Mineral magnetic analyses as a means of lithostratigraphic correlation and provenance indication of glacial diamicts: Intra- and interunit variation     

John Walden  John P. Smith  Roger V. Dackombe 《第四纪科学杂志》1992,7(3):257-270

Mineral magnetic analyses are applied to a series of diamict samples taken from the Quaternary sequence in the Isle of Man in order to assess the relative magnitude of the intra-and inter-unit variation of the magnetic properties. The results are analysed both qualitatively and quantitatively and show that the level of intra-unit variation is significantly less than the level of inter-unit variation. The intra-unit variation detected appears to show some relationship to the basic stratigraphy. Previous correlations based upon field evidence of diamict units exposed upon the east and west coasts of the Isle of Man are supported by their mineral magnetic properties. The statistically significant differences in the magnetic mineralogy of the stratigraphically lower Wyllin and Shellag Tills and the upper Orrisdale, Ballavarkish and Ballaquark Tills suggests distinct provenances for these two suites of sediments, allowing potential source areas to be suggested. These source areas are consistent with published data on ice flow directions in the Irish Sea Basin during the Devensian.  相似文献   

TERRAFORMING A CLEAR VIEW     

Alexander G. Smith 《地学学报》1992,4(5):611-612

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The 1984 Round Valley, California Earthquake Sequence     

Keith F. Priestley  Kenneth D. Smith  Robert S. Cockerham 《Geophysical Journal International》1988,95(2):215-235

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First results from the Very Small Array – I. Observational methods     

Robert A. Watson  Pedro Carreira  Kieran Cleary  Rod D. Davies  Richard J. Davis  Clive Dickinson  Keith Grainge †  Carlos M. Gutiérrez  Michael P. Hobson  Michael E. Jones  Rüdiger Kneissl  Anthony Lasenby  Klaus Maisinger  Guy G. Pooley  Rafael Rebolo  José Alberto Rubiño-Martin ‡  Ben Rusholme §  Richard D. E. Saunders  Richard Savage  Paul F. Scott  An&#;e Slosar  Pedro J. Sosa Molina  Angela C. Taylor  David Titterington  Elizabeth Waldram  Althea Wilkinson 《Monthly notices of the Royal Astronomical Society》2003,341(4):1057-1065

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Finite element formulation and algorithms for unsaturated soils. Part I: Theory     

Daichao Sheng  Scott W. Sloan  Antonio Gens  David W. Smith 《国际地质力学数值与分析法杂志》2003,27(9):745-765

This paper presents a complete finite‐element treatment for unsaturated soil problems. A new formulation of general constitutive equations for unsaturated soils is first presented. In the incremental stress–strain equations, the suction or the pore water pressure is treated as a strain variable instead of a stress variable. The global governing equations are derived in terms of displacement and pore water pressure. The discretized governing equations are then solved using an adaptive time‐stepping scheme which automatically adjusts the time‐step size so that the integration error in the displacements and pore pressures lies close to a specified tolerance. The non‐linearity caused by suction‐dependent plastic yielding, suction‐dependent degree of saturation, and saturation‐dependent permeability is treated in a similar way to the elastoplasticity. An explicit stress integration scheme is used to solve the constitutive stress–strain equations at the Gauss point level. The elastoplastic stiffness matrix in the Euler solution is evaluated using the suction as well as the stresses and hardening parameters at the start of the subincrement, while the elastoplastic matrix in the modified Euler solution is evaluated using the suction at the end of the subincrement. In addition, when applying subincrementation, the same rate is applied to all strain components including the suction. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

INGRID: A near-infrared camera for the William Herschel Telescope     

Christopher Packham  Keith L. Thompson  Almudena Zurita  Johan H. Knapen  Ian Smail  Robert Greimel  Daniel F. M. Folha  Chris Benn  rew Humphrey  Rene Rutten  David Ciardi  Matthieu Bec  Richard Bingham  Simon Craig  Kevin Dee  Derek Ives  Paul Jolley  Peter Moore  Marti Pi i Puig  Simon Rees  Gordon Talbot  Sue Worswick 《Monthly notices of the Royal Astronomical Society》2003,345(2):395-405

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Pits and uplifts on Europa     

Richard Greenberg  Martha A Leake  Gregory V Hoppa 《Icarus》2003,161(1):102-126

A survey of depression and uplift features on Europa, based on Galileo regional mapping images, shows that these features come in a wide range of sizes, with numbers increasing greatly with decreasing size, down to the limits of resolution. Size distributions are similar in the northern leading and southern trailing hemispheres, where they are distinctly different from the southern leading and northern trailing hemispheres, suggesting an oblique, antipodal symmetry pattern, similar to that of chaotic and tectonic terrain. This pattern is suggestive of polar wander. Uplifts are usually polygonal or irregular in shape and rarely are cracked. Patches of chaotic terrain, which we had surveyed earlier, are not included in the current study because their topography is generally unclear, and because there is no a priori known genetic linkage with the pits and uplifts.These results contradict generalizations based on the earlier “pits, spots, and domes” (PSD) taxonomy. Most of the type examples for PSDs were simply patches of chaotic terrain selected from a limited portion of their full size range. The use of the term lenticula to collectively describe PSDs is inconsistent with the IAU definition of lenticula: a small dark spot seen at low resolution. Pits and uplifts do not correlate with lenticulae, although chaos often does. Properties of PSDs that have been widely cited as primary evidence for convective upwelling in thick ice (e.g., that uplifts are generally dome-shaped and often cracked; that pits and domes are regularly spaced; that there is a typical diameter of ∼10 km) were premature and not supported by subsequent data. Most pits and uplifts are less than 10 km across so, if they formed by diapirism or convective upwelling, the sources must have been very shallow, less than 5 km deep. How they actually formed remains unknown.  相似文献   

A concept for a superconducting tunnelling junction based spectrograph     

Mark Cropper  M. Barlow  M. A. C. Perryman  Keith Horne  R. Bingham  M. Page  P. Guttridge  A. Smith  A. Peacock  D. Walker  P. Charles 《Monthly notices of the Royal Astronomical Society》2003,344(1):33-44

We describe a multi-order spectrograph concept suitable for 8-m class telescopes, using the intrinsic spectral resolution of superconducting tunnelling junction detectors to sort the spectral orders. The spectrograph works at low orders, 1–5 or 1–6, and provides spectral coverage with a resolving power of   R ≃ 8000  from the atmospheric cut-off at 320 nm to the long-wavelength end of the infrared H or K band at 1800 nm or 2400 nm. We calculate that the spectrograph would provide substantial throughput and wavelength coverage, together with high time resolution and sufficient dynamic range. The concept uses currently available technology, or technologies with short development horizons, restricting the spatial sampling to two linear arrays; however, an upgrade path to provide more spatial sampling is identified. All of the other challenging aspects of the concept – the cryogenics, thermal baffling and magnetic field biasing – are identified as being feasible.  相似文献   

Wilson Harold Maze     

T. Langford‐Smith 《The Australian geographer》1986,17(1)

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THE SPATIO-TEMPORAL SYNCHRONIZATION OF PERIODIC MARKET-PLACES: SIMULATION EXPERIMENTS ON TWO AFRICAN PERIODIC MARKET SYSTEMS     

Alan M. Hay  M.A.  Ph.D.  Robert H.T. Smith  M.A.  Ph.D. 《Singapore journal of tropical geography》1981,2(2):81-90

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