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This thesis presents a study of tidal flow interaction with headland and island features. Wake development in the lee of topographic features can generate complex two- and three-dimensional flow structures. The primary objectives of the research are to (i) determine the suitability of traditional numerical modelling techniques for application in the coastal environment, (ii) elucidate the development of wake features in the coastal environment, and (iii) illustrate the impact of wake features on tidal mixing and dispersion processes. A numerical finite-difference model has been developed using standard methods to solve the two-dimensional Shallow Water Equations. The model has undergone an extensive validation and verification exercise. Comparisons of model output with field data and output from other numerical simulations presented in the literature confirms the suitability of the numerical model for investigating wake and eddy development in the coastal environment. The sequence of events necessary for a wake eddy to develop from flow separation through to eddy shedding has been elucidated using idealised numerical modelling cases. Simulation and interpretation of test cases obtained from the literature has confirmed these findings. Important differences between eddy shedding events in headland and island wakes have been identified. Symmetry of the governing equations has been confirmed as the source of numerical models' failure to reproduce eddy shedding around symmetrical islands. Mixing and dispersion around a headland in a deterministic tidal flow field is simulated. Lagrangian analysis techniques are required to properly interpret transport processes. The significant impact of transient eddy features generated by the headland is indicated by the mixing and dispersion diagrams presented. A defined front between the well mixed and unmixed regions of flow is apparent. This indicates the extent of the mixing zone. Dispersion of individual patches around the headland is described using a three stage process.

This thesis presents a performance evaluation of a micro horizontal axis wind turbine, investigates the use of particle image velocimetry (PIV) to capture the flow field around a rotating blade and to track water droplets in the flow. The testing was done in a low speed wind tunnel in a highly blocked configuration. The turbine was instrumented to measure rotational speed of the rotor, axial thrust and power output. Wind speed of the wake was measured with a Kiel probe. Performance characteristics were calculated and compared with the manufacturer’s published data and to power predictions by axial momentum theories. The turbine was shown to perform well and the manufacturer’s published data are accurate. Axial momentum theory over-predicts power by approximately 50%. It is shown that good PIV results can be obtained using a fog machine to seed the flow. Improved illumination and optics will be required to measure 3D flow close to the blade. Water droplets can be tracked but a shadowgraphy arrangement should be used to better visualize the droplets. The droplets also affect the rotational speed of the rotor such that capturing the blade in a consistent point in the field of view is problematic.

Particle image velocimetry was widely used in many kinds of flow field recently. It provides a global view of instantaneous fluid velocity without disturbs flow field. In the present study, the cylinder wake with momentum addition was measured by PIV. The Reynolds number was fixed at 465 and 535 with cylinder diameter 19mm. The flow¡¦s displacement was measured by tracking flow images of 50 diameter ployamid 12 particles. The mean velocity of the momentum interference from the cylinder surface were 21 and 52 mm/s, respectively. From the results, the wake region shrinks under momentum injection at 0˚, but enlarges at 30˚ to 90˚. Under momentum suction, the effect of the wake expands at 0˚. Although the down stream velocity becomes more uniform at 30˚ and 60˚, the wake region spreads when suction at 90˚. On the other hand, the velocity spectra by hot-film anemometry also give consistent results with PIV analysis.

To detect REM and wake stages in sleep, this study generates feature variables from the correlation of two-channel EOG signals and the amplitude of LEOG signal. By using the VQ method to quantize these signals into different codewords and by calculating the number of appearances of these codewords, we are able to establish a feature vector for every epoch of the recorded EOG signals. Via a three-stage process, the personalized classification accuracy for REM and wake sleep stages are about 95% and 86%, respectively. By combining these personalized classifiers to perform REM and wake stages detection for other unseen individuals, the classification accuracy for REM and wake sleep stages, the classification accuracy become 85% and 92%. However, the sensitivity for the wake stage detection is merely 52%.

No description available.

Lagrangian potential flow methods are a promising alternative to mainstream wind turbine aerodynamics tools such as blade element momentum methods and grid-based computation fluid dynamics approaches. Potential flow methods are relatively easy to setup and robust with respect to geometry. With the advent of numerical techniques such as the fast multipole method, potential flow methods can be made computationally fast. Viscous core modelling has led to improvements in accuracy and numerical robustness. A C++ programming library employing Prandtl-Weissinger lifting line wing models and tailorable potential flow wake models has been developed under the name LibAero. The library offers steady-state, periodic, and unsteady flow simulators that can be used interchangeably with wake models. (Periodic and unsteady simulation are still under development and validation.) Wake models are constructed from potential flow elements such as vortex particles, laments, and sheets. Fast multipole method, symmetry modelling, multigrid method, and relaxation iteration are utilized to accelerate the computation of element-by-element interactions. The computational performance is assessed and the numerical results are validated against wind tunnel experimental data from the MEXICO Project and the Tj reborg wind turbine. The results of steady-state simulations with respect to a variety of numerical options and rotor blade designs are presented and conclusions are drawn. / Graduate

