Directional wave measurement at Haifa,Israel, and sediment transport along the Nile littoral cell     

Zev Carmel  Douglas L. Inman  Abraham Golik 《Coastal Engineering》1985,9(1):21-36

Results of three years of directional wave measurement at the Eastern Mediterranean coast of Haifa, Israel are presented. The wave-height and energy-flux distributions reveal a moderately high-energy coast with a bimodal annual cycle.The rate of wave-induced longshore sediment transport is estimated from the directional energy flux distributions. It describes an annual cycle with a maximum northward transport of 75 ± 14 × 10³ m³/month in midwinter and a southward transport of 26 ± 5 × 10³ m³/month in summer. The net annual transport is northward and computed at 110 ± 100 × 10³ m³/yr.We show that a wave-induced transport is sufficient in explaining the apparent transport of sediments in the Nile Littoral Cell, from the Nile Delta source to the Haifa Bay sink.  相似文献   

A laboratory test of the soil chemical submodels of two models of catchment acidification     

Ian C. Grieve 《水文研究》1989,3(4):339-346

Parameters for ion exchange selectivity and aluminium hydroxide dissolution in the soil chemical submodels used in applications of the Birkenes model and of MAGIC are compared and several discrepancies identified for organic soils. A laboratory column simulation of the soil chemical submodels is proposed and applied to soils from the Loch Dee area in Galloway. Experimental results were well predicted by a simplified version of MAGIC, with ion exchange selectivity parameters similar to those used in a previous simulation of one subcatchment of Loch Dee. The aluminium hydroxide dissolution parameter used previously was found to be too low for the organic soil materials, where a value of 106 predicted the experimental results more closely. The model developed also included a simple silicate weathering reaction to release base cations into the system. It is concluded that such simple laboratory simulations are useful for independent calibration of the soil chemical submodel of catchment models.  相似文献   

On determining the cluster abundance normalization     

Elena Pierpaoli  Stefano Borgani  Douglas Scott  Martin White 《Monthly notices of the Royal Astronomical Society》2003,342(1):163-175

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Optimal Compensation and Implementation for Adaptive Optics Systems     

Douglas P. Looze  Markus Kasper  Stefan Hippler  Orhan Beker  Robert Weiss 《Experimental Astronomy》2003,15(2):67-88

This paper develops a compensation algorithm based on Linear–Quadratic–Gaussian (LQG) control system design whose parameters are determined (in part) by a model of the atmosphere. The model for the atmosphere is based on the open-loop statistics of the atmosphere as observed by the wavefront sensor, and is identified from these using an auto-regressive, moving average (ARMA) model. The (LQG) control design is compared with an existing compensation algorithm for a simulation developed at ESO that represents the operation of MACAO adaptive optics system on the 8.2 m telescopes at Paranal, Chile. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

An HST morphological survey of faint extremely red objects     

David G. Gilbank  Ian Smail  R. J. Ivison  C. Packham 《Monthly notices of the Royal Astronomical Society》2003,346(4):1125-1142

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Quaternary stratigraphy of the buried valleys of the lower Red Deer River,Alberta, Canada     

David J. A. Evans  Ian A. Campbell 《第四纪科学杂志》1995,10(2):123-148

The Quaternary fills of the buried valleys of southern Alberta and Saskatchewan have provided a wealth of information for the reconstruction of the glacial-interglacial record of the western plains of Canada, and this paper reports on the previously unstudied stratigraphy of the buried Calgary Valley and its former tributaries in the lower Red Deer River area. We attempt to differentiate Empress Group sediments, which potentially relate to pre-glacial, interglacial/ interstadial and post-glacial lake and river deposition, using sedimentology, stratigraphy and palaeoecology. Twenty-nine stratigraphical logs indicate that Empress Group sediments have infilled a considerably large area of badlands and tributary coulees that once drained into the Calgary Valley, located 15 km to the north of Dinosaur Provincial Park. Radiocarbon dates of 52.4 ka, 27.4 ka and > 42.4 ka and glacially modified quartz grains suggest that at least some of the valley fills date to interglacial or interstadial periods and may be mid-Wisconsinan in age. However, outcrops of an older till overlying other valley fills suggest that the buried valleys were only partially excavated during interglacials/interstadials and that older (even pre-glacial) sediments could have survived. Subglacial channels, recognisable on air photographs, largely coincide with buried valley positions due to the preferential excavation of the Quaternary sediment by meltwater and are filled with post-glacial lake sediment from which a radiocarbon date of 16 ka BP was obtained. Pre-glacial and glacial/post-glacial Empress Group sediments are lithologically indistinct but cover a large time span in southern Alberta.  相似文献   

Numerical simulations of weak lensing measurements     

David J. Bacon  Alexandre Refregier  Douglas Clowe  Richard S. Ellis 《Monthly notices of the Royal Astronomical Society》2001,325(3):1065-1074

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Analysis of a “flickering” Geminid fireball     

Martin BEECH  Alison ILLINGWORTH  Ian S. MURRAY 《Meteoritics & planetary science》2003,38(7):1045-1051

Abstract— In the early morning hours of December 13, 2002, a bright Geminid fireball with an absolute magnitude of ?9.2 ± 0.5 was observed from Southern Saskatchewan, Canada. The fireball displayed distinct small‐scale oscillations in brightness, or flickering, indicative of the parent meteoroid being both non‐spherical and rotating. Using the light curve derived from a calibrated radiometer, we determine a photometric mass of 0.429 ± 0.15 kg for the meteoroid, and we estimate from its initial rotation rate of some 6 Hz that the meteoroid was ejected from the parent body (3200) Phaethon some 2500 ± 500 years ago. We find that 70% of Geminid fireballs brighter than magnitude ?3 display distinct flickering effects, a value that is in stark contrast to the 18% flickering rate exhibited by sporadic fireballs. The high coincidence of flickering and the deep atmospheric penetration of Geminid fireballs are suggestive of Geminid meteoroids having a highly resilient structure, a consequence, we suggest, of their having suffered a high degree of thermal processing. The possibility of Gemind material surviving atmospheric ablation and being sampled is briefly discussed, but the likelihood of collecting and identifying any such material is admittedly very small.  相似文献   

The cluster wind from local massive star clusters     

Ian R. Stevens  Joanna M. Hartwell 《Monthly notices of the Royal Astronomical Society》2003,339(1):280-288

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The clustering of halo mergers     

Will J. Percival&#;  Douglas Scott  John A. Peacock  James S. Dunlop 《Monthly notices of the Royal Astronomical Society》2003,338(4):L31-L35

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