An early Portuguese mariner's astrolabe from the Sodré Wreck‐site, Al Hallaniyah, Oman

A unique leaded‐gunmetal disc decorated with iconic Portuguese markings was recovered in 2014 during archaeological excavations at the Sodré shipwreck site in Al Hallaniyah, Oman. Initially the identity and function of the disc was unknown, although it did possess characteristics suggesting it could be an astrolabe. Laser imaging of the disc post conservation revealed regular scale marks on the limb of its upper right quadrant. Accurate digital measurements of the marks show them to be graded at close to 5‐degree intervals, thus confirming the identity of the disc as a mariner's astrolabe and the earliest known example discovered to date

Introducing 3D printed models as demonstrative evidence at criminal trials

This case report presents one of the first reported uses of a 3D printed exhibit in an English homicide trial, in which two defendants were accused of beating their victim to death. The investigation of this crime included a micro-CT scan of the victim's skull, which assisted the pathologist to determine the circumstances of the assault, in particular regarding the number of assault weapons and perpetrators. The scan showed two distinct injury shapes, suggesting the use of either two weapons or a single weapon with geometrically distinct surfaces. It subsequently served as the basis for a 3D print, which was shown in court in one of the first examples that 3D printed physical models have been introduced as evidence in a criminal trial in the United Kingdom. This paper presents the decision-making process of whether to use 3D printed evidence or not

Markov random field segmentation for industrial computed tomography with metal artefacts

X-ray Computed Tomography (XCT) has become an important tool for industrial measurement and quality control through its ability to measure internal structures and volumetric defects. Segmentation of constituent materials in the volume acquired through XCT is one of the most critical factors that influence its robustness and repeatability. Highly attenuating materials such as steel can introduce artefacts in CT images that adversely affect the segmentation process, and results in large errors during quantification. This paper presents a Markov Random Field (MRF) segmentation method as a suitable approach for industrial samples with metal artefacts. The advantages of employing the MRF segmentation method are shown in comparison with Otsu thresholding on CT data from two industrial objects

The Oxford dodo. Seeing more than ever before : X-ray micro-CT scanning, specimen acquisition and provenance

The Oxford Dodo (Raphus cucullatus) has been in the collections of the University of Oxford since 1683, first in the Ashmolean Museum and latterly in Oxford University Museum of Natural History. Prior to this the specimen was part of the collections of the Tradescants, father and son, and likely acquired between 1634 and 1656, in the Musæum Tradescantianum in what is now Vauxhall, south London. It has been thought probable that this specimen was once the live bird recorded in London by Sir Hamon L’Estrange in around 1638, but X-ray CT scanning of the skull for anatomical investigation has cast doubt on the provenance of the Oxford Dodo. The 3D visualisation revealed 115 metal particles embedded within the bone of the skull, concentrated in the left side of the skull. All but five of the particles are less than 1 mm in diameter and their location leads to the conclusion that they represent lead shot consistent with the bird being shot from the rear right of the head, perhaps with a ventral component. This forensic discovery leaves the provenance of the Oxford specimen uncertain but illustrates the value of non-invasive visualisation techniques in determining the potentially complex histories of unique museum objects

X-ray tomography studies on porosity and particle size distribution in cast in-situ Al-Cu-TiB2 semi-solid forged composites

X-ray computed tomography (XCT) was used to characterise the internal microstructure and clustering behaviour of TiB2 particles in in-situ processed Al-Cu metal matrix composites prepared by casting method. Forging was used in semi-solid state to reduce the porosity and to uniformly disperse TiB2 particles in the composite. Quantification of porosity and clustering of TiB2 particles was evaluated for different forging reductions (30% and 50% reductions) and compared with an as- cast sample using XCT. Results show that the porosity content was decreased by about 40% due to semi-solid forging as compared to the as-cast condition. Further, XCT results show that the 30% forging reduction resulted in greater uniformity in distribution of TiB2 particles within the composite compared to as-cast and the 50% forge reduction in semi-solid state. These results show that the application of forging in semi-solid state enhances particle distribution and reduces porosity formation in cast in-situ Al-Cu-TiB2 metal matrix composites

Quantifying the pathway and predicting spontaneous emulsification during material exchange in a two phase liquid system

Kinetic restriction of a thermodynamically favourable equilibrium is a common theme in materials processing. The interfacial instability in systems where rate of material exchange is far greater than the mass transfer through respective bulk phases is of specific interest when tracking the transient interfacial area, a parameter integral to short processing times for productivity streamlining in all manufacturing where interfacial reaction occurs. This is even more pertinent in high-temperature systems for energy and cost savings. Here the quantified physical pathway of interfacial area change due to material exchange in liquid metal-molten oxide systems is presented. In addition the predicted growth regime and emulsification behaviour in relation to interfacial tension as modelled using phase-field methodology is shown. The observed in-situ emulsification behaviour links quantitatively the geometry of perturbations as a validation method for the development of simulating the phenomena. Thus a method is presented to both predict and engineer the formation of micro emulsions to a desired specification

