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Hydraulic turbines contribute to 60% of renewable energy in the world; however, they also entail some adverse effects on the aquatic ecology system. One such effect is their excessive noise and vibration. To minimize this effect, one of the most effective and feasible solutions is to modify the design of the turbine rotor blade by introducing a skew. In this study, two 0.3-meter tidal turbines with 0-degree (no-skewness) and positive 90-degree skewness made of stainless steel 316L were designed and printed using a 3-D printing powder bed fusion technique. These rotors were then tested at the Emerson Cavitation Tunnel (ECT) at Newcastle University, UK, and the variation in the skewness of the blades of the turbines as a function of the power coefficient on a given tip speed ratio (TSR) value was ascertained. Results showed that the highly skewed rotor had significantly lower drag and torque fluctuations, with a slight decrease in efficiency compared to the non-skewed one, which warrants further investigation on the effect of added skew to reduce vibration and noise. Numerical simulations were also performed for verification and validation of the experimental tests, using the H45 dynamometer at the ECT. A comprehensive software code for propellers and tidal turbines, ROTORYSICS, was used to examine the cavitation effect of the two rotors; a comparison was made for both, with and without cavitation. The results indicate that for a high immersion depth of tidal turbine rotors, cavitation rarely occurs, but for hydrokinetic turbines that are installed on dams in rivers and falls, cavitation could be a serious concern. It was concluded that the 0-degree skewed rotor is more hydrodynamically efficient than the 90-degree skewed rotor. [ABSTRACT FROM AUTHOR]

Untreated dental caries affects children in the UK, with significant burden to the child, family and health service. High quality bitewing radiography is more effective than clinical observation alone at detecting proximal caries in children. Accurate diagnosis before cavitation allows preventive rather than operative management. Research has demonstrated that most children find bitewing radiography acceptable. It is therefore vital that bitewing radiographs of children are taken as per national guidance in general practice. CPD/Clinical Relevance: Timely and high quality bitewing radiography is required for accurate diagnosis and treatment planning in children. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes theoretical and experimental methods for characterising the performance of a 25kHz sonochemical reactor (RV-25), which is being developed as a reference facility for studying acoustic cavitation at the National Physical Laboratory (NPL). Field measurements, acquired in different locations inside the sonoreactor, are compared with finite element models at different temperatures, showing that relatively small temperature variations can result in significant changes in the acoustic pressure distribution (and consequent cavitation activity). To improve stability, a deeper insight into the way energy is transferred from the power supply to the acoustic field is presented, leading to criteria – based on modal analysis – to dimension and verify an effective temperature control loop. The simultaneous use of measurements and modelling in this work produced guidelines for the design of multi-frequency cylindrical sonoreactors, also described. [Copyright &y& Elsevier]

Abstract: Approximately half a million people are killed worldwide each year by firearms. Ballistic injury is uncommon in the UK, but confusion may arise if such injuries present to Accident and Emergency Departments. The combination of confusion and an unfamiliar injury pattern is not ideal in the resuscitation of injured casualties, and the situation is worse if there are multiple casualties. One must be familiar with the concepts of ballistic injury and its pathophysiology to minimize the adverse effects; understanding energy transfer and the clinical consequences of ballistic wounding guide subsequent management. The physics of blast can be complex, but an awareness of the basic principles clarifies how injuries are produced and their severity. The basic principles of war surgery are detailed, and the concept of damage-control surgery in the management of missile and explosive wounds in the physiologically exhausted patient is discussed. [Copyright &y& Elsevier]