Statistical convective down motion driven by random inputs of localized buoyancy in a homogeneous sea

A model for the dynamics of dense water plumes in a homogeneous sea initially at rest, suddenly perturbed on the air-sea surface by a series of random buoyancy inputs localized on small space and time scales, is presented here. A Lagrangian representation allows the time evolution for a single, mixing plume able to carry down dense water mass to be obtained. Moreover scaling laws are found for long times, which depend on the surface air-sea interaction statistics involved and on the forcing time scale: in this way it is shown that the asymptotic time evolution of the plumes is the result of surface heterogeneous buoyancy forcing inputs

Developing system models to help Great Britain's railways embrace innovative technologies with confidence

Railways are under pressure to become more efficient and cut their costs; innovation has a part to play in achieving these goals. The railway is, however, a complex and closely coupled system, making it difficult in the early stages of development, to be clear what the system-wide impact of innovation will be. The research covered in this paper stems from the idea that computer-based models of existing systems can help overcome this problem, by providing a baseline framework against which the impact of innovation can be identified. The paper describes development of a repeatable modelling methodology, which elicits\ud objective system data from Railway Group Standards and integrates it using CORE®, a powerful system modelling tool, to create system models. The ability of such models to help identify impacts is verified, using as an example the introduction of RailBAM (a new technology that acoustically monitors the health of rolling stock axle bearings) into the existing hot axle bearing detection system

The railways and the war effort, 1914 - 1915

No Abstrac

WILHELM GRÜTTER: A name among seafaring men

(A history of the training ship 'General Botha'). Cape Town, 1973, pp 173. Until recently, the South African Navy could claim the dubious distinction that of all three arms of the Defence Force, its history was the least adequately chronicled. At last the unfavourable balance has been redressed through the publication of two excellent books, that under review being the second to appeal'.Keywords:  General Botha; training ship; South African Navy; Defence Force; HMS Thames; Naval Cadet Corp

SEM petrography of samples of the Lias Group of England and Wales

This report summarises work undertaken in support of the Ground Movements: Shrink/Swell Project. It provides petrographical descriptions acquired using scanning electron microscopy (SEM) of a suite of samples (predominantly mudrocks) from the main Lias Group depositional basins across England and Wales. The main Formations sampled are the Scunthorpe Mudstone (n = 5), the Blue Lias (n = 8), the Charmouth Mudstone (n = 21 including 15 samples from weathering profiles), the Marlstone Rock (n = 4), and the Whitby Mudstone (n = 5). Small numbers of samples from the other Lias Formations are also described. The analyses largely confirm the observations made by earlier workers, and are broadly consistent with the results of XRD analyses. The Scunthorpe Mudstone Formation samples are typically laminated with mineralogies probably dominated by illite and/or smectite (although XRD analysis would be required to confirm this). Very finely crystalline gypsum/anhydrite occurs throughout. A sample from the Barnstone Limestone Member is typical, dominated by fine grained calcite, with minor dolomite and clay. A sample from the Frodingham Ironstone Member is also typical being a goethitic oolitic ironstone. The Blue Lias Formation samples are typically massive, hard, dense, highly calcareous mudrocks. Some less calcareous samples preserve lamination, and minor framboidal and euhedral pyrite is present. SEM analysis confirms that variations in surface area (Appendix Table 1.1) broadly correspond to variations in the relative proportions of carbonate and clay, with variations matching a regional trend in calcite content reported by Kemp and Mc Kervey (2001). Clay mineral assemblages in the two southernmost samples from this formation contain major illite, with minor kaolinite, chlorite and illite/smectite, whereas in the samples from further north, illite tends to be less dominant of the clay mineral assemblage and smectite and/or illitesmectite become more significant, suggesting either a difference in the primary makeup of the sediment, or that the smectite to illite transformation is more advanced in the most southernmost samples. The Charmouth Mudstone Formation is characterised by well-laminated mudrocks with only minor amounts of silt and sand-grade material. EDXA analysis suggests a predominance of Kbearing (illitic) clays, although XRD indicates that the clay mineral assemblages comprise major kaolinite, with minor illite, chlorite and possible illite-smectite, with minor smectite also present in the samples from the Worcester basin. Samples of this formation from the Dorset Coast contain well-developed calcite veining, with cone-in-cone (beef) fabrics present. Gypsum/anhydrite is locally developed along lamination surfaces and early framboidal pyrite is present. The samples from weathering profiles at Dimmer and Blockley reveal development of locally abundant gypsum/anhydrite, nodularisation, rootleting and oxidation towards the surface as seen in hand specimen, but these features are poorly defined on the scale of SEM stubs. No appreciable, systematic differences clay mineralogy is noted through the weathering profiles. The Marlstone Rock Formation is peloidal/ooidal with thick coatings of probable chloritic or glauconitic clay on well-rounded grains in a fine clay matrix. Cone-in-cone calcite cement is locally present. The Whitby Mudstone Formation is confirmed as a typically well-laminated mudrock with minor silty material. EDXA suggests a predominance of illite and/or illite-smectite (K and KCa-bearing) compositions, consistent with earlier, quantitative, XRD data on samples from the Cleveland Basin by Kemp and Mc Kervey (2001) which indicates that the smectite to illite transformation is well advanced. Qualitative XRD on these samples indicates major kaolinite with minor illite, illite-smectite and chlorite

