用于工业CT图像三维重建的边缘信息提取算法研究

本文探讨了CT图像边缘提取的常规方法,引入了启发式搜索算法用于工业CT图像的边缘信息提取;通过这种方法可以得到连接闭合的单象素边缘图像,为将来的序列CT图像三维重建提供了原始数据.最后针对箱包CT图像进行了算法验证,实验表明在图像存在噪声和伪影的情况下,算法仍能检测出满足三维重建需求的边缘信息.     

工业CT图像的二维几何测量方法研究

为实现对物体内部结构尺寸的无损测量,提出一种基于阈值化边缘提取的工业CT图像几何尺寸的自动测量方法。首先对CT图像进行预处理,然后采用最佳阈值分割方法进行边缘提取,在此基础上实现了对工件的CT图像的几何尺寸的自动测量。实验结果表明:对图像的几何测量达到了一定的精度,基本上满足了可重复性和精确度的要求。同时这种方法对于有伪影的图像,可以有效地减少伪影的影响。     

基于结构先验的变电压CT成像

为获得更高质量的CT重建图像,建立了基于结构先验的变电压CT成像方法。该方法对同一像素点在不同电压下满足最佳灰度带的有效投影数据进行叠加迭代重建,得到递变电压的重建结果,通过设定阈值,将低电压下投影数据的重建结果分为两个部分,将边缘的结构部分先验地运用到高电压下投影数据的重建结果里,以此弥补变电压重建图像过程中的信息缺失。仿真实验表明:该方法能够获得完整的工件信息,重建图像质量高,像素值也更加稳定。     

矩形窄流道内汽泡行为的图像自动识别与分析

针对矩形窄流道内沸腾流动时产生的汽泡动力学行为，采用高速摄影仪进行汽泡行为捕获，再利用图像处理技术识别汽泡，最后提取出特征参量进行分析。通过采用改进图像处理法解决了光斑带来的二值化图像中部分汽泡边缘不封闭的问题，并达到了较好的汽-液分割效果；然后通过自动处理提取出图像中的汽泡投影面积比，并采用人工识别的汽泡投影面积比进行验证，两者相差在10%以内；最后根据接触角建立了汽泡体积计算模型，得出了汽泡生长过程中空泡份额变化趋势。      

CT图像重建方法在半影成像中的应用

CT图像重建方法和半影成像是两种传统的辐射图像诊断方式。将CT图像重建方法应用到半影图像数据处理中,探索出一种新的半影图像处理方法。在新的半影编码孔图像数据处理中,首次应用了与图像诊断系统点扩散函数无关的编码孔图像处理方法,解决了传统编码孔图像处理中由于图像诊断系统点扩散函数不确定带来的技术难题。在理论研究的基础上进行了半影模拟成像及图像重建,获得了理想的研究结果。     

基于引力模型的固体发动机CT图像边缘检测

为对固体发动机的CT图像进行更有效的边缘检测,提出一种基于引力模型的边缘检测算子。利用新的边缘检测算子得到固体发动机边缘图像,通过与常用边缘算子检测结果的比较,得出新算子对边缘检测的优越性;通过不同尺寸新算子的边缘检测结果的比较,还得出成像质量高的CT图像选择小尺寸算子进行边缘检测、成像质量低的CT图像选择大尺寸算子进行边缘检测的结论。     

X射线分层成像中灰度重建的研究

利用边缘提取和立体匹配技术可对Ｘ－射线立体透视图像进行分层成像， 但分层后得到的物体图像仅仅是边缘图像。研究了一种利用原始的灰度图像对分层后的边缘图像进行灰度重建的方法。使得每一层的图像有接近实际的灰度图像。     

X—射线分层成像中灰度重建的研究

利用边缘提取和立体匹配技术可以对X-射线立体透视图像进行分层成像，但分层后得到的物体图像仅仅是边缘图像，研究了一种利用原始的灰度图像对分层后的边缘图像进行灰度重建的方法，使得每一层的图像的接近实际的灰度图像。     

用旋转极坐标法在少投影条件下重建钢管截面图像

钢管的在线检测和控制是提高其质量的重要环节,也是目前亟待解决的难题.射线CT成像技术作为一种高效的图像检测手段,特别适合对钢管截面的尺寸参数进行检测和控制.本文利用旋转极坐标法在少投影条件下获得钢管截面的重建图像,该方法不仅减少了投影数目,缩短了数据采集时间,且加快了算法速度,节约了图像重建时间,大大减少钢管检测的时间.模拟试验和实际试验的结果均表明,旋转极坐标法的重建效果和重建时间基本可满足目前钢管在线检测和控制的要求,具有一定的理论意义和应用前景.     

大型工业CT中X射线硬化校正的一种方案

介绍了大型工业CT的一种多色X射线硬化校正方法。该方法利用一个标准函数将多色投影值转化为单色投影值。定义了一些参数来证明该方法适用于大型工业CT的硬化校正,并对参数进行了优化。通过模拟实验,这种校正方法在不需要先验知识,使用单色重建算法的前提下,仍能大大减小CT重建图像的硬化伪像。     

一种新的边界检测方法及其在核医学图象定量分析中的应用

本文对过去若干种边界检测方法的实验对比基础上,并结合TL-201心肌灌注图象的处理,提出一种新的边界检测方法,即“改进的RS方法”。实验证明,该方法对噪声和干扰具有很高的抑制作用,并适合其它应用领域。迭代法计算边界重心,以及快速傅里叶变换边界优化,使该方法更为客观、可靠。由此方法所得到的边界,可满意地用于核医学图象的定量分析。     

