I12-JEEP: Joint Engineering, Environmental and Processing
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Open Access
Abstract: X-Ray parallel-beam micro-tomography systems at synchrotron facilities are mainly bespoke designs. Technical problems from a detector system can strongly affect the quality of reconstruction results. Radial lens distortion in the visible light optics causes streak artifacts which get stronger towards the edge of the image. The irregular response of the detector gives rise to a variety of stripe artifacts in the sonogram; full stripes, partial stripes, fluctuating stripes, and unresponsive stripes. These give rise to ring artifacts of different kinds in the reconstructed image. The scattering of the scintillation photons can cause artifacts which are similar to beam hardening artifacts and reduce the resolution of the image. Here we present our practical approaches to tackle each such problem. These approaches are easy to implement and have low computational cost. The algorithms are freely available as open-source software.
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Sep 2019
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I12-JEEP: Joint Engineering, Environmental and Processing
Optics
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Diamond Proposal Number(s):
[14033]
Open Access
Abstract: High energy X-ray phase contrast tomography is tremendously beneficial to the study of thick and dense materials with poor attenuation contrast. Recently, the X-ray speckle-based imaging technique has attracted widespread interest because multimodal contrast images can now be retrieved simultaneously using an inexpensive wavefront modulator and a less stringent experimental setup. However, it is time-consuming to perform high resolution phase tomography with the conventional step-scan mode because the accumulated time overhead severely limits the speed of data acquisition for each projection. Although phase information can be extracted from a single speckle image, the spatial resolution is deteriorated due to the use of a large correlation window to track the speckle displacement. Here we report a fast data acquisition strategy utilising a fly-scan mode for near field X-ray speckle-based phase tomography. Compared to the existing step-scan scheme, the data acquisition time can be significantly reduced by more than one order of magnitude without compromising spatial resolution. Furthermore, we have extended the proposed speckle-based fly-scan phase tomography into the previously challenging high X-ray energy region (120 keV). This development opens up opportunities for a wide range of applications where exposure time and radiation dose are critical.
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Jun 2019
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I12-JEEP: Joint Engineering, Environmental and Processing
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Ramzi
Al-agele
,
Emily
Paul
,
Sophie
Taylor
,
Charlotte
Watson
,
Craig
Sturrock
,
Michael
Drakopoulos
,
Robert C.
Atwood
,
Catrin S.
Rutland
,
Nicola
Menzies-gow
,
Edd
Knowles
,
Jonathan
Elliott
,
Patricia
Harris
,
Cyril
Rauch
Open Access
Abstract: Global inequalities in economic access and agriculture productivity imply that a large number of developing countries rely on working equids for transport/agriculture/mining. Therefore, the understanding of hoof conditions/shape variations affecting equids' ability to work is still a persistent concern. To bridge this gap, using a multi-scale interdisciplinary approach, we provide a bio-physical model predicting the shape of equids’ hooves as a function of physical and biological parameters. In particular, we show (i) where the hoof growth stress originates from, (ii) why the hoof growth rate is one order of magnitude higher than the proliferation rate of epithelial cells and (iii) how the soft-to-hard transformation of the epithelium is possible allowing the hoof to fulfil its function as a weight-bearing element. Finally (iv), we demonstrate that the reason for hoof misshaping is linked to the asymmetrical design of equids' feet (shorter quarters/long toe) together with the inability of the biological growth stress to compensate for such an asymmetry. Consequently, the hoof can adopt a dorsal curvature and become ‘dished’ overtime, which is a function of the animal's mass and the hoof growth rate. This approach allows us to discuss the potential occurrence of this multifaceted pathology in equids.
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Jun 2019
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[7858]
Open Access
Abstract: Residual stress/strain and microstructure used in additively manufactured material are strongly dependent on process parameter combination. With the aim to better understand and correlate process parameters used in electron beam melting (EBM) of Ti-6Al-4V with resulting phase distributions and residual stress/strains, extensive experimental work has been performed. A large number of polycrystalline Ti-6Al-4V specimens were produced with different optimized EBM process parameter combinations. These specimens were post-sequentially studied by using high-energy X-ray and neutron diffraction. In addition, visible light microscopy, scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) studies were performed and linked to the other findings. Results show that the influence of scan speed and offset focus on resulting residual strain in a fully dense sample was not significant. In contrast to some previous literature, a uniform α- and β-Ti phase distribution was found in all investigated specimens. Furthermore, no strong strain variations along the build direction with respect to the deposition were found. The magnitude of strain in α and β phase show some variations both in the build plane and along the build direction, which seemed to correlate with the size of the primary β grains. However, no relation was found between measured residual strains in α and β phase. Large primary β grains and texture appear to have a strong effect on X-ray based stress results with relatively small beam size, therefore it is suggested to use a large beam for representative bulk measurements and also to consider the prior β grain size in experimental planning, as well as for mathematical modelling.
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Feb 2019
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Electrical Engineering
Mechanical Engineering
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Open Access
Abstract: I12 is a high-energy imaging, diffraction and scattering beamline at Diamond. Its source is a superconducting wiggler with a power of approximately 9kW at 500 mA after the fixed front-end aperture; two permanent filters aim at reducing the power in photons below the operating range of the beamline of 50-150 keV, which accounts for about two-thirds of the total*. This paper focuses on the design and simulation process of the secondary permanent filter, a 4mm thick SiC disk. The first version of the filter was vulnerable to cracking due to thermally induced stress, so a new filter based on an innovative concept was proposed: a water-cooled shaft rotates, via a ceramic interface, the SiC disk; the disk operates up to 900 degrees C, and a copper absorber surrounding the filter dissipates the heat through radiation. We utilised analysis data following failure of an initial prototype to successfully model the heat flow using FEA. This model informed different iterations of the re-design of the assembly, addressing the issues identified. The operational temperature of the final product matches within a few degrees C the one predicted by the simulation.
