大型集装箱检测系统中的图像数字处理性能分析

由于物体对射线的吸收与物体密度成指数关系。大型集装箱检测系统利用这一物理原理，不经过开箱即可检查其中的物品。通过图像重建和处理，就能得到整个物体的透射图像。本文给出在工作站上实现辐射图像处理的具体方法及软件编程。     

Filtering algorithm for dotted interferences

An algorithm has been developed to remove reliably dotted interferences impairing the perceptibility of objects within a radiographic image. This particularly is a major challenge encountered with neutron radiographs collected at the NECTAR facility, Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II): the resulting images are dominated by features resembling a snow flurry. These artefacts are caused by scattered neutrons, gamma radiation, cosmic radiation, etc. all hitting the detector CCD directly in spite of a sophisticated shielding. This makes such images rather useless for further direct evaluations.One approach to resolve this problem of these random effects would be to collect a vast number of single images, to combine them appropriately and to process them with common image filtering procedures. However, it has been shown that, e.g. median filtering, depending on the kernel size in the plane and/or the number of single shots to be combined, is either insufficient or tends to blur sharp lined structures. This inevitably makes a visually controlled processing image by image unavoidable. Particularly in tomographic studies, it would be by far too tedious to treat each single projection by this way. Alternatively, it would be not only more comfortable but also in many cases the only reasonable approach to filter a stack of images in a batch procedure to get rid of the disturbing interferences.The algorithm presented here meets all these requirements. It reliably frees the images from the snowy pattern described above without the loss of fine structures and without a general blurring of the image. It consists of an iterative, within a batch procedure parameter free filtering algorithm aiming to eliminate the often complex interfering artefacts while leaving the original information untouched as far as possible.     

In situ observation of the capillary infiltration of molten silicon in a SiC/SiC composite by X-ray radiography

Capillary infiltration is an innovative fabrication method for metal and ceramic-matrix composites. SiC/SiC composites can be infiltrated by molten silicon to decrease residual porosity. Physical and chemical mechanisms involved during Liquid Silicon Infiltration (LSI) are complex to analyse. An in situ observation setup for capillary infiltration of molten silicon has been designed for synchrotron observations. The setup reproduces the extreme high temperature and high vacuum conditions used in the LSI process. It is also designed for X-ray observations in synchrotron beamlines and tomography stages. Sets of 2D X-ray absorption radiographs were acquired at high frequency during the LSI process. The study outlines the capillary infiltration mechanisms of molten silicon inside SiC/SiC composites. It proves that full saturation of the composite is not directly achieved after the rise of molten silicon. It is a two step mechanism. First, the infiltration occurs inside the intra granular porosity of the SiC powder matrix. Then, larger scale porosities such as cracks are filled. These phenomena have been discussed previously in the literature but never observed in situ.     

In Situ Investigation of Two-Phase Flow Patterns in Flow Fields of PEFC’s Using Neutron Radiography

A novel in situ method for the investigation of the two-phase flow patterns occurring in the flow fields of polymer electrolyte fuel cells (PEFC’s) has been developed. In these experiments, the gas / liquid two-phase flow in hydrogen fuel cells as well as in direct methanol fuel cells (DMFC’s) has been studied. Unique results and the promising use of neutron radiography for PEFC research are shown. Its current limitations but also future developments and opportunities are discussed.     

Comparison of plain radiographs and magnetic resonance images in the evaluation of periosteal reaction and osteoid matrix in osteosarcomas

To determine the relationship and the degree of agreement between radiographs and MR images for the existence of osteoid matrix and periosteal reactions in the initial diagnosis of osteosarcomas. the plain radiographs and MR studies of 54 patients with proven osteosarcoma were retrospectively evaluated. In each tumor the visualization and type of osseous matrix, periosteal reaction and Codman angle were recorded independently for both techniques and by consensus between two radiologists. In 37 tumors agreement existed regarding osteoid matrix and in 31 cases regarding periosteal reactions. The Kappa statistic showed a significant relationship between both tests (0.49 and 0.44, respectively). Both techniques were also not statistically different in the proportion of findings with the McNemar test. Therefore, the ability of MR images seems important in reporting the MR features of bone tumors. Identification of osteoid mineralization and periosteal reaction can also be used with MR in the diagnosis of osteosarcoma.     

X射线管道爬行器的研制

以苏丹输油管道工程无损检测为实例,介绍三用型Ｘ射线管道爬行器的基本原理、应用效果及其具体的研制过程,包括硬件和软件设计过程中应该考虑的一些关键问题,并将辐射场反馈、内定时等新方法应用于管道爬行器,通过大量的实践检验和技术数据对比,证明此爬行器具有经济、高效的特点。     

3D Shape Characterization and Image-Based DEM Simulation of the Lunar Soil Simulant FJS-1

This paper describes a procedure used to characterize the three-dimensional (3D) grain shape of lunar soil and undertake simulations of lunar soil by image-based discrete element method (DEM). Given that detailed 3D grain-shape information is unavailable for real lunar soil, a simulant material, FJS-1, is used in this study. We use the high-resolution micro X-ray CT system at SPring-8, a synchrotron radiation facility in Japan, to visualize precise 3D images of the granular assembly of FJS-1. A newly developed image-analysis procedure is then applied to identify individual grains. Using the obtained grain-shape data, a sufficient number of FJS-1 grains are directly modeled for DEM simulation using an efficient modeling scheme. A series of particle flow simulations are then performed with the modeled grains. The resulting slope angles are in good agreement with experimental results. We discuss the effect on the slope angle of grain parameters such as contact stiffness, restitution coefficient, and interparticle friction.     

基于光频转换器的密度计设计

为提高测量精度和范围,简化仪器结构,提出采用集成光频转换芯片TSL230直接对光信号进行测量,将高、低频率分开采样,输出频率经计数、分频后送于单片机,采用计数法和测周期法进行数据处理,同时对测量数据进行了校正。实验证明此方案减小了分布参数及其它外界参数的影响,稳定了测量结果,提高了测量精度,扩大了测量范围,有较好的推广价值。     

Visualization of the water distribution in perforated gas diffusion layers by means of synchrotron X-ray radiography

Perforated gas diffusion layers (GDLs) of polymer electrolyte membrane fuel cells (PEMFCs) were investigated by means of in-situ synchrotron X-ray radiography during operation. We found a strong influence of perforations on the water distribution and transport in the investigated Toray TGP-H-090 GDL. The water occurs mainly around the perforations, while the holes themselves show varying water distributions. Some remain dry, while most of them fill up with liquid water after a certain period or might serve as drainage volume for effective water transport.