Unsteady wake modelling for tidal current turbines

The authors present a numerical model for three-dimensional unsteady wake calculations for tidal turbines. Since wakes are characterised by the shedding of a vortex sheet from the rotor blades, the model is based on the vorticity transport equations. A vortex sheet may be considered a jump contact discontinuity in tangential velocity with, in inviscid hydrodynamic terms, certain kinematic and dynamic conditions across the sheet. The kinematic condition is that the sheet is a stream surface with zero normal fluid velocity; the dynamic condition is that the pressure is equal on either side of the sheet. The dynamic condition is explicitly satisfied at the trailing edge only, via an approximation of the Kutta condition. The shed vorticity is the span-wise derivative of bound circulation, and the trailed vorticity is the time derivative of bound circulation, and is convected downstream from the rotors using a finite-volume solution of vorticity transport equations thus satisfying the kinematic conditions. Owing to an absence in the literature of pressure data for marine turbines, results from the code are presented for the NREL-UAE Phase IV turbine. Axial flow cases show a close match in pressure coefficients at various spanwise stations; however, yawed flow cases demonstrate the shortcomings of a modelling strategy lacking viscosity

Trace Analysis Using Laser Ablation Initiated Resonant Ionisation Mass Spectrometry

This thesis deals with the practical aspects of the development and use of a resonant ionisation mass spectrometer. The first chapter gives an outline of the ideas and the applications of resonant ionisation mass spectrometry (RIMS), together with a brief historical overview of the method, showing its development in the last twenty years. The second chapter deals with the theoretical aspects of resonant ionisation spectroscopy (RIS). Firstly time dependent perturbation theory is used to demonstrate how the selectivity and sensitivity of the method come about. Next the derivation of rate equations for a simple system, a practical way of analysing RIMS ion yields, is shown. Causes of broadening of transitions are then described. Non-linear optics and the theoretical aspects of laser ablation are then discussed. Chapter 3 deals with the instrumentation and describes the equipment used. The mass spectrometer was designed and assembled in Glasgow and constructed by Kratos Analytical. This chapter details the improvements that have been made to the original design. Further enhancements that are possible but not implemented are given in chapter 8. Chapter 4 describes the development of the computer software. This software is used to control the data acquisition hardware and for subsequent analysis of the data. The software was written exclusively by the author. Chapter 5 presents some of the earlier results from the instrument. The author, together with Dr Mike Towrie and Dr Adrian Land, was responsible for the acquisition of these results Chapter 6 examines in detail the laser ablation process. Laser ablation is used to evaporate samples to produce a flux of neutrals leaving the surface. It is the primary evaporation source used at Glasgow and it is very poorly understood, both in terms of underlying theory and some phenomenological aspects of it. For the optimal operation of the instrument the process of neutral production must be well characterised. The calcium ablation work presented was performed by the author, Dr M Towrie and Dr A Land. The gold and lead ablation work was the exclusive work of the author. The work on aluminium and NIST steel was performed by Mr I Borthwick and the author. Chapter 7 presents work on trace analysis of gold using RIMS. This work involves the detection of trace amounts of gold in a copper matrix. Other resonant schemes will be discussed. All work in this chapter is the sole work of the author. Chapter 8 gives conclusions about the viability of the RIMS method in the field of trace analysis, together with a discussion of possible improvements in the instrument and the methodology. Appendix A contains information on the physical characteristics of gold. Appendix B gives details of field inverting optics which were designed by the author. A design of this type is expected to improve the performance of the instrument described in this thesis

Corporate social responsibility: The disclosure-performance gap

As increased stakeholder pressure requires companies to be transparent about their CSR practices, it is essential to know how reliable corporate disclosure mechanisms are, testing the gap between corporate social responsibility claims and actual practice. This study benchmarks corporate social responsibility policies and practices of ten international hotel groups of particular importance to the European leisure market. We found that corporate systems are not necessarily reflective of actual operations, environmental performance is eco-savings driven, labour policies aim to comply with local legislation, socio-economic policies are inward looking with little acceptance of impacts on the destination, and customer engagement is limited. Generally larger hotel groups have more comprehensive policies but also greater gaps in implementation, while the smaller hotel groups focus only on environmental management and deliver what they promised. As the first survey of its kind in tourism, both the methodology and the findings have implications for further research. © 2012 Elsevier Ltd

