Tidal power, or the use of tides for electricity production, exists in many forms including tidal barrages, which exploit tidal head differentials, and turbines placed directly in regions with large tidal current velocities. The latter is actively being investigated in many countries around the world as a means of providing renewable and wholly predictable electricity (cf. wind, solar and wave power). The expansion of the in-stream tidal industry is hindered however by several factors including: turbine durability, deployment and maintenance costs, and the lack of abundant locations which meet the necessary current velocities for turbine start-up and economic power production. A new novel type of augmentation device, entitled the ‘Tidal Acceleration Structure’ or TAS (Canadian patent pending 2644792), has been proposed as a solution to the limited number of coastal regions which exhibit fast tidal currents. In preliminary investigations, the TAS, a simple Venturi section consisting of walls extending from the seafloor to above the high water mark in an hourglass shape, was found as able to more than double current velocities entering the device. The results indicated a significant advantage over other current channeling technologies and thus the need for more in-depth investigations. The main objective of the present study was to optimise the design of the TAS and to predict the power that a turbine placed within it could extract from flow. To do this, two principal methods were employed. Firstly, a 1:50 scale model of the TAS was tested and its shape optimised in a 1.5 m wide flume. Secondly, a 3D numerical model (ANSYS Fluent) was used for comparison with the experimental results. During the tests, a TAS configuration was found that could accelerate upstream velocities by a factor of 2.12. In separate tests, turbines were simulated using Actuator Disc Theory and porous plates. The TAS-plate combination was found to be able to extract up to 4.2 times more power from flow than the stand-alone plate, demonstrating that the TAS could provide turbines with a significant advantage in slower currents. Though further research is needed, including the testing of a larger TAS model in conjunction with a small in-stream turbine, the results of this thesis clearly demonstrate the potential of the TAS concept to unlock vast new areas for tidal energy development.

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Master of Science / Department of Geology / Allen W. Archer / Abstract This study compares the tidally influenced facies found within the Tonganoxie Sandstone Member (Stranger Formation, Douglas Group) (Upper Pennsylvanian) of northeastern Kansas with similar facies directly observed in the upper intertidal mudflats of Turnagain Arm of Cook Inlet (Alaska, USA). The two settings contain strikingly similar facies that are characteristic of upper macrotidal estuaries with a strong influence of tidal activities. Identical aspects and features found within both settings include rhythmic vertical variation in stratum thicknesses (cyclic tidal rhythmites), high estimated sedimentation and aggradation rates, and biogenic and physical sedimentary structures (e.g., drag marks, raindrop impressions, arthropod traces and tetrapod trackways, zigzag burrows, runoff washouts, and upright trees, among others). Tidal rhythmites are the most important evidence that is indicative of the tidal influence on the depositional processes of these two study areas. Such cyclic tidal rhythmites have been reported and described from several Carboniferous settings in the eastern USA. Modern analogs to these Carboniferous rhythmites are usually found within upper macrotidal estuarine depositional environments, especially within fluvio-estuarine transitional zones. These environments are distributed over a wide range of modern latitudes. Using cyclic tidal rhythmites as modern analogs for interpreting similar ancient facies is a powerful tool for paleogeographic and paleoenvironmental reconstructions, although it is somewhat a new approach.

The Magellanic System at a distance of 50 kpc from the Milky Way (MW), is a prime target in the study of stellar populations, star formation histories and galactic dynamics in low metallicity environments. The Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) have been observed in great depth, however there has been somewhat less interest in the Magellanic Bridge connecting the two and only more recently has the interest surged in the Magellanic Stream, which trails the Clouds between them and the MW. The Magellanic Bridge has a known younger stellar population dating back to Irwin’s observations (Irwin et al., 1990), only more recently has an older population been confirmed in the Bridge by Bagheri et al. (2013) and No¨el et al. (2013), while the Magellanic Stream is known to contain gas only with no stellar component. The estimated ages of the Bridge and Stream are 200 Myr (Bekki, 2007) and 2 Gyr (Diaz and Bekki, 2012) respectively, with the postulated Bridge formation from a tidal interaction between the Clouds. The formation of the Stream is less well understood with different models using varying assumptions and parameters such as Besla et al. (2012) and Nidever et al. (2010), including possibilities that the Clouds were historically bound or un-bound, and that the MW may or may not have been involved in the Stream formation. The work in this thesis makes use of different methods of removing the Galactic foreground population in the direction of the Magellanic Bridge and Stream to create cleaned catalogues of these regions. Various methods of analysis are applied to the cleaned catalogues in this work to identify stellar populations in the Bridge and Stream and density variations in the Bridge, including the production of CMDs and two-colour diagrams, fitting isochrones to the observational data, creating stellar density maps and studying spatial variations. This work contains the first published confirmation that the Bridge contains an older population of stars from public catalogues, which is supported with observations of the older population in recent deeper surveys, and confirmed with spectroscopic follow up observations. The young population has ages within the age of the Bridge ( 200 − 500 Myr) and are likely to have formed in-situ, in regions of high density gas closest to the SMC. The number of young blue objects in the Bridge tiles is greater towards the SMC and decreases towards the LMC. Populations identified here reach ages up to 3 Gyr are likely to have been drawn into the Bridge from the Clouds at formation. The key results from this work are that an older Bridge stellar population has been identified and confirmed, indicating that stars as well as gas were drawn into the Bridge at its creation. The fact that the younger population has the highest density away from the main concentration of hydrogen show that the gas within the Bridge has been displaced by ram pressure, most likely due to the Clouds moving through the Galactic halo. Less concrete results in this work reveal a puzzling populetion of objects within the Magellanic Stream, which could be stellar in nature and with follow up work, could be the first observation of Stream objects. This work contributes to our understanding of the interaction between the LMC and SMC via the Stellar populations between them.

