩形区域近似法.计算了带盖锥柱形黑体空腔等温和不等温分布时,腔内的单波段有效发射率εa(λ,To,X)分布,并且同 Bedford's 方法的计算结果进行了比较,比较结果看出两者是一致的。这证明了矩形区域近似法是一种精确计算法,而且矩形区域近似法在计算中避开奇点的处理问题,从而使问题充分简化,且计算时间少,占机内存容量小,编制和调试程序容易.     

一种新型光纤高温传感器及其测模的研究

提出的光纤高温传感器解决了辐射测过程中固体发射率的瞬态变化影响的问题并对测量系统的误差进行了分析，也给了实验结果。     

CCD辐射测温的数值解析及误差校正

提出一种新的CCD辐射测温数值校正方法。针对CCD测温时的两个主要误差来源(CCD光谱响应曲线和辐射体光谱发射率)进行了分析,运用图象处理技术对CCD光谱响应曲线进行离散化数值解析,借助比色测温原理标定并解析辐射体光谱发射率,建立了CCD辐射测温校正公式,实验数据表明测温方法及误差校正的有效性。这种测温方法是由CCD图像传感器对辐射体直接采集成像,在工业现场可摈弃附加外设的繁琐和不便,为辐射测温系统的便携性、实用化创造了条件。     

辐射温度测量近况

1.发射率发射率ε是波长λ和温度 T 的函数。在某一波长和温度下物体的光谱辐射亮度L_(λ.T)可用下式表示:L_(λ.T)=ε(λ,T)·L(λ.T)这里,L_((λ.T))是完全辐射体的光谱辐射亮度,ε(λ·T)是该物体的光谱发射率。实际使用时,用有效波长代表波长,把发射率看作是温度的函数,然而最基本而重要的还是光谱发射率。不仅以各种金属为中心不断地进行了光谱发射率的测定和理论的探讨,而且最近还扩展到了金属氧化物和非金属材料的对象中。(1)金属的发射率     

红外辐射温度测量技术讲座──第二讲 黑体传感器

介绍了黑体定义的一般概念，基尔霍夫黑体的物理模型，黑体辐射源的分类及光纤黑体传感器。同时介绍了实验室用黑体辐射源和在线黑体辐射源的主要特征，黑体空腔有效发射率分布及黑体空腔精度等级的计算。     

基于有限元法的黑体腔高温传感器动态特性分析

基于有限元热分析法,建立了黑体腔三维有限元模型,分析了黑体腔结构参数、热物性参数、黑体腔初始预热温度对黑体腔测温过程中动态特性的影响。研究结果表明：黑体腔结构参数的改变直接影响黑体腔动态测温误差、动态响应时间、腔体发射率,进而影响黑体腔性能。黑体腔动态测温误差随着比热或密度的增大而增大。黑体腔初始预热温度对黑体腔动态测温影响较大,初始预热温度每增加100℃,最大测温误差减小50℃左右,动态响应时间减少5 s左右。     

Definition of component effective emissivity for heterogeneous and non-isothermal surfaces and its approximate calculation

Measurement of land surface temperature faces many problems. For example, each pixel over land surface is likely to be heterogeneous and non-isothermal with both vegetation canopy and background soil, and the three-dimensional structure of canopy often makes the canopy radiation angular dependent. It is difficult to define an overall land surface temperature and emissivity at pixel scale for heterogeneous and non-isothermal surfaces. After recalling several definitions of effective emissivities, component effective emissivity is defined in this paper under the conditions of local thermal equilibrium and a constant material emissivity for surface temperature variation in the normal Earth environment. Component effective emissivities make it possible to retrieve the component temperature based on multi-directional measurements. The sum of component effective emissivities is equal to the overall effective emissivity, which can be used to inverse pixel-averaged effective temperature. Taking the continuous plant/soil system as an example, the Monte Carlo method is used to simulate the effective emissivities, and an analytical expression equation (AEE) of the effective emissivities including direct-line emission and single scattering contribution is developed. Monte Carlo simulated results show that the sum of direct-line emission and single scattering effective emissivity is close to overall effective emissivity when soil and leaf are set to 0.94 and 0.98 respectively. Then component and overall effective emissivities calculated by Monte Carlo method and AEE are compared, and their differences are analysed for different soil and leaf emissivities. It is shown that when soil and leaf emissivities are set respectively to 0.94 and 0.98, the differences are less than 0.006 within a 50° view zenith angle. When soil or leaf emissivity is set to 0.9, the difference reaches 0.025 or 0.016, which is large enough to introduce a 1?K error in land surface temperature inversion when this effective emissivity is used. The paper finally proposes that the linear relationship of difference with soil and leaf emissivity can be used to compensate the errors.     

瞬态高温测试中蓝宝石光纤传感器的误差补偿

蓝宝石光纤温度传感器是一种利用蓝宝石单晶光纤端部镀以Pt,Ir等贵金属或耐高温陶瓷薄膜做为光纤传感头的新型传感器,这种方法基于黑体辐射原理。为了解决瞬态高温测量中存在的非线性误差问题,分析了蓝宝石光纤温度传感器的黑体辐射原理和非线性误差的来源,给出了温度误差的修正方法,并利用标准红外辐射测温仪进行温度校正。校正后的结果能够满足实际测温需求。     

光纤黑体空腔光电高温计的研制

光纤黑体空腔光电高温计的特点是在普通光电高温计前设置黑体空腔。前呈黑体空腔的精度是此类仪表的关键问题。在生产现场测量了两种类型在线黑体空腔的温度分布，计算了其有效发射率分布，并评价了上述肢体的精度等级。该光电高温计采用＊G－51系列单片机作为信息处理单元，结果表明，性能稳定可靠。     

Identification of plant species by using high spatial and spectral resolution thermal infrared (8.0-13.5 μm) imagery

High spatial and spectral resolution thermal infrared imagery (8.0-13.5 μm) from the SEBASS airborne sensor was used to analyze and map tree canopy spectral features at the State Arboretum of Virginia, near Boyce, Virginia. Fifty tree species were analyzed and about half were directly identified with varying degrees of success on the basis of spectral matched filtering that utilized laboratory-measured leaf spectra as the target signatures. Spectral averages of pixels extracted from SEBASS emissivity data compared favorably with laboratory spectra of leaves collected from individual tree species. Best results were obtained from species having relatively strong spectral contrast, wide and flat leaves, closed planophile canopies, and/or large canopy areas. Tree species having small leaves or unfavorable leaf orientations showed spectral attenuation likely resulting from cavity blackbody effects. Increased spatial resolution and better image calibration and atmospheric correction might lead to further improvements in thermal infrared plant species identification.     

The determination of the effective ambient temperature for thermal flow sensors in a non-isothermal environment

Thermal flow sensor behaviour is investigated for the condition that the direct surrounding of the sensor, such as the plate on which the sensor is mounted, is at a temperature that is different from that of the flow. In that case the convective heat transfer depends on the difference between the (average) sensor temperature and the effective ambient temperature, where the latter is a weighed average of the plate and fluid temperatures. Knowledge of which temperature level represents the true effective ambient value is vital for a correct design and operation of a thermal flow sensor. In the present theoretical study this ambient-temperature weighing effect is examined by investigating the weighing function for the laminar heat transfer from a sensor mounted on a plate where (a part of) the upstream plate length is at a constant temperature which is different from that of the flow. The analysis reveals how the weighing effect, and hence the effective ambient temperature, depends on the non-isothermal upstream length, and that this dependence is significantly different for sensing methods that rely on either total or differential convective heat transfer.