The representer method for data assimilation in single-phase Darcy flow in porous media     

John?BairdEmail author  Clint?Dawson 《Computational Geosciences》2005,9(4):247-271

We apply the representer method, a data assimilation algorithm, to single-phase Darcy flow in porous media. The measurement array that yields the assimilated data can be expressed as a vector of linear functionals of pressure. The a priori discretization errors in the representer method are analyzed in terms of the convergence properties of the underlying numerical schemes used in each part of the algorithm. We formulate some proof-of-concept numerical experiments that illustrate the error analysis.  相似文献   

Microprocessor systems as an aid to estuarine studies in the laboratory     

A.P.M. Lockwood  N.W. Jenkinson  S.R.L. Bolt  M.E. Dawson  A.C. Jensen 《Estuarine, Coastal and Shelf Science》1982,15(2):199-206

Three systems are outlined which indicate the potential of microprocessor systems as control devices in the generation of specifically varying environmental mental conditions. The use of an RCA 1802 Cosmac microprocessor to generate salinity cycles, tidal cycles and temperature cycles is described.  相似文献   

Simplified analysis of offshore piles under cyclic lateral loads     

T.H. Dawson 《Ocean Engineering》1980,7(4):553-562

A simple theory for predicting the response to cyclic lateral loading of piles deeply driven in either soft clay or sand is presented and formulas given for calculating, among other things, deflection and internal bending moment along the pile. The theory assumes the soil resistance to deflection to be characterized by an initial elastic reaction up to a critical deflection level, followed by a yield reaction independent of further deflection. Soil parameters are estimated and the theory is shown to provide good correlation with existing field data.  相似文献   

Two samplers for large-volume collection of chlorinated hydrocarbons     

R. Dawson  J.P. Riley  R.H. Tennant 《Marine Chemistry》1976,4(1):83-88

Two sampling devices for the in situ extraction of chlorinated hydrocarbons from water are described. Both samplers use the macroreticular adsorbent Amberlite XAD-2. They include a “fish” sampler which has been used to collect samples for PCB analysis from waters around the British Isles. Operation of this sampler causes a minimum of interruption to a ship's cruise programme and at the same time allows a large area to be surveyed. The second sampler is a self-powered in situ pump which is cheap to construct and can be left unattended to extract large volumes of water at a fixed station. The device is serviced by divers and samples may be collected daily on a routine sampling basis.  相似文献   

Comparison of the susceptibility of sea trout (Salmo trutta L.) and Atlantic salmon (Salmo salar L.) to sea lice (Lepeophtheirus salmonis (Kroyer, 1837)) infections     

Dawson  L. H. J.; Pike  A. W.; Houlihan  D. F.; McVicar  A. H. 《ICES Journal of Marine Science》1997,54(6):1129-1139

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Lateglacial and Holocene relative sea‐level changes and first evidence for the Storegga tsunami in Sutherland,Scotland          下载免费PDF全文

Antony J. Long  Natasha L. M. Barlow  Sue Dawson  Jon Hill  James B. Innes  Catherine Kelham  Fraser D. Milne  Alastair Dawson 《第四纪科学杂志》2016,31(3):239-255

We reconstruct one of the longest relative sea‐level (RSL) records in north‐west Europe from the north coast of mainland Scotland, using data collected from three sites in Loch Eriboll (Sutherland) that we combine with other studies from the region. Following deglaciation, RSL fell from a Lateglacial highstand of +6?8 m OD (Ordnance Datum = ca. mean sea level) at ca. 15 k cal a BP to below present, then rose to an early Holocene highstand and remained at ca. +1 m OD between ca. 7 and 3 k cal a BP, before falling to present. We find no evidence for significant differential Holocene glacio‐isostatic adjustment between sites on the north‐west (Lochinver, Loch Laxford), north (Loch Eriboll) and north‐east (Wick) coast of mainland Scotland. This suggests that the region was rapidly deglaciated and there was little difference in ice loads across the region. From one site at the head of Loch Eriboll we report the most westerly sedimentary evidence for the early Holocene Storegga tsunami on the Scottish mainland. The presence of the Storegga tsunami in Loch Eriboll is predicted by a tsunami wave model, which suggests that the tsunami impacted the entire north coast of Scotland and probably also the Atlantic coastline of north‐west Scotland.