Over the last century, the problem of a viscous flow past a sphere has received on-going attention due to its many engineering applications. These include combustion processes, sediment transport processes and atmospheric flow problems, where the sphere serves as a good model for more general bluff body particles. In these environments, particles may be subjected to both translational and rotational velocities. The objective of this study was to investigate the effect that sphere rotation, about an axis transverse to the freestream flow, has on the characteristics or the vertical wake structure and the forces exerted on the sphere. That was achieved by solving the time-dependant, incompressible Navier Stokes equations, using a highly accurate Fourier Chebyshev spectral collation method.

The object of this study is to discover whether Joyce's many allusions to events and personages from Ireland's history and mythology are incidental to the main narrative of Finnegans Wake, or whether they serve an intrinsic thematic and structural function. Chapter 2 examines the general theories which underlie Joyce's use of the past in his novel. From Vico he derived his conception of the cyclical progress of history, and from Bruno a notion of conflict based on the confrontation of opposites. In the writings of Quinet Joyce discovered a metaphor for recurrence in the image of flowers which continue to flourish regardless of the rise and fall of civilizations. These general concepts found in Irish dimension in the work of Stefan Czarnowski. He examined the process of mythologization by which St. Patrick became absorbed into the cultural mould of the earlier Celtic heroes, and provided a parallel for Joyce's identification of his characters which corresponding figures in the past. Furthermore, Czarnowski's concept of provisional death, in which heroes were preserved by a commemorative rites, reinforces the significance of the wake as a symbol of the hope of renewal. Joyce began work on Finnegans Wake by isolating certain themes from Ireland's past, and incorporating them into the fictional frame-work of six preliminary sketches. These sketches are studied in their earliest and final forms in chapter 3. The figures of Rodrick O'Connor, Tristan and Isolde. Kevin, Bishop Berkely and Patrick are the focus of the first four, while the theme of invasion is prominent in "Nannelujo", and the relationship of subjugated people to a conqueror in "Here Comes Everybody." By tracing the original themes to their inclusion in Finnegans Wake Joyce's treatment of his subjects is seen to develop from a mood of simple parody towards the juxtaposition of a multiplicity of parallel themes. The main emphasis of the novel went beyond the initial interest in history, as the concerns revealed by the isolation of themes from the past were developed in a fictional framework designed to be archetypal and representative, rather than historical and particular. Chapter 4 examines the relationship that Joyce set up between the brothers Shem and Shaun and their past. First as Mutt and Jute and later as Muta and Juva, they observe respectively the Battle of Ciontarf and the confrontation of the Archdruid and Patrick. Throughout the novel the oppositions of Shem and Shaun are frequently given an Irish dimension. Furthermore, in the chapters of Finnegans Wake devoted to Shaun, he adopts many attitudes associated with an insular Irish point of view. As Shaun the post, he is associated with Victorious, the messenger sent by the people of Ireland in a time of crisis to recall St. Patrick. Shaun does not succeed in his mission, but dreams of usurping Patrick's position himself. He is also the adovcace of violent means to achieve national aspirations, and, through his slogans are popular, they are also suspect. HCE himself, therefore, is forced to rise from his slumbers to propose an alternative, more tolerant, prospect from Ireland. Joyce's depiction of HCE has a consistent Irish dimension, studied in chapter 5. He is shown as an outsider, associated with the many invaders of Ireland, whose wider view of reality enables him to point a new way forward. He is the founder of a city culture, which object of suspicien for many. His roles include not only the hero Finn and Saint Patrick, but also Parnell, whose personality deeply divided the country. The lose of public confidence, which paralyses HCE's creativity, is expressed in Finnegans Wake by the image of the grave, in which HCE must sleep in the state of provisional death, awaiting the popular acceptance of a broad concept of national-hood, and the establishment of a new era by mutual consent. The themes which intersected Joyce at the outset of his novel developed through his adaptation of ideas gleaned from Vico, Bruno and Czarnowski into a theory of history which re-enacts conflict as part of its onward progression, but in which reconciliation is the necessary prerequisite for the institution of each new era. This theory influenced his selection of events from Irish history, which become a model for the parallel operation of recurrence in world history. Irish history, therefore, is a sustained level of significance in Finnegans Wake, absorbed into the novel's structure, and providing a wealth of detail to illustrate its thematic concerns. / Thesis / Doctor of Philosophy (PhD)