Browsing by Author "Yang, Xiuyuan"

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    An automated surface determination approach for computed tomography
    (Elsevier, 2022-06-23) Yang, Xiuyuan; Sun, Wenjuan; Giusca, Claudiu
    Surface determination is a critical image processing step in X-ray Computed Tomography that uses algorithms based on local thresholding methods, such as Canny and Steinbess, to detect the surface of metallic components with intricate designs and complex topographies. In most of the cases, these algorithms require trial-and-error tests to optimise the threshold operation, leading to unreliable and, at times, erroneous inspection results. This paper demonstrates the ability of marker-controlled watershed algorithm to automate the surface determination process and to maintain its robustness in the presence of beam hardening and complex topographies, outperforming the current commercial and non-commercial software implementations.
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    Data supporting "An automated surface determination approach for computed tomography"
    (Cranfield University, 2022-08-31 17:00) Yang, Xiuyuan; Giusca, Claudiu; Sun, Wenjuan
    This dataset contains the reconstructed simulation data, MCW surface point clouds, measurement results used for Fig 14 and Fig 16.
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    Establishment of X-ray computed tomography traceability for additively manufactured surface texture evaluation
    (Elsevier, 2021-12-14) Sun, Wenjuan; Giusca, Claudiu; Lou, Shan; Yang, Xiuyuan; Chen, Xiao; Fry, Tony; Jiang, Xiangqian; Wilson, Alan; Brown, Stephen; Boulter, Hal
    Metal additively-manufactured (AM) parts are increasingly used as safety-critical components in industry. Surface textures of metal AM parts are different to conventionally machined surfaces and can directly influence the functional performance of the parts. However, it is difficult or impossible to access and measure non-line-of-sight AM surfaces by conventional measurement techniques. X-ray computed tomography (XCT) is a promising technique that can measure non-line-of-sight surfaces non-destructively. However, the metrology framework for XCT to evaluate surface texture of AM parts is yet to be fully established, and there is a lack of development in surface texture reference standards that fit the purpose. In this paper, we have established a route to calibrate XCT for AM surface texture evaluation using a prototype three-dimensional roughness standard (3DRS) developed by the National Physical Laboratory that has a range of AM surface texture features and was designed for compatibility between 2D (profile), 2½D (areal), and tomography measuring instruments. A measurement protocol has been established between XCT and the contact stylus system, and uncertainty evaluation of 3DRS surface texture was established.
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    The study of influence factors in x-ray computed tomography using simulation approach.
    (2018-08) Yang, Xiuyuan; Giusca, Claudiu; Sun, Wenjuan
    XCT simulation scanning was used throughout the study because simulation scanning has the flexibility in changing scanning parameters as well as improving the efficiency. The research investigated the effect of voltage, scattering-contamination and multi-sampling on the quality of 2D image projection. For The study tested factors of scattering-contamination, multi-sampling and cone-beam angle on dimensional measurement error with the numerical geometry samples including spheres, cubes, cylinders and tubes. For cylinders and tubes, the measurement of outer diameter leaded more deviation than inner diameter. Scattering contamination had limited influencing (up to 1/35 of the voxel size) to the measurement result but scattering contamination can amplify the operator factor in the geometry determination step. 3X3 multi-sampling detector could optimise the measurement result when measuring the diameter of the cylinder. On the other hand, the effectiveness of the application of multi-sampling is related to the geometry features for measure, and the effect is independent to the scattering-contamination. When measuring circles on the tube, the cone-beam angle had only slight influence (up to 1/131 of voxel size) on the measurement error.
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    Surface determination algorithm for accurate XCT bidirectional length measurements
    (Elsevier, 2023-09-23) Yang, Xiuyuan; Sun, Wenjuan; Giusca, Claudiu
    Surface determination plays an important role in XCT bi-directional length measurement, however, its effect on the measurement results is often overlooked or hidden by other error sources. Most of the published research in dimensional field used the Canny algorithm or the surface determination module in VGStudio. Both of them require input from the operator that can also affect the accuracy of the measurements. Alternatively, the marker-controlled watershed (MCW) algorithm has been proven to avoid the latter issue, however, there is no systematic study that evaluated the surface determination algorithm's effect on the accuracy of bi-directional length measurements. In this study a two-sphere reference sample was measured using an XCT scanner and, with the aid of simulations, the effect of the three surface determination methods on bi-directional length measurements was comprehensively studied. The results show that in the presence of ‘streak’ artefacts, a beam hardening error, if the operator does not set parameters appropriately, Canny and VGStudio implementations lead to either loss of surface or large errors, whereas MCW avoids this issue demonstrating its process automation ability. Nevertheless, with voxel calibration, beam hardening correction and data manipulation, MCW and Canny algorithms enable accurate sphere radius measurements (bi-directional measurements), comparable to the accuracy of an industrial tactile coordinate measuring machine.