Review of high-speed imaging with lab-based x-ray computed tomography

X-ray computed tomography (CT) is frequently used for non-destructive testing with many applications in a wide range of scientific research areas. The difference in imaging speeds between synchrotron and lab-based scanning has reduced as the capabilities of commercially available CT systems have improved, but there is still a need for faster lab-based CT both in industry and academia. In industry high-speed CT is desirable for inline high-throughput CT at a higher resolution than currently possible which would save both time and money. In academia it would allow for the imaging of faster phenomena, particularly dynamic in-situ testing, in a lab-based setting that is more accessible than synchrotron facilities. This review will specifically highlight what steps can be taken by general users to optimise scan speed with current equipment and the challenges to still overcome. A critical evaluation of acquisition parameters across recent high-speed studies by commercial machine users is presented, indicating some areas that could benefit from the methodology described. The greatest impacts can be achieved by maximising spot size without notably increasing unsharpness, and using a lower number of projections than suggested by the Nyquist criterion where the anecdotal evidence presented suggests usable results are still achievable

X-ray computed tomography (XCT) and chemical analysis (EDX and XRF) used in conjunction for cultural conservation: the case of the earliest scientifically described dinosaur Megalosaurus bucklandii

This paper demonstrates the combined use of X-ray computed tomography (XCT), energy dispersive X-ray spectroscopy (EDX) and X-ray fluorescence (XRF) to evaluate the conservational history of the dentary (lower jaw) of Megalosaurus bucklandii Mantell, 1827, the first scientifically described dinosaur. Previous analysis using XCT revealed that the specimen had undergone at least two phases of repair using two different kinds of plaster, although their composition remained undetermined. Additional chemical analysis using EDX and XRF has allowed the determination of the composition of these unidentified plasters, revealing that they are of similar composition, composed dominantly of ‘plaster of Paris’ mixed with quartz sand and calcite, potentially from the matrix material of the Stonesfield Slate, with the trace presence of chlorine. One of the plasters unusually contains the pigment minium (naturally occurring lead tetroxide; Pb22+Pb4+O4) whilst the other seems to have an additional coating of barium hydroxide (Ba(OH)2), indicating that these likely represent two separate stages of repair. The potential of this combined approach for evaluating problematic museum objects for conservation is further discussed as is its usage in cultural heritage today

Using micro computed tomography to examine the larynx in cases of suspected strangulation- a comparison of case findings and control images

The examination of strangulation is one of the most challenging cause of death diagnoses encountered in forensic pathology. The injuries are often subtle and difficult to detect, especially in cases that lack superficial marks. Fractures of the laryngeal skeleton are commonly regarded as evidence of strangulation but these can be too subtle to be detected during autopsy. Micro-CT is a novel imaging technique that achieves a spatial resolution 1µm or less which lends itself to the examination of small and delicate structures such as the larynx. However, there is little information to date regarding the appearance of the larynx at this scale, thus complicating the interpretation of the micro-CT images. This study therefore uses micro-CT to examine ten larynges from strangulation deaths and to compare them to nineteen samples from donor individuals in order to distinguish between naturally occurring features and actual trauma. It was found that there are several features which mimic damage in the donor group. Using associated case information, initial trends and patterns of different strangulation methods were established

Design & manufacture of a high-performance bicycle crank by additive manufacturing

A new practical workflow for the laser Powder Bed Fusion (PBF) process, incorporating topological design, mechanical simulation, manufacture, and validation by computed tomography is presented, uniquely applied to a consumer product (crank for a high-performance racing bicycle), an approach that is tangible and adoptable by industry. The lightweight crank design was realised using topology optimisation software, developing an optimal design iteratively from a simple primitive within a design space and with the addition of load boundary conditions (obtained from prior biomechanical crank force–angle models) and constraints. Parametric design modification was necessary to meet the Design for Additive Manufacturing (DfAM)considerations for PBF to reduce build time, material usage, and post-processing labour. Static testing proved performance close to current market leaders with the PBF manufactured crank found to be stiffer than the benchmark design (static load deflection of 7.0±0.5 mm c.f. 7.67mm for a Shimano crank at a competitive mass (155g vs. 175g). Dynamic mechanical performance proved inadequate, with failure at 2495±125cycles; the failure mechanism was consistent in both its form and location. This research is valuable and novel as it demonstrates a complete work flow from design, manufacture, post-treatment, and validation of a highly loaded PBF manufactured consumer component, offering practitioners a validated approach to the application of PBF for components with application outside of the accepted sectors (aerospace, biomedical, autosports, space, and power generation)