一个启发式的图像边缘检测方法

用启发式图像边缘检测的方法对图像做了实验，并与经典边缘检测方法进行了比较。结果表明，此方法比经典法在检测质量上有较大的改善，能准确有效地将图像目标的边缘从背景中提取出来．     

Improved plasma position detection method in EAST Tokamak using fast CCD camera

To control the steady-state operation of Tokamak plasma, it is crucial to accurately obtain its shape and position. This paper presents a method for use in rapidly detecting plasma configuration during discharge of the Experimental Advanced Superconducting Tokamak device. First, a visible/infrared integrated endoscopy diagnostic system with a large field of view is introduced,and the PCO.edge5.5 camera in this system is used to acquire a plasma discharge image. Based on the analysis of various traditional edge detection algorithms, an improved wavelet edge detection algorithm is then introduced to identify the edge of the plasma. In this method, the local maximum of the modulus of wavelet transform is searched along four gradient directions, and the adaptive threshold is adopted. Finally, the detected boundary is fitted using the least square iterative method to accurately obtain the position of the plasma. Experimental results obtained using the EAST device show that the method presented in this paper can realize expected goals and produce ideal effects;this method thus has significant potential for application in further feedback control of plasma.     

Latest developments in image processing for the next generation of devices with a view on DEMO

In magnetic confinement fusion devices the use of cameras, both visible and infrared, has increased very significantly in the last years. The large amount of data (in the range of tens of Gbytes per shot) and the difficulty of the analysis tasks (ambiguity, ill posed problems, etc.), require new solutions. The technology of Cellular Nonlinear Networks (CNNs) has been successfully applied to various tasks, from the real time hot spot detection to the automatic identification of instabilities. The accuracy obtained is comparable to the one of more traditional serial algorithms but the CCNs guarantee deterministic computational times independently from the image contents. Moreover the latest developments have allowed obtaining these results also in the case of space variant image analysis, without compromising the computational speed (of the order of ten thousand frames per second). The method of the optical flow permits to derive information about the speed of the objects moving in the frames of a single camera. The results of previous applications have been so successful that the approach has been extended to videos in compressed format (MPEG) to reduce the computational time to less than 7 ms per frame, preserving the accuracy of the results. Since in the next generation of devices, also the edge will emit Soft X-rays (SXR), new technologies are being developed to perform imaging over this region of the spectrum for a global view of the entire plasma column.     

~(60)Co货运列车检测系统数字减影检测技术研究

为克服传统~(60)Co货运列车检测模式中检查员易疲劳、查验效率低的不足,本文提出了一种实用的列车图像检测方法,该方法以一套标准图像库为基础,通过对车厢图像与标准图像的配准和数字减影处理,凸显出二者的差异,然后根据差异程度进行风险分级,从而使图像检查员有针对性地进行检查,提高了系统的检查效率。该系统已在中国多处铁路口岸装备运行。     

EAST等离子体图像采集与位置识别技术

本工作采用快速CCD相机采集并保存托卡马克等离子体放电时的图像。根据放电时等离子体图像的位置特点,采用改进的主动轮廓模型算法实时获得等离子体边界位置,并通过最小二乘法对其边界进行拟合,以此获得等离子体的中心位置,为进一步进行等离子体的实时控制提供了基础。该方法已成功应用于EAST装置的放电实验中,并取得了良好的效果。     

A heat transfer analysis of the CCI experiments 1-3

This paper presents an attempt to evaluate the heat transfer rates and gas release rates in the CCI core-concrete interaction experiments 1-3, performed within the OECD MCCI project. A new method for calculating the heat transfer rates has been developed. It is based on calculating integrals of the concrete enthalpies with the help of piecewise exponential interpolation curves. The new method takes into account heat conduction in the concrete. Compared to traditional methods, the new method gives better results during slow concrete ablation, and its time resolution is significantly better. The gas release rates from the concrete were also calculated. A regression analysis was conducted for the heat transfer coefficients and gas release rates. Three correlations for the bubbling-enhanced heat transfer were developed. For the basemat, a single correlation can be used for both siliceous and limestone/common sand (LCS) concrete types. For the sidewall, two different correlations are needed for the two concrete types. With the same superficial gas velocity, the heat transfer rate to siliceous sidewalls is higher than to LCS sidewalls. This suggests that the reason for the different radial ablation rates of the concrete types observed in the tests is not the lower gas content of siliceous concrete.     

Development of an original active thermography method adapted to ITER plasma facing components control

Among all non-destructive examinations (NDE), active infrared thermography is becoming recognised as a technique available today for improving quality control of many materials and structures involved in heat transfer. The infrared thermography allows to characterise the joint between two materials. In order to increase the defect detection limit of the SATIR test bed, several possibilities have been evaluated. The implementation in 2003 of a microbolometer camera and the improving of the thermosignal process allowed to increase considerably the detection sensitivity of the SATIR facility. The quality, the spatial stability of infrared image and the detection of edge defect have been also improved. The coupling on the same test bed of SATIR method with a lock-in thermography will be assessed in this paper. An improvement of the global reliability is expected by data merging produced by the two thermal excitation sources. This new facility SATIR UPGRADE has been designed for the full non-destructive examination of the high heat flux (HHF) components taking into account these main improvements. These systematic acceptance tests obviously need tools for quality control of critical parts.     

一种新的在线称重方法

介绍了一种新的在线称重方法的基本原理:利用图像分析测量物料堆积体积,结合γ射线测量物料堆积密度,然后根据体积和密度计算物料的重量.最后讨论了该方法的初步试验结果.