Application of dual-wavelength radiation thermometry to the aluminum industry

The objectives of this paper are to introduce the basic principles of dual-wavelength radiation thermometry, to show their utility in inferring temperature, and to investigate the influences of time-at-temperature and temperature on the emissivity behavior of selected aluminum alloys in their processing conditions. Thirteen algorithms are mentioned in this paper, and the results from six of them are reported. Experimental procedures and apparatus are described. The emissivity behavior as a function of time correlated fairly well with the results of Cochran and Sleppy. The ISS algorithm is capable of inferring temperature to within ± 1.6 K. Thus, it is recommended that the ISS algorithm be used for measuring the temperature of 5052 aluminum alloy extruded samples.     

Methodology for spectral emissivity measurement by means of single color pyrometer

The application of non-intrusive optical devices, such as infrared pyrometers able to measure the temperature of surfaces, makes possible the evaluation of emissivity curve of the tested materials at different temperature values. In this paper the authors propose a methodology for the spectral emissivity measurement by means of a single color pyrometer providing a semi-empirical formula, obtained experimentally at CIRA’s laboratory. The semi-empirical formula allows to know the actual emissivity value of the sample’s surface for whatever emissivity value set up on the pyrometer. The agreement between the experimental emissivity and the emissivity predicted by semi-empirical formula was verified.     

Ultrasonic tomography based temperature distribution measurement method

The temperature distribution information plays an important role in industrial applications. Owing to the advantages such as non-intrusive sensing and low cost, the ultrasonic tomography (UT) is considered to be a promising method for temperature field visualization. The ultrasonic time-of-flight (TOF) measurement and the reconstruction algorithm are crucial for practical applications of the UT measurement. In this paper, a dual-threshold measurement method is proposed to ensure a high-quality TOF measurement. In view of the inaccurate nature of the reconstruction model and TOF data, a new reconstruction method that integrates the advantages of the Tikhonov regularization method and the least squares support vector machine (LSSVM) is proposed to improve the reconstruction quality. The experimental results were compared against thermocouple measurements and the results show that the temperature distribution can be reconstructed with the error of 1.3%, which validates the feasibility and effectiveness of the proposed Tikhonov-LSSVM reconstruction algorithm.     

渗金属气压对光电高温计测温精度影响的实验研究

为准确控制双辉等离子渗金属工件的温度,借助自制的一套热电偶测温实验装置,对光电高温计测温进行了比对实验,探讨了气压对光电高温计测温精度的影响。实验结果表明:在双辉等离子渗金属过程中,对同一工件温度,随工作气压的升高,光电高温计所用的ε值也增大。工作气压每增高5～10Pa,将ε值提高0 1,这时光电高温计的温度测量误差会小于±3℃。     

Pyrometric temperature measurement of ceramic thermal shock samples

The determination of critical failure parameters during thermal shock requires a time and space resolved temperature measurement of the sample. High frequency pyrometry is a suitable technique for such a measurement task, which usually requires the knowledge of the optical properties of the investigated material. Another challenge is the infrared transparency of materials to be checked in the wavelength range of the pyrometer. The thermal shock disks are very thin, due to the need of homogeneous temperature distribution and to maintain a two-dimensional problem. To allow a pyrometric temperature measurement a universal calibration method for high frequency infrared cameras has been developed. Pyrometry in various media was demanded, as well as the estimation of optical properties (reflection, transmittance and emission) for the selected ceramics to be tested.     

加权整体最小二乘法在光学自准直法测量挠曲角中的应用

建立了基于光学自准直法的测量系统,利用该系统提取转台的十字丝坐标,完成了对三维物体的挠曲角测量.首先,采用Sobel提取算子对CCD拍摄到的十字丝图像进行边缘检测.然后,采用了自适应的阈值分割进行直线提取;由于转台上有其它划痕存在,采用局部最小二乘进行十字丝的提取.最后,采用加权整体最小二乘法进行十字丝两条线的直线拟合,联立两方程,得出交点坐标值.结果表明,此方法获取的两直线斜率之积的精度在±1％以内,非常接近十字丝斜率之积的真值(理论真值为-1).使用徕卡经纬仪(精度为0.5″)的角度值作为真值进行精度标定,测得a的精度为3.59″,β的为3.76″,完全满足系统挠曲角测量的精度要求.     

