The Energetic Implications of Using Deforming Reference Descriptions to Simulate the Motion of Incompressible, Newtonian Fluids

In this work the issue of whether key energetic properties (nonlinear, exponential-type dissipation in the abscence of forcing and long-term stability under conditions of time dependent loading) are automatically inherited by deforming reference descriptions is resolved. These properties are intrinsic to real flows and the conventional Navier-Stokes equations. A completely general reference description of an incompressible, Newtonian fluid, which reconciles the differences between opposing schools of thought in the literature is derived for the purposes of this investigation. The work subsequently focusses on establishing a class of time discretisations which inherit these self-same energetic properties, irrespective of the time increment employed. The findings of this analysis have profound consequences for the use of certain classes of finite difference schemes in the context of deforming references. It is significant that many algorithms presently in use do not automatically inherit the fundamental qualitative features of the dynamics. An `updated' approach as a means of avoiding ever burgeoning deformation gradients and a still further simplified implementation are further topics explored.Comment: 26 pages, 2 figures, lemma 2 proof correcte

The Vale of Pickering : an initial summary of the Quaternary/superficial geology and data holdings

The British Geological Survey (BGS), together with a number of partners is undertaking an independent environmental monitoring programme to characterise baseline conditions across the Vale of Pickering in North Yorkshire, in the vicinity of a site close to Kirby Misperton (Third Energy, KM8) proposed for shale-gas exploration and production. The monitoring will include measurement of: water quality (groundwater and surface water), seismicity, ground motion, air quality including radon, and soil gas. The programme aims to establish the environmental baseline before any shale-gas explorations begin. This report presents the results of a desk study to develop an initial summary of the Quaternary superficial geology across the Vale of Pickering. It is a component and specific deliverable of the environmental baseline project. The Quaternary deposits form a shallow aquifer that is used locally for drinking water supply and agriculture. A separate report considers the bedrock geology. The geological information in this report will be used to identify aquifer dimensions and configurations, groundwater flow paths and potential contaminant migration pathways, as well as determining optimum locations for sampling and monitoring. It will also provide information to support the locating of new borehole infrastructure (suitable for groundwater sampling and seismometers) and will underpin the interpretation of acquired hydrogeochemical data

Construction management contracts: law and practice

The context of construction management (CM) reveals that this method of procurement is as much a management philosophy as a contract structure. It is important to consider legal and contractual issues in this context. The interplay between management and law is complex and often misunderstood. Before considering specific issues, the use of contractual remedies in business agreements is discussed. In addition, the extent to which standardising a form of contract detracts or contributes to the success of projects is also considered. The dearth of judicial decisions, and the lack of a standard form, render it difficult to be specific about legal issues. Therefore, the main discussion of legal issues is centred around a recently completed research project which involved eliciting the views of a cross-section of experienced construction management clients, consultants and trade contractors. These interviews are used as the basis for highlighting some of the most important legal points to consider when setting up CM projects. The interviews revealed that the advantage of CM is the proximity of the client to the trade contractors and the disadvantage is that it depends on a high degree of professionalism and experience; qualities which are unfortunately difficult to find in the UK construction industry

A 3D geological model of the superficial deposits in the Selby area

The Selby 3D geological model, commissioned by the Environment Agency, covers an area of 1,300km2 and shows the distribution and thickness of superficial deposits between Thorne, just north of Doncaster, to Haxby, just north of York. Surfaces derived from this model will be used by the Environment Agency to construct a numerical, spatially distributed model of recharge to the underlying regionally important Sherwood Sandstone Group aquifer and to update their existing numerical regional groundwater model. This report describes the geological units modelled, the 3D modelling methodology used and the limitations of the model

The response of the magnetosphere to the passage of a coronal mass ejection on March 20-21 1990

International audienceThe geomagnetic response to the passage of a coronal mass ejection (CME) is studied. The passage of the CME resulted in a storm sudden commencement (SSC) at 2243 UT on March 20 1990 with disturbed magnetic activity during the following 24 h. The auroral, sub-auroral and equatorial magnetic response to the southward turning at 1314 (±5) UT on March 21 and the equatorial response to the southward turning associated with the SSC on 20 March are discussed in terms of existing models. It is found that the auroral and sub-auroral response to the southward turning associated with the SSC is a factor 2 or more quicker than normal due to the shock in the solar wind dynamic pressure. The low-latitude response time to the southward turning, characterised by Dst and the magnetopause current corrected Dst*, is unaffected by the shock. Dst and Dst*, characteristic of the equatorial magnetic field, responded to the 1314 (±5) UT southward turning prior to the first observed substorm expansion phase onset, suggesting that a dayside loading process was responsible for the initial enhancement in the ring current rather than nightside particle injection. The response time of the auroral and sub-auroral magnetic field to the southward turning at 1314 (±5) UT on March 21 is measured at a variety of longitudes and latitudes. The azimuthal propagation velocity of the response to the southward turning varied considerably with latitude, ranging from ~8 km s?1 at 67°N to ~4 km s?1 at 55°N. The southward velocity of the equatorward boundary of the northern polar convection pattern has been measured. This velocity was ~1.2 km s?1 at 1600 MLT, although there was evidence that this may vary at different local times

Hydrogen sorption properties of magnesium-based thin films

Magnesium hydride is a promising material for hydrogen storage. However, the thermodynamic stability of the hydride coupled with slow reaction kinetics means that it is currently infeasible for application as mobile hydrogen storage media. Thin films of magnesium have been investigated to ascertain the influence of stress on the effects of the sorption thermodynamics and kinetics. It was found that: • The intrinsic stress state can be heavily influenced by deposition conditions. • The influence of the underlying microstructure heavily influences hydrogen sorption mechanics. A model has been proposed which shows regimes dominated by porosity, elastic and plastic contributions and their likely effects on sorption thermodynamics. • Stress analysis using different film thicknesses has been used to model the diffusion behaviour within the films, demonstrating how differential rates and directionality of absorption also affect both kinetic and thermodynamic properties of the films. • A novel approach to tailor thin film stress using flexible substrates was used to investigate and tune thermodynamics. The use of an opto-mechanical hydrogen sensor based on this system design. • Y/Mg multilayer systems were investigated for the first time. The characterisation of these shows that hcp/fcc yttrium occurs at different layer thicknesses, altering the lattice spacings at coherent interfaces with Mg