Two-dimensional radiographic imaging analysis

Two-dimensional imaging properties of locally isotropic and isoplanatic point spread functions are described in a general radiographic context. In particular, the radiographic response to a two-dimensional wedge-shaped object is shown to possess several properties which enable the identification of the wedge corner on the image, thereby alleviating the need for image enhancement techniques. Extensions to the location of flat-edged boundaries are also discussed. The potential dimensioning application of this analysis lies in the precise and objective location of points of interest on radiographs of more complex two-dimensional objects.     

Water Evolution in Direct Methanol Fuel Cell Cathodes Studied by Synchrotron X‐Ray Radiography

Water evolution, distribution, and removal in the cathodes of a running direct methanol fuel cell were investigated by means of synchrotron X‐ray radiography. Radiographs with a spatial resolution of around 5 μm were taken every 5 s. Special cell designs allowing for through‐plane and in‐plane viewing were developed, featuring two mirror‐symmetrical flow field structures consisting of one channel with the through‐plane design. Evolution and discharge of water droplets and the occurrence of water accumulations in selected regions of the channels were investigated. These measurements revealed a nonuniform distribution of water in the channels. Both irregular and periodic formation of water droplets were observed. In‐plane measurements revealed, that the droplets evolve between adjacent carbon fiber bundles of the gas diffusion layer. The water distribution within the channel cross‐section fits very well to the pressure difference between cathode channel inlet and outlet. The quick discharge of water droplets causes sudden decreases of the pressure difference up to 4.5 mbar.     

Retinex可变框架在X射线图像增强中的应用

为了改善X射线成像对比度低、背景噪声明显、被测工件细节不易显示等缺点,应用改进的Retinex可变框架模型增强算法,对X射线图像进行图像增强,提高了原图像的对比度和像质,达到了细节区域的最佳视觉效果。理论分析和试验结果表明,该算法与同态滤波、直方图均衡化等算法相比,有效地增强了对比度、抑制了背景噪声,图像所达到的指标比前两种算法要高。     

小径管自动X射线实时数字成像检测系统设计

比较和分析了各种小径管对接焊缝X射线实时成像技术,开发出一种性价比极高的自动X射线实时数字成像检测方法和设备。实际应用的结果表明,系统具有检测速度快、灵敏度和分辨率高的特点,成像质量优于JB 4730—2005标准中规定的AB级。     

Visualising Liquid Water in PEM Fuel Cells Using Neutron Imaging

In this article, we review the neutron imaging techniques that have been used to visualise liquid water in PEM fuel cells. A list of the various facilities engaged in this research is provided and the published literature in this field reviewed. Neutron imaging has been successfully used to visualise water dynamics in the flow channels of operating fuel cells. This technique has also been used to understand water removal mechanisms and the importance of membrane hydration and GDL flooding to optimal fuel cell performance. More recently this technique has been applied to imaging the water in fuel cell cross‐sections in order to quantify the water contents in the different components of an operating fuel cell. Finally, this technique has also been utilised to examine ice formation during sub‐zero operation of single fuel cells. With ongoing improvements in spatial and temporal resolution, neutron imaging can be expected to play a greater role in any fuel cell development related to water transport.     

成像板（IP）的使用和保养方法

计算机射线照相（CR）已在国内广泛推广,其成像过程是先把射线影像信息捕俘并储存在涂有氟氯化钡的成像板（IP）上。IP板通过扫描装置发出的激光,经计算机系统处理形成数字化图像,IP板在CR系统中起了传感器、存储器和发光器的作用,因此又称储存发光器（Storage Phosphor）,是整个CR系统的关键部件,本文扼要介绍其使用注意事项。     

^60Co集装箱检测系统中的图像处理

本文分析了＾６０Ｃｏ集装箱检测的特点,提出了集装箱图像的几种特殊处理方法。设计了各种常规的二维数字图像处理算法,包括灰度增强,伪彩色增强,空间滤波,边缘增强,几何处理等。提出了在微机Ｗｉｎｄｏｗｓ９５或Ｗｉｎｔ ＮＴ环境下实现上述处理的方法。分析了在微机环境下提高图像处理速度的几种方法,达到了很好的效果。     

射线照相噪声的理论模式与实验验证——国外射线检测动态

在射线照相影像质量的三要素中，影像噪声（颗粒度）是先决性的。介绍射线底片上噪声的理论处理模式，并对工业上常用的Agfa D4和D7胶片，就计算求出的相关于底片黑度的噪声量值与实验结果作了比较，两者数值颇为一致。     

Quantification of flexural fatigue life and 3D damage in carbon fibre reinforced polymer laminates

Carbon fibre reinforced polymer (CFRP) laminated composites have become attractive in the application of wind turbine blade structures. The cyclic load in the blades necessitates the investigation on the flexural fatigue behaviour of CFRP laminates. In this study, the flexural fatigue life of the [+45/−45/0]_2s CFRP laminates was determined and then analysed statistically. X-ray microtomography was conducted to quantitatively characterise the 3D fatigue damage. It was found that the fatigue life data can be well represented by the two-parameter Weibull distribution; the life can be reliably predicted as a function of applied deflections by the combined Weibull and Sigmodal models. The delamination at the interfaces in the 1st ply group is the major failure mode for the flexural fatigue damage in the CFRP laminate. The calculated delamination area is larger at the interfaces adjacent to the 0 ply. The delamination propagation mechanism is primarily matrix/fibre debonding and secondarily matrix cracking.     

Role of carbon nanotubes in the ballistic properties of boron carbide/carbon nanotube/ultrahigh molecular weight polyethylene composite armor

Composite armor panels with boron carbide ceramic as striking face, backed with carbon nanotube-ultra high molecular weight polyethylene (CNT-UHMWPE), have been fabricated as lightweight body armors. The armor panels were tested against actual ammunitions through self-loading rifle (SLR) and AK-47. Slip lines were observed in boron carbide with high energy bullets. CNT-UHMWPE composite backing resulted in a low back face signature (BFS) due to the formation of a strong bond between CNT and UHMWPE and high energy dissipation through this composite. The role of CNT in the ballistic protection of this composite armor has been explained with the help of necessary characterization by electron microscopy, X-ray radiography, Fourier transformed infrared spectroscopy and differential scanning calorimetry.