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Dec 2018
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I12-JEEP: Joint Engineering, Environmental and Processing
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Lee
Aucott
,
Hongbiao
Dong
,
Wajira
Mirihanage
,
Robert
Atwood
,
Anton
Kidess
,
Shian
Gao
,
Shuwen
Wen
,
John
Marsden
,
Shuo
Feng
,
Mingming
Tong
,
Thomas
Connolley
,
Michael
Drakopoulos
,
Chris R.
Kleijn
,
Ian M.
Richardson
,
David J.
Browne
,
Ragnvald H.
Mathiesen
,
Helen
Atkinson
Diamond Proposal Number(s):
[8218, 7855]
Open Access
Abstract: Internal flow behaviour during melt-pool-based metal manufacturing remains unclear and
hinders progression to process optimisation. In this contribution, we present direct timeresolved
imaging of melt pool flow dynamics from a high-energy synchrotron radiation
experiment. We track internal flow streams during arc welding of steel and measure
instantaneous flow velocities ranging from 0.1ms−1 to 0.5ms−1. When the temperaturedependent
surface tension coefficient is negative, bulk turbulence is the main flow
mechanism and the critical velocity for surface turbulence is below the limits identified in
previous theoretical studies. When the alloy exhibits a positive temperature-dependent
surface tension coefficient, surface turbulence occurs and derisory oxides can be entrapped
within the subsequent solid as result of higher flow velocities. The widely used arc welding and the emerging arc additive manufacturing routes can be optimised by controlling internal
melt flow through adjusting surface active elements.
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Dec 2018
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I12-JEEP: Joint Engineering, Environmental and Processing
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Open Access
Abstract: Synchrotron-based X-ray micro-tomography systems often suffer severe ring artifacts in reconstructed images. In sinograms the artifacts appear as straight lines or stripe artifacts. These artifacts are caused by the irregular response of a detecting system giving rise to a variety of observed types of stripes: full stripes, partial stripes, fluctuating stripes, and unresponsive stripes. The use of pre-processing techniques such as distortion correction or phase retrieval blurs and enlarges these stripes. It is impossible for a single approach to remove all types of stripe artifacts. Here, we propose three techniques for tackling all of them. The proposed techniques are easy to implement; do not generate extra stripe artifacts and void-center artifacts; and give superior quality on challenging data sets and in comparison with other techniques. Implementations in Python and a challenging data set are available for download.
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Oct 2018
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B16-Test Beamline
I12-JEEP: Joint Engineering, Environmental and Processing
Optics
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Diamond Proposal Number(s):
[14033]
Open Access
Abstract: X-ray phase-contrast imaging can substantially enhance image contrast for weakly absorbing samples. The fabrication of dedicated optics remains a major barrier, especially in high-energy regions (i.e. over 50 keV). Here, the authors perform X-ray phase-contrast imaging by using engineered porous materials as random absorption masks, which provides an alternative solution to extend X-ray phase-contrast imaging into previously challenging higher energy regions. The authors have measured various samples to demonstrate the feasibility of the proposed engineering materials. This technique could potentially be useful for studying samples across a wide range of applications and disciplines.
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Jul 2018
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[9880]
Open Access
Abstract: A novel, low-alloy steel has been designed for use in the oil and gas industry. Its high strength and hydrogen trapping potential are derived from a martensitic microstructure containing a dispersion of fine vanadium–molybdenum alloy carbides that evolve during tempering. In this second paper, the effect of quench rate from austenitisation and tempering conditions are investigated with respect to the microstructure. The alloy loses its tempering resistance following slow-cooling from austenitisation as a result of MC precipitation, leading to vanadium depletion and significant MC coarsening. This is predicted using computer simulation and confirmed by high energy X-ray diffraction, combined with electron microscopy.
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Jul 2018
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I12-JEEP: Joint Engineering, Environmental and Processing
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Donal P.
Finegan
,
Eric
Darcy
,
Matthew
Keyser
,
Bernhard
Tjaden
,
Thomas M. M.
Heenan
,
Rhodri
Jervis
,
Josh J.
Bailey
,
Nghia T.
Vo
,
Oxana V.
Magdysyuk
,
Michael
Drakopoulos
,
Marco Di
Michiel
,
Alexander
Rack
,
Gareth
Hinds
,
Dan J. L.
Brett
,
Paul
Shearing
Diamond Proposal Number(s):
[13884]
Open Access
Abstract: As the energy density of lithium-ion cells and batteries increases, controlling the outcomes of thermal runaway becomes more challenging. If the high rate of gas generation during thermal runaway is not adequately vented, commercial cell designs can rupture and explode, presenting serious safety concerns. Here, ultra-high-speed synchrotron X-ray imaging is used at >20 000 frames per second to characterize the venting processes of six different 18650 cell designs undergoing thermal runaway. For the first time, the mechanisms that lead to the most catastrophic type of cell failure, rupture, and explosion are identified and elucidated in detail. The practical application of the technique is highlighted by evaluating a novel 18650 cell design with a second vent at the base, which is shown to avoid the critical stages that lead to rupture. The insights yielded in this study shed new light on battery failure and are expected to guide the development of safer commercial cell designs.
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Oct 2017
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