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This work presents the use of limited experimental measurements to develop a set of calibrated Simulation parameters that can then be used for reliable simulation of subsea pipeline inspections. The modelling software aRTist is used as the simulation tool, and the calibration is through comparison with experimental images of a well characterised sample in a water tank. Image Quality parameters such as signal-to-noise ratio, contrast and basic spatial resolution are compared with the aim of matching simulated values to experimental results. Currently the model is partially calibrated, with signal-to-noise ratio successfully matched while differences are still found in contrast-to-noise ratio comparisons. This means that measurements depending on absolute intensity are not accurate enough in the simulation at this stage. However, the simulation is found to be accurate for wall thickness measurements in tangential images, which are not based on absolute intensity, with simulated and experimental cases producing similar results.
Accurate and reliable detection of subsea Pipeline corrosion is required in order to verify the integrity of the pipeline. A laboratory trial was conducted with a representative pipe sample. The accurate measurement of the wall thickness and corrosion was performed with high energy X-rays and a digital detector array. A 7.5 MV betatron was used to penetrate a stepped pipe and a welded test pipe of 3 m length and 327 mm outer diameter, with different artificial corrosion areas in the 24 mm thick steel wall. The radiographs were taken with a 40 x 40 cm² digital detector array, which was not large enough to cover the complete pipe diameter after magnification. A C-arm based geometry was tested to evaluate the potential for automated inspection in field. The primary goal was the accurate measurement of wall thickness conforming to the standard. The same geometry was used to explore the ability of a C-arm based scanner in asymmetric mode for computed tomography (CT) measurement, taking projections covering only two thirds of the pipe diameter. The technique was optimized with the modelling Software aRTist. A full volume of the pipe was reconstructed and the CT data set was used for reverse engineering, providing a CAD file for further aRTist simulations to explore the technique for subsea inspections.
In the context of the German aviation security research and development project SILUFRA (secure air freight transport chains), BAM has developed a high-resolution and high-energy X-ray imaging technology for the reliable detection of dangerous and illicit materials in densely packed air freight containers. In the developed technology, a novel combination of high-energy (2-7.5 MeV) X-ray betatron as the radiation source and a high-resolution digital detector array (DDA) for the X-ray imaging was utilized to improve the probability of detecting contraband and explosive materials by enhancing the spatial and contrast resolution in the digital X-ray image. In addition, flexible rotations of the high-energy X-ray source and the digital detector array can lead to clarify the suspicious region of interest (ROI) in air freight containers efficiently. Thus, reduces the false alarm rates and the need for expensive manual inspections of the whole container load. In order to evaluate the detection efficiency, we carried out the experimental investigations on a real air freight container loaded with typical cargo materials such as heavy automobile components and electronic products as well as mock-up dangerous and contraband materials. Furthermore, the material discrimination in the radiographic images was evaluated based on the dual high-energy X-ray imaging method. Finally, important applications of the proposed imaging technology to the air cargo security are discussed