面向个人剂量计校准的小尺度伽玛参考辐射模拟研究

针对伽玛射线个人剂量计基于标准伽玛参考辐射进行校准时检定效率低、校准工作复杂和需要远程送检的关键技术问题,建构了1 Ci 137Cs放射源小尺度参考辐射场物理模型,采用蒙特卡罗方法,研究了小尺度参考辐射场内的剂量分布、装置结构和待检剂量计变化导致散射射线对剂量场的影响,获得了待检剂量计形状、数量、类型和装置结构产生的散射伽玛射线对小尺度参考辐射量值定度的影响结果。研究结果表明,1 Ci 137Cs可以为小尺度参考辐射辐射场检验点提供1.5 mSv/h的伽玛遂行剂量率,辐照个人剂量计载台直径30 cm束斑上的剂量率相对标准偏差约为0.48%。当载台厚度为20 mm时,散射射线对小尺度参考辐射检验点处剂量率值的影响率为3.27%,高于剂量计尺寸（1.62%）和剂量计数量（0.56%）的影响。     

Classifying land cover based on calibrated full-waveform airborne light detection and ranging data

The capability of the parameters derived from waveform data in discriminating objects is assessed and the effect of the relative calibration of full-waveform data in discriminating land-cover classes is evaluated. Firstly, a non-linear least-squares method with the Levenberg-Marquardt algorithm is used to fit the return waveforms by a Gaussian function. Gaussian amplitude, standard deviation, and energy are extracted. Secondly, a relative calibration method using the range between the sensor and the target based on a radar equation is applied to calibrate amplitude and energy. The change in transmit pulse energy is also considered in this process. A support vector machine classifier is used to distinguish the study area into non-vegetated area （including roads, buildings, and vacant lots）, grassland, needle-leaf forests, and broad- leaf forests. The overall classification accuracy ranges from 79.33% to 87.6%, with the combination of the two groups of the three studied parameters. Calibrated data classification accuracy is improved from 1.20% to 6.44%, thus resulting in better forest type discrimination. The result demonstrates that the parameters extracted from the waveforms can be applied effectively in identifying objects and that relative calibrated data can improve overall classification accuracy.     

提高激光传感器用于现场校准装置精度的研究

阐述了激光传感器在位移传感器现场校准装置中的应用,对激光传感器的测量原理及校准方法进行了分析。结合现场校准的特殊性,分析现场校准过程中的误差来源,提高现场校准的精度。应用2m比长仪对激光传感器进行溯源,研究激光传感器在大长度测量应用中提高精度的方法,采用曲线拟合的方法对测量结果进行补偿。最后应用空气弹簧隔振平台的高度监控系统对溯源后的激光传感器进行验证。实验结果表明,应用激光传感器的位移传感器现场校准装置,其精度可以达到0.1%。     

实测太赫兹频谱线性缩放分析与偏移修正

分析了在太赫兹时域光谱系统的实际测量应用中由延迟线机构倾斜造成实测频谱产生线性缩放的原因;以现有商用化高精度傅里叶变换红外光谱仪的测量结果作为参考,对实测频谱线性缩放进行比对修正,得到了与真实值更接近的结果,证明了该方法的可行性.     

Camera calibration approach using circle-square-combined target

Calibrating a small field camera is a challenging task because the traditional target with visible feature points that fit the limited space is difficult and costly to manufacture.We demonstrate a novel combined target used in camera calibration.The tangent points supplied by one circle located at the center of a square are used as invisible features,and the perspective projection invariance is proved.Both visible and invisible features extracted by the proposed feature extraction algorithm are used to solve the calibration. The target supplies a sufficient number of feature points to satisfy the requirements of calibration within a limited space.Experiments show that the approach can achieve high robustness and considerable accuracy. This approach has potential for computer vision applications particularly in small fields of view.     

基于构建初始测量网络的相机内部参数校准

提出了一种基于构建初始测量网络的相机内部参数校准方法,有效解决了二维平面靶标在深度方向信息的不足以及三维靶标空间的限制等问题。通过对靶标板进行初始成像,按照测量网络的构建原则建立初始测量网络,经过后方交会求解外方位、前方交会求解空间三维靶标点坐标,最后由光束平差优化求解相机内部参数。利用标定后内部参数求解空间点坐标,实验结果表明,采用构建初始测量网的误差平均值为0.0794,优于平面靶标和立体靶标标定的-0.2443和-0.1916。同时校准所用时间也明显小于虚拟立体校准,即该方法具有快速、精确和方便等优点,满足大空间视觉测量中相机内部参数现场校准的要求。     

碳素结构钢的光电发射光谱分析方法

本文研究了火花光源－原子发射光谱法测定碳素结构钢化学成分的最佳条件，根据单道扫描型光谱仪自身的特点，选择预然时间和积分时间，并研究了钢坯及轧制成材化学成份的均匀性。将建立的校准曲线应用于进口及国产标样的测定，获得准确结果，将本方法应用于几种实际样品的测定，结果与国家标准方法吻合，对三个含量级样品的精密度实验中，连续重复精密度RSD≤5.24%；继续重复精密度基本上RSD≤5.78%；再现精密度RSD≤7.82%。     

高温高压声接收换能器的研制和校准

我们研制了一种带毛细孔的能耐150℃和1420atm的高温高压声接收换能器(水听器),并在直径为70mm,高为290mm的圆筒形腔体内用就地互易法在上述高温高压条件下进行了校准.在频带为10Hz—10kHz的频率范围内,接收电压灵敏度为—195±1.5dB(0dB为1V/μPa),水平方向性的不均匀度小于±1.5dB.在常压到1420atm的压力范围内,接收电压灵敏度随压力的变化小于1dB;在150℃时的接收电压灵敏度,较常温下的接收电压灵敏度,只降低3dB.     

PC—Ⅰ型数字式pH检定测量仪原理及校准

介绍了ＰＣ－Ⅰ型数字式ＰＨ检定测量仪的工作原理及校准方法、校准步骤。