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《机械工程与自动化》2017,(5)
为了高精度地测出弧板的厚度,提出了在线测量的方法,并主要分析在线测量中重要的水压闭环控制子系统的控制方案。基于西门子PLC对水压进行控制,通过自适应算法实现水压的恒定,从而实现在线测量。采用水压闭环控制实现了对弧板厚度的在线测量,通过测厚仪实时读取弧板的厚度,精度达到0.01mm。 相似文献
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为实现环状气液两相流界面波液膜厚度的准确测量,基于环状流界面波的理论分析和实验研究,将实时海浪模拟思想引入界面扰动波研究,建立了基于三级海浪函数的界面扰动波模型。设计了一种基于直接测量法的可调节插入深度的波状液膜厚度测量传感器。提出了基于占空比算法的时平均液膜厚度动态校准方法。对测量传感器进行测量不确定度来源分析及评定,提出了系统误差补偿算法。在双闭环可调压中压湿气实验装置上对上述测量传感器进行了实验验证,结果表明:以三级海浪为模型进行研究在任意统计时间与任意插入深度增量条件下,94.44%的实验点的相对测量不确定度在2%以内;基于直接测量法实现液膜厚度复现并使用系统误差补偿算法,提高了测量精度。 相似文献
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为了测量机械设备中的薄油膜厚度分布,对超声测量薄油膜厚度分布的方法进行了理论研究。基于声波在三层介质中传播的相关理论,对中间层油膜厚度远小于油膜中入射声波波长的情况,结合具体边界条件,建立斜入射时超声波在三层介质中传播的反射系数弹簧模型,获得反射系数和油膜刚度的函数关系,进而由刚度获得油膜厚度;分析超声波入射频率、入射角度和油膜厚度对反射系数的影响规律,通过测量油膜中各点的反射系数即可获得相应点的油膜厚度,实现油膜厚度分布的测量。 相似文献
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讨论了采用摄像法测量厚度的原理实现结冰传感器标定的方法。提出了一种测量结冰厚度的方法,通过对摄像头和图像采集卡采集的结冰数字图像进行处理,提取边界来测量结冰层的厚度,进而对结冰传感器的输出进行标定。描述了测量系统中的光学系统和结冰图像的数字处理过程,并且给出了厚度测量的结果。 相似文献
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桥梁偏心和道砟厚度是否符合工程设计需求,是影响铁路桥梁质量和行驶安全的重要性能参数.结合铁路桥梁建设实际,针对桥梁偏心和道砟厚度参数的测量工艺进行研究,分析其具体测量要求及实际现状,介绍铁路桥梁线路偏心和道砟厚度测量工艺实现原理,拟定科学的测量方案,并针对其在铁路桥梁工程的测量的实际应用进行深入探讨. 相似文献
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Pozsgai I 《Ultramicroscopy》2007,107(2-3):191-195
Calibrating on a series of thicknesses of a single element we arrive at a simple method of mass thickness determination for amorphous and polycrystalline films in the transmission electron microscopy (TEM). The conditions to be fulfilled are: acceleration voltage 200 kV or higher and measuring the integrated transmitted electron intensity in a wide range of angles that contains also the Bragg reflections. Under these conditions the electron scattering depends on Z2 as predicted by the Rutherford approximation. There is no need to carry out a calibration for atomic number dependence. For multicomponent films of unknown composition the combination of electron and X-ray intensity measurement results in absolute (non-normalized) concentrations and the value of local mass thickness. Examples of quantitative analysis are presented and an extension to single crystal films is discussed. 相似文献
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利用X射线衍射,是目前国际上对超薄多层膜进行检测常用的方法之一,但只局限于双晶或小角衍射仪。本文利用的方法解决了广角衍射仪在低角区测量时由于样品放置误差所造成的衍射峰偏移和得不到衍射曲线的问题,从而使广角衍射仪得以应用在小角区测量。文中重点对测量曲线进行了分析,准确计算了多层膜的周期和单层膜厚度,并与测量值进行了比较,结果表明利用广角衍射仪测量膜厚是切实可行的。在目前我国X射线波段反射率测量装置还没有完善的条件下,利用X射线衍射仪对超薄膜的检测更显得格外重要。 相似文献
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椭圆弯晶谱仪具有测谱宽度大,能谱分辨力高等特点,并在"神光II"激光惯性约束聚变实验研究中得到了很好的应用。利用X射线衍射仪铜(Cu)靶X射线管作为X射线线光源,选取合适厚度滤片,抑制Cu-Kβ线及韧致辐射,测量了Cu-Kα能点处二氧化硅石英椭圆弯晶的积分衍射效率和摆动曲线半高全宽,并开展了针对上述两个重要参数随晶体弯曲曲率半径改变的测试验证,预估了能谱分辨力。结果表明,椭圆弯晶的积分衍射效率和摆动曲线半高全宽对晶体弯曲半径改变敏感,通过提高晶体弯曲度可增强晶体"镶嵌"效果。该结果可为下一步优化设计多用途性椭圆弯晶谱仪,以及完善X射线光谱定量化测量提供了数据支撑。 相似文献