Ventricular fibrillation (VF) is a lethal heart rhythm that leads to cardiac arrest. It has been shown that amplitude spectral area (AMSA) in prolonged VF correlates with success of resuscitation. This study will compare traditional resuscitation with a novel resuscitation algorithm using AMSA and end-tidal carbon dioxide (ETCO2) to time defibrillations.VF will be induced in 60 swine. Resuscitation will commence after 10 minutes of untreated VF. Cases will receive defibrillation if AMSA is >19.8 mVHz and ETCO2 >20 mm of Hg, otherwise chest compressions will continue for another 90 seconds. Controls will have standard resuscitation. Sub group analysis will include effect of induced myocardial infarction (MI).End points will include survival, neurologic scores, duration of resuscitation efforts, and number of defibrillations.This experiment will establish whether using AMSA and ETCO2 to time defibrillations results in superior resuscitation compared with standard techniques.

We investigate the uses of gravitational lensing for analysing the dark matter haloes around galaxies, comparing galaxies within groups and clusters to those in the field. We consider two cases: when only photometric redshift data is available, and when spectroscopic redshift data is available for a sufficiently large sample of galaxies. For the case of data with photometric redshifts, we analyse the CFHTLenS dataset. This dataset is derived from the CFHTLS-Wide survey, and encompasses 154 deg^2 of high-quality shape data. Using the photometric redshifts to estimate local density, we divide the sample of lens galaxies with stellar masses in the range 10^9 Msun to 10^10.5 Msun into those likely to lie in high-density environments (HDE) and those likely to lie in low-density environments (LDE). Through comparison with galaxy catalogues extracted from the Millennium Simulation, we show that the sample of HDE galaxies should primarily (~61%) consist of satellite galaxies in groups, while the sample of LDE galaxies should consist of mostly (~87%) non-satellite (field and central) galaxies. Comparing the lensing signals around samples of HDE and LDE galaxies matched in stellar mass, we show that the subhaloes of HDE galaxies are less massive than those around LDE galaxies by a factor 0.65+/-0.12, significant at the 2.9 sigma level. A natural explanation is that the haloes of satellite galaxies are stripped through tidal effects in the group environment. Our results are consistent with a typical tidal truncation radius of ~40 kpc. For the case of data with spectroscopic redshifts, we analyse the GAMA-I and the ongoing GAMA-II surveys. We demonstrate the possibility of detecting tidal stripping of dark matter subhaloes within galaxy groups using weak gravitational lensing. We have run ray-tracing simulations on galaxy catalogues from the Millennium Simulation to generate mock shape catalogues. The ray-tracing catalogues assume a halo model for galaxies and groups, using various models with different distributions of mass between galaxy and group haloes to simulate different stages of group evolution. Using these mock catalogues, we forecast the lensing signals that will be detected around galaxy groups and satellite galaxies, as well as test two different methods for isolating the satellites' lensing signals. A key challenge is to determine the accuracy to which group centres can be identified. We show that with current and ongoing surveys, it will possible to detect stripping in groups of mass 10^12 Msun to 10^15 Msun.

The Transverse Horizontal Axis Water Turbine (THAWT) has been proposed as a tidal device which can be easily scaled and requires fewer foundations, bearings seals and generators than a more conventional axial-flow device. The THAWT device is a horizontally deployed variant of the Darrieus cross-flow turbine, in which the blades can be oriented into a truss configuration to produce long, stiff multi-bay rotors. This thesis establishes and combines a set of numerical models, which predict the hydrodynamic and structural performance of the THAWT device, with sufficient confidence to assess the feasibility of such a device at a full scale installation and to optimise its performance. Tests of 1/20th scale experimental models of the THAWT device have demonstrated that the truss configured device is capable of producing power with an efficiency close to that of the parallel configured turbine. In addition, variations in the configuration of the scale models have indicated how several design parameters affect the hydrodynamic performance of the device. A two-dimensional Navier-Stokes blade element model has been developed, in which the THAWT device is represented using an actuator cylinder. The addition of a hydrostatic free surface deformation correction has resulted in a model which is capable of matching experimental results with sufficient fidelity and accuracy. Blade loads from the numerical hydrodynamic model have been applied to a beam finite element analysis, to predict the stresses induced in the hydrofoils of the THAWT device. The numerical and hydrodynamic models are combined with a Linear Channel Momentum model to predict the performance of the THAWT device at a full scale tidal location. The effect that the device has on the channel flow indicates how much energy is available for extraction and how this energy might be most efficiently obtained. When considering material fatigue the analysis suggests that the structural design considerations dominate over the hydrodynamic considerations.