Statistical convective down motion driven by random inputs of localized buoyancy in a homogeneous sea

A model for the dynamics of dense water plumes in a homogeneous sea initially at rest, suddenly perturbed on the air-sea surface by a series of random buoyancy inputs localized on small space and time scales, is presented here. A Lagrangian representation allows the time evolution for a single, mixing plume able to carry down dense water mass to be obtained. Moreover scaling laws are found for long times, which depend on the surface air-sea interaction statistics involved and on the forcing time scale: in this way it is shown that the asymptotic time evolution of the plumes is the result of surface heterogeneous buoyancy forcing inputs

B. N. RECKITT: The Lindley Affair. A Diary of the Boer War

On May 31, 1900, the 13th Battalion Imperial Yeomanry surrendered to General Piet de Wet at Lindley in the north-eastern Free State.The author has here published the diary of his father, a trooper involved in the 'Lindley Affair: and supplemented it with outlines of the causes and course of the Second Anglo- Boer War, along with three chapters examining the encounter from both sides and critically evaluating the episode with a view to determining responsibility for the surrender. The well-written diary, although dealing with a relatively insignificant encounter, has merit in its detailed exposition of life in the 13th during the six days of fighting which preceded the surrender. One receives an admirably clear picture of activities both in the command sector and amongst the men.Keywords: 13th Battalion Imperial Yeomanry; General Piet de Wet; Lindley; north-eastern Free State; Second Anglo- Boer Wa

SEM petrography of samples of the London Clay of Southern England

This report summarises work undertaken in support of the Ground Movements: Shrink/Swell Project undertaken as part of the BGS Physical hazards Programme. It provides petrographical descriptions acquired using scanning electron microscopy (SEM) of a suite of samples (n = 24, from 19 sites) collected from the London Clay of the London and Hampshire Basins in southern England. The analysis indicates that the samples from both basins display considerable variations in grain size both on a millimetric scale (mm-scale laminae of clay-rich, or silt-rich or fine-sand material), and also on a regional scale, with a broad trend to increasing grain size and decreasing clay-content from NE to SW. The clay content of a given mudstone is likely to be an important factor in governing the shrinking and swelling capacity of the London Clay at a given site – clearly if clay is volumetrically of minor significance within the sediment, then it will have proportionally less impact on sediment volume as it shrinks/swells, irrespective of it’s mineralogy. As might be anticipated, porosities, and hence permeabilities, will be higher where grain sizes are coarser, this will affect the susceptibility of the lithology at a given site to wetting/drying. It is recommended that a more quantitative assessment of sediment grain size is carried out. X-ray microchemical analyses qualitatively confirm the results of XRD analysis (Kemp and Wagner 2006), indicating that the clays are dominated by illite and smectite species, which might be expected to undergo significant shrinking and swelling in response to wetting and drying

Models of dolomitisation : a literature review

From an economic perspective (e.g. in the hydrocarbon and groundwater industries) one of the main questions relating to dolomitisation is the influence the dolomitisation process has on the nature of the dolomitised limestone’s pore system. To this end, one of the key objectives of the “Development of Integrated Methods for Characterising Faults and Fractures in Reservoirs and Aquifers” project is to understand the nature and distribution of pore-systems within dolomitised limestones and in particular to understand the influence of fractures on dolomitisation and/or porosity distribution, and subsequent fluid-flow pathways. This document provides a literature review on the current state of knowledge regarding the dolomitisation process. The “dolomite problem” is introduced, and the kinetic inhibitions on dolomitisation from seawater, which ultimately form the crux of the dolomite problem are summarised. Over the years, various models have been suggested in order to explain the dolomitisation process. Systematic summaries of these models are presented. In essence, each model attempts to provide a mechanism by which the kinetic inhibitions to dolomite formation are overcome (typically through evaporation or dilution of seawater), and a means of pumping large porevolumes of fluid through the body undergoing dolomitisation. Following the summaries of the dolomitisation models, the next section contains an introduction into the classification of dolomite fabrics and pore systems. The final sections outline the regional geology of the Lower Carboniferous in the Midlands of the United Kingdom, and describes potential analogue material in Derbyshire and the Bowland Basin