Model wave impulse loads on caisson breakwater aeration, scale and structural response

Merged with duplicate record 10026.1/834 on 22.03.2017 by CS (TIS)The prediction of wave impact loads on prototype caisson breakwaters from the results of physical model tests is considered, with particular attention given to the effects of air, breaker shape, structural response and scale. A review of related literature is presented from which it is concluded that the different aspects of the problem may be related through the force impulse. Large scale soliton impacts are used to show the importance of entrapped air in determining the form of the load time history. Small scale waves with artificially high levels of entrained air and highly controlled drop impacts are used to show and quantify an inverse relationship between entrained air and impact load maxima. Specially developed aeration probes and analysis techniques are used to show the influence of entrapped air on pressure maxima and quantify entrained air levels in small scale fresh water breaking waves. A definition of the force impulse is proposed and used to investigate its variation with breaker shape. The impulse magnitude is shown to be relatively invariant for regular wave impacts compared to a large scatter in impulse form. A numerical model of caisson dynamics is used to predict structural motion and to calculate a series of dynamic amplification factors. The prediction of structural response to obtain effective static loads through the use of these factors is investigated and achieved through the adoption of an 'equivalent impulse' concept. The scatter in impulse form is found to cause large variations in effective static loads between nominally identical impact events. The equivalent impulse concept is used to solve this problem. A comparison is made between the form and magnitude of the force impulses of the small and large scale waves. The results indicate that the impulse magnitude may be relatively free of scale effects. An example is given in which the results of a small scale test are interpreted, scaled and processed to account for the effects of entrained air and structural response in order to predict large scale effective static loads. These are shown to compare well with predictions made using measured large scale force time histories and the numerical caisson model

Communicating simulation outputs of mesoscale coastal evolution to specialist and non-specialist audiences

Coastal geomorphologists and engineers worldwide are increasingly facing the non-trivial challenge of visualising and communicating mesoscale modelling assumptions, uncertainties and outcomes to both coastal specialists and decision-makers. Visualisation of simulation outcomes is a non-trivial problem because the more abstract scientific visualisation techniques favoured by specialists for data exploration and hypothesis-testing are not always as successful at engaging decision-makers and planners. In this paper, we show how the risk of simulation model outcomes becoming disconnected from more realistic visualisations of model outcomes can be minimised by using the Coastal Modelling Environment (CoastalME). CoastalME is a modelling framework for coastal mesoscale morphological modelling that can achieve close linkages between the scientific model abstractions, in the form of lines, areas and volumes, and the 3D representation of topographic and bathymetric surfaces and shallow sub-surface sediment composition. We propose and illustrate through the study case of Happisburgh (eastern England, UK), a transparent methodology to merge the required variety of data types and formats into a 3D-thickness model that is used to initialise a simulation. We conclude by highlighting some of the barriers to the adoption of the methodology proposed

Loop spaces and choreographies in dynamical systems

We consider a subset of the set of solutions to the n-body problem, termed choreographies, which involve a motion of particles where each follows the same path in space with a fixed time delay. Focusing on planar choreographies, we use the action of symmetry groups on the spatial and temporal motion of such systems to restrict a space of loops and study the topology of the resulting manifolds. As well as providing a framework of notation and terminology for the study of such systems, we prove various useful properties which allow us to classify the possible groups of symmetries, and discuss which are likely to be realisable as that of a motion of bodies.EThOS - Electronic Theses Online ServiceForrest RecruitmentGBUnited Kingdo

Effect of vaccine storage temperatures and dose rate on antibody responses to foot and mouth disease vaccination in Cambodia

A field study investigated the effects of foot and mouth disease vaccine storage temperature for 7 days (frozen, refrigerated or held at ambient temperature) and dose (half or full dose) on the serological response to vaccination. It utilised a complete factorial design replicated on 18 smallholder cattle farms in three villages in Pursat province, Cambodia. Antibody responses from the 108 cattle involved were assessed by serological examination of blood samples collected at primary vaccination (day 0), at booster vaccination (day 30) and finally at 60 days post primary vaccination. Vaccination responses to the inactivated vaccine were assessed by testing for antibodies directed against FMD structural proteins in a liquid-phase blocking ELISA (LPBE test) and differentiated from responses to natural infection by examining antibody titres against non-structural viral proteins (NSPE test). LPBE results indicated that the mean log10 LPBE antibody titres of all experimental cattle increased from below protective levels at day 0 to protective levels at 30 days post primary vaccination, and increased further at 60 days post primary vaccination. Storage at ambient temperature for 1 week had no effect on antibody response to vaccination. However, freezing the vaccine for a week or use of a half dose resulted in significant reduction in titres at day 60 (P = 0.04 and P = 0.02, respectively). The results of this study reinforce the need to store FMD vaccines within the range recommended by the manufacturers and to adhere to the specified dosage instructions

The physics of turbulence localised to the tokamak divertor volume

Fusion power plant designs based on magnetic confinement, such as the tokamak design, offer a promising route to sustainable fusion power but require robust exhaust solutions capable of tolerating intense heat and particle fluxes from the plasma at the core of the device. Turbulent plasma transport in the region where the interface between the plasma and the materials of the device is handled - called the divertor volume - is poorly understood, yet impacts several key factors ultimately affecting device performance. In this article a comprehensive study of the underlying physics of turbulence in the divertor volume is conducted using data collected in the final experimental campaign of the Mega Ampere Spherical Tokamak device, compared to high fidelity nonlinear simulations. The physics of the turbulence is shown to be strongly dependant on the geometry of the divertor volume - a potentially important result as the community looks to advanced divertor designs with complex geometry for future fusion power plants. These results lay the foundations of a first-principles physics basis for turbulent transport in the tokamak divertor, providing a critical step towards a predictive understanding of tokamak divertor plasma solutions

Multidisciplinary consensus guideline for the diagnosis and management of spontaneous intracranial hypotension

BACKGROUND: We aimed to create a multidisciplinary consensus clinical guideline for best practice in the diagnosis, investigation and management of spontaneous intracranial hypotension (SIH) due to cerebrospinal fluid leak based on current evidence and consensus from a multidisciplinary specialist interest group (SIG). METHODS: A 29-member SIG was established, with members from neurology, neuroradiology, anaesthetics, neurosurgery and patient representatives. The scope and purpose of the guideline were agreed by the SIG by consensus. The SIG then developed guideline statements for a series of question topics using a modified Delphi process. This process was supported by a systematic literature review, surveys of patients and healthcare professionals and review by several international experts on SIH. RESULTS: SIH and its differential diagnoses should be considered in any patient presenting with orthostatic headache. First-line imaging should be MRI of the brain with contrast and the whole spine. First-line treatment is non-targeted epidural blood patch (EBP), which should be performed as early as possible. We provide criteria for performing myelography depending on the spine MRI result and response to EBP, and we outline principles of treatments. Recommendations for conservative management, symptomatic treatment of headache and management of complications of SIH are also provided. CONCLUSIONS: This multidisciplinary consensus clinical guideline has the potential to increase awareness of SIH among healthcare professionals, produce greater consistency in care, improve diagnostic accuracy, promote effective investigations and treatments and reduce disability attributable to SIH