We present a brief history of Galactic astrophysics, and explain the origin of halo substructure in the Milky Way Galaxy. We motivate our study of the dynamics of tidal streams in our Galaxy by highlighting the tight constraints that analysis of the trajectories of tidal streams can place on the form of the Galactic potential. We address the reconstruction of orbits from observations of tidal streams. We upgrade the geometrodynamical scheme reported by Binney (2008) and Jin & Lynden-Bell (2007), which reconstructs orbits from streams using radial-velocity measurements, to allow it to work with erroneous input data. The upgraded algorithm can correct for both statistical error on observations, and systematic error due to streams not delineating individual orbits, and given high-quality but realistic input data, it can diagnose the potential with considerable accuracy. We complement the work of Binney (2008) by deriving a new algorithm, which reconstructs orbits from streams using proper-motion data rather than radial-velocity data. We demonstrate that the new algorithm has a similar potency for diagnosing the Galactic potential. We explore the concept of Galactic parallax, which arises in connection with our proper-motion study. Galactic parallax allows trigonometric distance calculation to stars at 40 times the range of conventional parallax, although its applicability is limited to only those stars in tidal streams. We examine from first principles the mechanics of tidal stream formation and propagation. We find that the mechanics of tidal streams has a natural expression in terms of action-angle variables. We find that tidal streams in realistic galaxy potentials will generally not delineate orbits precisely, and that attempting to constrain the Galactic potential by assuming that they do can lead to large systematic error. We show that we can accurately predict the real-space trajectories of streams, even when they differ significantly from orbits.

Channel constrictions in which strong currents are mainly driven by tidal processes represent sites with high potential for harvesting renewable and predictable tidal stream energy. Tidal Current Turbines (TCTs) deployed in arrays appear to be the most promising solution to efficiently capturing this carbon neutral energy resource. However to ensure the sustainable character of such projects, the balance between power extraction maximization and environmental impact minimization must be found so that device layout optimization takes into account environmental considerations. This is particularly appropriate since both resource and impact assessments go intrinsically hand in hand. The present method proposes the use and adaptation of ocean circulation models as an assessment tool framework for tidal current turbine (TCT) array-layout optimization. By adapting both momentum and turbulence transport equations of an existing model, the present TCT representation method is proposed to extend the actuator disc concept to 3-D large scale ocean circulation models. Through the reproduction of physical experiments to reasonable accuracy, grid and time dependency tests and an up-scaling exercise, this method has shown its numerical validity as well as its ability to simulate accurately both momentum and turbulent turbine-induced perturbations in the wake. These capabilities are demonstrated for standalone devices and device arrays, and are achieved with a relatively short period of computation time. Consequently the present TCT representation method is a very promising basis for the development of a TCT array layout optimization tool. By applying this TCT representation method to realistic cases, its capability is demonstrated for power capture assessment and prediction of hydrodynamic interactions as would be required during the layout deployment optimization process. Tidal energy has seen considerable development over the last decade and the first commercial deployments are likely to take place within the next 5 years. It is hoped that this new tool and the numerical approaches described herein will contribute to the development of TCT array power plants around the world.

Kinetic energy extraction devices for ocean and river flows are often located in the vicinity of the fluid free surface. This differs from wind turbines where the atmosphere may be considered to extend to infinity for the purposes of numerical modelling. As most kinetic energy extraction devices are based on lifting surfaces, a numerical model is sought which can model both lifting and free surface flows. One such model is the boundary element method which has been successfully applied to free surface problems and to lifting flows as well as the combined problem. This study seeks to develop a high order boundary element method that is capable of modelling unsteady lifting and free surface flows in three dimensions. Although high order formulations of boundary element methods are common for free surface problems, providing improved accuracy and computational time, their usage for lifting flows is less frequent. This may be due to the hypersingular boundary integral equation (HBIE) which must be solved in order to find the velocity of the vortex wakes behind lifting surfaces. In previous lifting flow studies using high order boundary element methods the wake velocities have been determined at the element centres and then interpolated to the collocation points. Not until the paper of Gray et al. (2004b) has a method been available for the direct solution of the HBIEs at the edges of three dimensional high order elements with C0 continuous interfaces. The solution employs a technique known as the Galerkin boundary element method. This study shows, for the first time, that the Galerkin boundary element method is applicable to the solution of the HBIE on the vortex wake of a lifting body. The application of the technique is then demonstrated as part of the numerical model developed herein. The model is based on the high order boundary element method developed by Xu (1992) for non-linear free surface flows. This formulation is extended to include steady uniform flow throughout the computational domain as well as the presence of lifting and non-lifting bodies. Several verification cases are implemented to test the accuracy of the model.