工业射线照相的发展史

概述射线照相用于工业无损检测的早期历史，回顾了近20a(年)来工业射线照相的发展。指出胶片法射线照相仍然是当前工业射线无损检测的主流。     

Real-time radiography at the NECTAR facility

A feasibility study has shown that real-time radiography using fission neutrons is possible at the NECTAR facility, when using an improved detection system for fast variations (Bücherl et al., 2009 [1]).Continuing this study, real-time measurements of slowly varying processes like the water uptake in medium sized trunks (diameter about 12 cm) and of slow periodic processes (e.g. a slowly rotating iron disk) are investigated successfully using the existing detection system.     

数字射线检测技术专题(六)——等价性问题讨论

从成像过程基本理论,给出了等价性问题概念,具体讨论了等价性指标、等价性级别问题,给出了等价性范围讨论的思路、方法,并以矩形函数近似扩散函数为例,说明了讨论等价性厚度范围的过程。     

Implementation of diffraction-enhanced imaging experiments: at the NSLS and APS

Diffraction-enhanced imaging is a recently developed X-ray imaging technique that has demonstrated enhanced contrast for dense, highly absorbing materials of interest in materials science and medicine. The implementation of this technique in experiments at the National Synchrotron Light Source and at the Advanced Photon Source is described in detail.     

Neutron imaging studies of metal-hydride storage beds

Neutron radiography and tomography were used to study the transient and steady-state distributions, respectively, of hydrogen within a prototypical, LaNi_4.78Sn_0.22-based hydrogen-storage bed during and after various absorption and desorption steps. It was shown that using deuterium instead of hydrogen enabled the imaging of thicker beds. These measurements serve to demonstrate the unique utility of neutron imaging as an important diagnostic tool for in situ, real-time characterization of hydrogen-concentration profiles in practical hydrogen-storage systems.     

数字射线检测技术专题(四)——数字射线图像基本理论

介绍了数字图像概念、图像数字化基本理论和射线数字图像质量的基本理论。     

Three-Dimensional Digital Representation of Granular Material Microstructure from X-Ray Tomography Imaging

This paper presents the use of x-ray tomography imaging to reconstruct a three-dimensional (3D) digital representation of individual particles in a granular system. The granular system is represented by the mass center coordinates and the morphology representation of each particle. An automated procedure using pattern recognition to identify related particle cross sections in adjacent serial images was developed. Procedures to calculate quantities needed for subsequent simulation of particle behavior including the volume and the momentum of inertia of each particle are also presented. The developments described in the paper enable modeling and simulation of the behavior, and experimental observations of the particle kinematics of real microstructures of granular materials in a true 3D platform.     

The detection and sizing of flaws in components from the hot-end of gas turbines using phase-contrast radiography with neutrons: a feasibility study

In this paper we present a feasibility study of the use of phase contrast radiography in the examination of components from the hot-section of gas turbine engines. These components are usually made from dense materials (nickel or cobalt based superalloys) and, consequently, radiographic examination requires either high energy X-rays (above 60 keV) or neutrons. The relative merits of employing X-rays and neutrons for phase contrast radiography are compared. It is shown that, for similar penetration, neutrons offer better sensitivity and that it should be possible to detect even micron-wide cracks orientated perpendicular to the incident rays. Simulation shows that, for cracks parallel to the incident rays, crack growth in increments of microns can be resolved by monitoring the development of the Fresnel diffraction pattern. Some preliminary experimental results are also presented that demonstrate an improvement over conventional neutron radiography.     

Toward a Physical Damage Variable for Concrete

Continuum damage mechanics models, while elegant and useful, suffer from what are typically highly idealized relationships between model and material. In this technical note, using three-dimensional (3D) measurements of internal cracking, direct, albeit simple relationships were made between the quantity of cracking and a corresponding scalar damage variable. Geometric properties of internal cracks were measured through 3D image analysis of in situ microtomographic scans of small concrete specimens subject to compression. A scalar damage variable was determined from the changes in stiffness measured in successive loading cycles. Results showed a nearly linear relationship between the damage variable and the volume of new cracks formed. In contrast, results showed a nonlinear relationship between the damage variable and the crack surface area. Such relationships can potentially lead to a more physical basis for continuum damage formulations.     

超声衍射传播时间法与射线照相法对缺陷检出能力的比较

介绍国外焊缝用超声衍射传播时间法(TOFD)与射线照相法在缺陷检出能力和定量精度方面的比较,最后得出,锅炉、压力容器焊缝(板厚>12.7mm)可用超声TOFD法取代RT检测的结论。