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A Web-based system enabling the integration,analysis, and 3D sub-surface visualization of groundwater monitoring data and geological models     

Jane Hunter  Charles Brooking  Lucy Reading  Sue Vink 《International Journal of Digital Earth》2016,9(2):197-214

The 3D Water Chemistry Atlas is an intuitive, open source, Web-based system that enables the three-dimensional (3D) sub-surface visualization of ground water monitoring data, overlaid on the local geological model (formation and aquifer strata). This paper firstly describes the results of evaluating existing virtual globe technologies, which led to the decision to use the Cesium open source WebGL Virtual Globe and Map Engine as the underlying platform. Next it describes the backend database and search, filtering, browse and analysis tools that were developed to enable users to interactively explore the groundwater monitoring data and interpret it spatially and temporally relative to the local geological formations and aquifers via the Cesium interface. The result is an integrated 3D visualization system that enables environmental managers and regulators to assess groundwater conditions, identify inconsistencies in the data, manage impacts and risks and make more informed decisions about coal seam gas extraction, waste water extraction, and water reuse.  相似文献   

Modelling impacts of climate change on global food security     

Terence P. Dawson  Anita H. Perryman  Tom M. Osborne 《Climatic change》2016,134(3):429-440

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Cisuralian coals of the Mullaley Sub-basin,northern New South Wales     

M. W. Dawson 《Australian Journal of Earth Sciences》2016,63(3):275-294

The Mullaley Sub-basin of the Gunnedah Basin extends from Quirindi in the southeast, to north of Narrabri, to west of Dunedoo in northern New South Wales. There have been more than 100 boreholes sunk to basement investigating the (lower Permian) Cisuralian coal and coal seam gas resources of the Mullaley Sub-basin since the early 1990s. A desktop review of this open file information has allowed the formal correlation and naming of six Cisuralian coal members attaining a maximum 35 m of cumulative thickness within an upward coarsening sedimentary package totalling no more than 150 m. In ascending order, the coal members are: Bibblewindi (0–10 m), Bohena (3–18 m), Collygra (0.5–3 m), Coxs (1.5–4 m), Tullamullen (0.5–4 m) and Mooki (0.5–3 m).

Cisuralian coal seams in the Maules Creek Formation of the southern Mullaley Sub-basin are here correlated with those of the Greta Coal Measures at Werris Creek and Muswellbrook. It is apparent that basement paleotopography played a significant role in the Cisuralian coal development as coals are best developed where the sedimentary sequence is greater than 60 m thick, as there the thick seams (Bohena and Bibblewindi coal members) occur towards the base of the sequence. The maximum western limit of the Cisuralian coals (Rocky Glen Ridge) is further east than previously inferred with new drilling information showing the Porcupine Formation directly overlying the barren pelletoidal claystones of the Leard Formation or the underlying volcanics (Boggabri Volcanics/Werrie Basalt). Early marine transgressions at the top of the Maules Creek Formation have stopped development of the Mooki, Tullamullen and Coxs coal members in the northern and eastern Mullaley Sub-basin and allowed the development of localised paraconglomerate (diamictite) intervals up to 10 m thick. Thick (>20 m cumulative) coal occurrences are localised to the Jacks Creek and Pilliga East State Forest areas southwest of Narrabri. The coal resource potential of the Mullaley Sub-basin is estimated at 13–28 billion tonnes.  相似文献   

Hector's dolphin movement patterns in response to height and direction of ocean swell     

S Dittmann  S Dawson  W Rayment  T Webster  E Slooten 《新西兰海洋与淡水研究杂志》2016,50(2):228-239

A central question to any understanding of ecology is how animals use their habitat, and how habitat use is influenced by temporally changing features of the environment. Previous research on Hector's dolphins at Akaroa Harbour, New Zealand suggested that dolphins leave inshore, harbour environments during or after rough weather. To test this hypothesis, visual sightings (2000–2012) and acoustic detections (2007–2008) of Hector's dolphins in Akaroa Harbour were modelled to test for a relationship with swell height and swell direction. Sighting rates and acoustic detection rates in Akaroa Harbour were significantly lower on days after big swell events and in some linear models after swell events from the south. These results indicate that swell events influence Hector's dolphin movements in and around Akaroa Harbour. Possible reasons for this behaviour are diverse and need further investigation. However, this information can be used both to predict daily dolphin movement for conservation and research purposes, and to suggest how dolphins may react in future if extreme weather events are becoming frequent.  相似文献