Verification of micro-scale photogrammetry for smooth three-dimensional object measurement

By using sub-millimetre laser speckle pattern projection we show that photogrammetry systems are able to measure smooth three-dimensional objects with surface height deviations less than 1 μm. The projection of laser speckle patterns allows correspondences on the surface of smooth spheres to be found, and as a result, verification artefacts with low surface height deviations were measured. A combination of VDI/VDE and ISO standards were also utilised to provide a complete verification method, and determine the quality parameters for the system under test. Using the proposed method applied to a photogrammetry system, a 5 mm radius sphere was measured with an expanded uncertainty of 8.5 μm for sizing errors, and 16.6 μm for form errors with a 95 % confidence interval. Sphere spacing lengths between 6 mm and 10 mm were also measured by the photogrammetry system, and were found to have expanded uncertainties of around 20 μm with a 95 % confidence interval

Explosive blast resistance of naval composites: effects of fiber, matrix, and interfacial bonding

[No abstract available

Comparative assessment of the explosive blast performance of carbon and glass fibre-polymer composites used in naval ship structures

An experimental investigation is presented into the explosive blast response of fibre-reinforced polymer laminates used in naval ship structures. Blast tests using plastic explosive charges were performed in air on square target plates made of carbon-polyester, glass-polyester, carbon-vinyl ester or glass-vinyl ester laminates, which are composite materials used in naval ships. The laminates were dynamically loaded by shock waves of increasing pressure and impulse, and the deformation, damage and residual mechanical properties were determined. The amount of blast-induced damage and the post-blast mechanical properties depend on both the fibre reinforcement and polymer matrix. E-glass laminates have higher resistance to blast-induced delamination cracking and tow rupture than carbon fibre composites. Furthermore, glass or carbon fibre laminates with a vinyl ester matrix have superior blast damage resistance compared to composites with a polyester matrix. The higher damage resistance is attributed to the higher flexural strain energy capacity and interlaminar fracture toughness properties of laminates containing glass fibres or vinyl ester matrix

Effect of seawater immersion on the explosive blast response of a carbon fibre-polymer laminate

Explosions are an ever-present risk to laminates used in naval ships, submarines and offshore oil/gas platforms that are immersed in seawater. This study determines whether the absorption of water by a carbon fibre laminate changes its deformation response and damage resistance when impulsive loaded by an explosive blast. The stiffness and strength properties of the laminate were reduced with increasing immersion time in seawater up to and beyond the point of saturation. Explosive blast tests of increasing shock wave impulse were performed on the laminate before immersion and when in the saturated and beyond saturated conditions. Softening and weakening of the laminate caused by absorbed water reduced the resistance against deformation and damage when subjected to an explosive blast. The amount of blast-induced damage to the laminate increased with the immersion time in seawater due to plasticisation of the polymer matrix and weakening of the fibre-matrix interphase region

Which clinical features distinguish infl icted from non-infl icted brain injury? A systematic review. Arch Dis Child

ABSTRACT Aim: A systematic review of the scientific literature to define clinical indicators distinguishing inflicted (iBI) from non-inflicted brain injury (niBI). Methods: An all language literature search of 20 electronic databases, websites, references and bibliographies from 1970-2008 was carried out. Relevant studies were independently reviewed by two trained reviewers, with a third review where required. Inclusion criteria included primary comparative studies of iBI and niBI in children aged ,18 years, with high surety of diagnosis describing key clinical features. Multilevel logistic regression analysis was conducted, determining the positive predictive value (PPV) and odds ratios (OR) with p values for retinal haemorrhage, rib/long bone/skull fractures, apnoea, seizures and bruising to head/neck. Results: 8151 studies were identified, 320 were reviewed and 14 included, representing 1655 children, 779 with iBI. Gender was not a discriminatory feature. In a child with intracranial injury, apnoea (PPV 93%, OR 17.06, p,0.001) and retinal haemorrhage (PPV 71%, OR 3.504, p = 0.03) were the features most predictive of iBI. Rib fractures (PPV 73%, OR 3.03, p = 0.13) had a similar PPV to retinal haemorrhages, but there were less data for analysis. Seizures and long bone fractures were not discriminatory, and skull fracture and head/neck bruising were more associated with niBI, although not significantly so. Conclusions: This systematic review shows that apnoea and retinal haemorrhage have a high odds ratio for association with iBI. This review identifies key features that should be recorded in the assessment of children where iBI is suspected and may help clinicians to define the likelihood of iBI