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We describe a system for vacuum deposition which measures as well as controls substrate temperature, film thickness, and rate of evaporation. By measuring the resonant frequency of a quartz crystal oscillator which has been calibrated for thickness, we produce films of 11 different thicknesses in a single evaporation. The system is then capable of immediately initiating four-probe resistivity measurements on the evaporated films every 90 s, allowing the measurement of rapid structural changes. The system is calculator-based and interfacing is achieved with plug-in compatible instrumentation using the IEEE standard 488-1975 interface bus. 相似文献
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在用铸铁烘缸的检测及评定 总被引:1,自引:0,他引:1
对一台试验烘缸进行强度试验和硬度测试,根据强度与硬度的关联式,基于合乎使用的原则,选取相对硬度RH=0.8。对缸体壁厚测定先经过声速校定再进行壁厚测定,同时发现烘缸法兰、凸缘过渡段有“假”厚度现象,缸体壁厚测定应避开这两个部位。分析了铸铁烘缸超声检测的特点,通过对不同试块、各种探头进行灵敏度检测及试验分析,得出采用小角度纵波双晶探头可检测Φ3mm当量直径的体积形缺陷和采用大角度纵波双晶探头可检测筒体及小尺过渡区2mm深裂纹类面状缺陷.并对2mm深裂纹类面状缺陷进行安全评定。 相似文献
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A quantitative electron beam induced current method is shown, applicable in situ for electron beam current measurement on a semiconductor sample without the need for a Faraday cup. As a validation technique, the measurement of top overlayer thickness in the semiconductor structure was chosen for two reasons. First, the measured thickness is easily verified using the same electron microscope in the secondary electron mode by measuring the layer thickness at the layer edges. Second, the measurement of a layer thickness and its local variations constitute an important issue in semiconductor processing and characterization. The proposed method is used in the planar view of the sample, and also for locations far from the layer edges. Quasi‐three‐dimensional maps of the thickness spatial distribution are presented. 相似文献
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《Ultramicroscopy》1987,21(1):47-61
Three different methods for computing scattering amplitudes in High Resolution Transmission Electron Microscopy (HRTEM) have been investigated as to their ability to include upper Laue layer (ULL) interaction. The conventional first-order multislice method using fast Fourier transform (FFT) and the second-order multislice method (SOM method) are shown to yield calculated intensities of first-order Laue reflections with the use of slice thicknesses smaller than the crystal periodicity along the incident electron beam direction. It is argued that the calculated intensities of ULL reflections approach the correct values in the limiting case of vanishing slice thickness and electron wavelength. The third method, the improved phasegrating method (IPG), does also in principle include ULL effects, but is severely limited as to choice of slice thickness and sampling interval. A practical way to use slice thicknesses less than the crystal periodicity along the incident beam direction is shown for both the conventional FFT method and the second-order multislice method and tested on a spinel structure. It is also shown that the IPG method does not easily allow for aslice thickness different from the crystal periodicity in the beam direction. 相似文献