航空发动机全流程参数试验中温度和压力测量综述

航空发动机全流程参数测量是发动机研制阶段的重要环节,是全面了解发动机性能的唯一手段。国内外各大发动机研究机构和工厂对此都非常重视并相当保密。对国内外航空发动机全流程参数测量发展状况进行了介绍,主要对试验中发动机温度和压力的测量技术进行了归纳和分析。     

Application of Least Squares-Support Vector Machine in system-level temperature compensation of ring laser gyroscope

The bias of Ring Laser Gyroscope (RLG) exhibits a non-ignorable characteristic of drift when its temperature changes, which is an important factor of reducing the navigation precision in inertial navigation systems. The limitations of least-squares fitting and neural network are pointed out and a new scheme of system-level temperature compensation of RLG bias based on Least Squares-Support Vector Machine (LS-SVM) is proposed. Temperature experiment of RLG bias is designed and carried out to validate the effectiveness of the proposed method. The traditional modeling method of least-squares fitting is also investigated to provide a comparison with the LS-SVM based method. Allan variance is used to analyze the error terms of RLG before and after compensation. The results show that: the bias instability of RLG output after it has been compensated by LS-SVM model is 1.32 × 10⁻³ °/h, which has decreased 8.57 × 10⁻³ °/h from that before compensation. It indicates that this method has reduced the influence of temperature variation on the RLG bias effectively and improved the gyro’s accuracy.     

电阻应变片在侧面碰撞中车门开启过程监控的应用研究

在侧面碰撞试验中,车辆门锁系统的运动状态因监控位置特殊,目前只能通过高速摄像观察、加速度传感器曲线以及试验后变形结果判断,无法定量分析门锁开启原因。为解决上述问题,对电阻应变片传感器在门锁开启监控上的应用进行研究,利用电阻应变片传感器采集及安装便利性,将应变片与门锁机构运动结合,并运用最小二乘法线性拟合得到了门锁锁体摆臂在水平线上的相对运动位移。试验结果表明,利用电阻应变片在试验过程中能有效监控门锁开启最大运动位移及相对应时刻,可为车辆门锁系统问题研究提供参考。     

空间低温辐射计中的精密电压测量系统

为了基于测温电阻实现空间低温辐射计的腔温测量,研究了系统的电子学测量精度和测量稳定度。结合实际电子学需求,进行方案设计和器件选型,提出了一种新型的基于超低噪基准源LTZ1000ACH,四线制柱状锗电阻GR1400-AA和24位模数转换器LTC2400的对偶相消式精密电压测量系统。对于整个链路信噪比进行了逐级理论计算和分析,并通过电路仿真软件TINA-TI对系统幅频特性和温度响应特性进行了仿真分析,最后在77K液氮环境下对该系统进行了测温精度和长期稳定性测试。实验结果表明:锗电阻实际采样电压值在100μV内波动,长期测量稳定度达到1×10-5;在77K液氮环境下,系统测温精度达到4mK,长期稳定性达到1×10-5。得到的结果基本满足空间低温辐射计电子学部分的设计指标要求。     

Modelling of surface temperature measurement errors in vertical natural convection cooled channels

This paper describes a methodology and numerical procedure for calculation of surface temperature measurement errors in buoyant channel flow applied to the case of surface-mounted thermocouples. Heat transfer calculations within the channel are based on initial measurement information and performed via a marching numerical procedure. The results of these calculations are in turn utilized for the determination of surface measurement errors modelled with emphasis on the thermocouple-induced local heat sink and convective stray losses. The influence of measurement location and channel width on the surface measurement error is numerically investigated for a group of air-cooled channels with results presented in graphical form.     

基于虚拟仪器的串口轮询在温度测试中的应用

为了采集多个AI系列温控仪表的温度信号,该文介绍了Lab Windows/CVI的串口轮询设计方案、AIBUS通信协议、系统硬件连接以及软件功能实现,设计了一种基于AIBUS通信协议和虚拟仪器Lab Windows/CVI的温度测试系统。该系统组态简单,可靠性好,在实际应用中取得了较好的测试效果。     

红外热像仪外场测温的大气透过率二次标定

为了实现测温红外热像仪的外场精确测温,研究了大气透过率的二次标定。建立了红外热像仪的外场远距离测温标定模型,采用一个标准面源黑体和红外热像仪对大气透过率进行了二次标定。首先,用标准面源黑体的设置温度标定大气透过率的二次修正系数;然后,在已知目标感兴趣区域发射率的情况下,用二次修正系数对未知辐射源测量值进行修正,实现未知辐射源目标辐射温度的准确测量。实验显示,随黑体设置温度从50℃不断升高(二次大气透过率近似为1),大气二次透过率修正系数在50～100℃内迅速下降,在100～200℃内下降趋势减缓,逐渐接近于约为0.7的常数。实验结果为测温红外热像仪外场精确测温提供了保证。