Browsing by Author "Wilson, Alan"

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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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    ItemOpen Access
    Exploring potential causal models for climate-society-conflict interaction
    (Scitepress, 2023-04-22) Guo, Weisi; Sun, Schyler; Wilson, Alan
    Climate change affects human liveability and may increase the likelihood of armed violence. However, the precise repercussions on social cohesion and conflict are difficult to model, and several socio-economic mechanisms exist between local climate changes and conflict, and are often hidden to us. Nonetheless, we offer an exploratory data analysis in this paper at a global scale, on the relationship between diverse climate indicators and conflict. Here we investigate potential basic causal models between climate change and conflict, including the causal direction, causal lag, and causal strength. We use historical climate and extreme environmental event data from the past 50 years across the world to identify geographic region-specific causal indicators. The initial broad findings are: (1) rainfall is a reasonably general indicator of conflict, (2) there are fragile regions which exhibit a strong causal link between extreme climate variations and conflict (predominantly in Africa and South Asia), and 3. there exists a common time lag of the causality between the climate variations and the conflict in many regions, which is worth further study.