A randomised controlled trial to explore attitudes to routine scale and polish and compare manual versus ultrasonic scaling in the general dental service in Scotland [ISRCTN99609795]

BACKGROUND: To investigate, within general dental practice, patients' and vocational dental practitioners' (VDP) attitudes towards the benefits and costs of a simple scale and polish and to compare the experience of using manual versus ultrasonic instruments to scale teeth. METHODS: 28 VDPs and 420 patients participated. Patients were randomly allocated to either group. Patients' and VDPs' attitudes towards, and experience of, the scale and polish were elicited by means of self-administered questionnaires. RESULTS: The majority of patients (99%) believed a scale and polish was beneficial. VDPs considered ultrasonic treatment to be appropriate on significantly more occasions than they did for manual scale and polish (P < 0.001). Patient discomfort: with ultrasonic scaling 69.2% felt 'a little uncomfortable' or worse compared with 60% of those undergoing manual treatment (P = 0.072). VDPs considered treatment charges were appropriate for 77% of patients. CONCLUSION: Routine scaling and polishing is considered beneficial by both patients and vocational trainees. The majority of patients, regardless of treatment method, experience some degree of discomfort when undergoing a scale and polish. VDPs showed a preference for the ultrasonic treatment method

IQuaD dental trial; improving the quality of dentistry : a multicentre randomised controlled trial comparing oral hygiene advice and periodontal instrumentation for the prevention and management of periodontal disease in dentate adults attending dental primary care

Peer reviewedPublisher PD

Putting social impact assessment to the test as a method for implementing responsible tourism practice

The discourse on the social impacts of tourism needs to shift from the current descriptive critique of tourism to considering what can be done in actual practice to embed the management of tourism's social impacts into the existing planning, product development and operational processes of tourism businesses. A pragmatic approach for designing research methodologies, social management systems and initial actions, which is shaped by the real world operational constraints and existing systems used in the tourism industry, is needed. Our pilot study with a small Bulgarian travel company put social impact assessment (SIA) to the test to see if it could provide this desired approach and assist in implementing responsible tourism development practice, especially in small tourism businesses. Our findings showed that our adapted SIA method has value as a practical method for embedding a responsible tourism approach. While there were some challenges, SIA proved to be effective in assisting the staff of our test case tourism business to better understand their social impacts on their local communities and to identify actions to take

An unsteady hydrodynamic model for tidal current turbines

Due to concerns about the impacts of carbon emissions on the environment, the security of supply of electricity and the likelihood of achieving “peak-oil” in the near future, governments have legislated to reduce reliance on fossil fuels. An attractive alternative is power obtained from tidal currents, and the coast of the British Isles is especially hydraulically active. Tidal energy converters typically resemble wind turbines however, unlike wind turbines, they are expected to operate in an environment which is singularly hostile, and will also be expected to generate power in non-ideal operating conditions. This thesis is concerned with the ability to model individual and groups of tidal devices including their mutual interactions. The ability to capture unsteady inflow conditions at realistic array spacing requires preservation of turbine wakes over a sufficiently large range at spatial resolutions and over time durations which are not feasible using standard computational fluid dynamics software. This thesis has combined methodologies developed for helicopter wake modelling with techniques used in naval architecture for modelling thick maritime propellers into a computational tool. The particular formulation of the Navier-Stokes equations employed allows the determination of the unsteady pressure and force distributions on a turbine rotor due to the effects of a neighbouring device, even if it is operating some significant distance upstream. The constituents of the method of this thesis are developed and applied to “proof-of principle” studies. These include flow past static and oscillating 2-D aerofoils and past a 3-D wing, wind turbine and tidal turbine configuration. The results from these studies demonstrate that the model is convergent and capable of capturing the time dependant forces on these devices, and by comparison with analytical or experimental results, or via inter-model comparison begins the process of calibration and validation of the model. The method is then applied to flow past groups of turbines in various array configurations, and a coaxial, contra-rotating device. The outcome of this work is a decision making tool which can be used to improve success and reduce risk in tidal power array planning, optimise device configurations and is translatable back into rotorcraft or naval architecture usage