共查询到20条相似文献,搜索用时 78 毫秒
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分析了尺缩效应的导出过程及其可能引起的误解,阐述了狭义相对论关于不同惯性系对同一物体长度测量的另一种观点,并对两种不同长度测量方式进行了比较. 相似文献
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为了克服传统调制相移法测量频率范围窄、测量准确度低的缺点,提出一种基于调制相移法的单模光纤长度精确测量技术.利用一体化矢量网络分析仪的高速调制信号同步技术及高频信号相位差测量技术,设计并研制了单模光纤长度测量装置.基于矢量网络分析仪自带的VBA插件编写了自动控制及数据处理软件,给出了相位变化量自动处理方法.利用研制的装置分别测量了长度为2km、40km和150km的单模光纤在不同工作波长点的长度值,实验结果表明,2km的光纤长度测量值实验标准偏差优于0.2mm,150km的光纤长度测量值实验标准偏差接近0.01m.该装置可对1 310nm、1 490nm以及1 550nm波长的光纤距离进行精确测量,为光纤长度的高准确度测量提供了一种新的技术途径. 相似文献
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在切边冲孔机长时间生产中,为了减小菲林形变引起的柔性电路板(FPC)冲切位置误差,利用目标冲切完成后的图像信息,测量金手指与冲切边缘间的距离,计算出系统误差并进行误差补偿。结果显示,经过误差补偿后,系统的冲切位置均方根误差在X与Y方向分别减小了41.6%与17.0%,系统的制程能力指数(CPK)达到1.611 8。利用菲林加大了FPC产品的外围尺寸,提高了产品的可利用面积,降低了生产成本。提出的超分辨率快速测量方法不需要对图像进行配准,可以将边缘位置定位误差由0.5个像素降低为0.25个像素。使用的误差补偿方法能够减小长时间生产所引起的冲切位置误差,设计的系统满足FPC的冲切精度要求。 相似文献
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The length of electron beam from a photocathode RF gun is determined by a spectrometer, according to the relative energy spread induced by the bunch length during the acceleration in a linac. For a photocathode RF gun, different laser injected phase and beam charge are studied. The compression is changed for the different laser phases, as from 10° to 30°, and the bunch length is lengthened due to the strong longitudinal space charge force, caused by the increased charge. 相似文献
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The well-known nodal point method has been employed with some modification to measure the focal lengths of divergent lenses. In this modification, a telescope was used to locate precisely the nodal/principal point of the lens under test, and a travelling microscope was employed to locate precisely the focal point of the lens as well as to measure the focal distance. The accuracy of the measurement was found to be ± 0.5%, with the focal length of the order of about 10 cm. 相似文献
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G.G. Wood 《Journal of magnetism and magnetic materials》2010,322(13):1775-1778
The identification of a time and temperature dependent spin glass correlation length, ξ(t,T), has consequences for samples of finite size. Previous experiments on layered samples show a suppression of the freezing temperature with decreasing sample thickness. The correlation length exceeding the finite sample thickness can explain these results. This novel analysis lends further credence to the correlation length paradigm of understanding spin glasses. 相似文献
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RF deflecting cavity can be used for bunch length measurement and is designed to diagnose the beam produced by the photocathode electron gun which was built at Tsinghua University for the Thomson scattering experiment. Detailed discussion and calculation for measuring the 3.5 MeV bunch and another with further acceleration to 50 MeV, which is under development, are presented. A standing-wave deflecting cavity working at 2856 MHz is designed and the power feeding system has been planned. 相似文献
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SHI Jia-Ru CHEN Huai-Bi TANG Chuan-Xiang HUANG Wen-Hui DU Ying-Chao ZHENG Shu-Xin REN Li 《中国物理C(英文版)》2009,33(Z2)
An RF deflecting cavity used for bunch length measurement has been designed and fabricated at Tsinghua University for the Thomson Scattering X-Ray Source.The cavity is a 2856 MHz,π-mode,3-cell standing-wave cavity,to diagnose the 3.5 MeV beam produced by photocathode electron gun.With a larger power source,the same cavity will again be used to measure the accelerated beam with energy of 50 MeV before colliding with the laser pulse.The RF design using MAFIA for both the cavity shape and the power coupler is reviewed,followed by presenting the fabrication procedure and bench measurement results of two cavities. 相似文献