A search for variable stars in the globular cluster M3     

Kaluzny  Hilditch  Clement  & Rucinski 《Monthly notices of the Royal Astronomical Society》1998,296(2):347-358

We describe here the results of a photometric time-sequence survey of the globular cluster M3 (NGC 5272), in a search for contact and detached eclipsing binary stars. We have discovered only one likely eclipsing binary and one SX Phe-type star in spite of monitoring 4077 stars with V  < 20.0 and observing 25 blue straggler stars (BSS). The newly identified SX Phe star, V237, shows a light curve with a variable amplitude. Variable V238 shows variability either with a period of 0.49 d or with a period of 0.25 d. On the cluster colour–magnitude diagram, the variable occupies a position a few hundredths of a magnitude to the blue of the base of the red giant branch. V238 is a likely descendant of a binary blue straggler.   As a side result we obtained high-quality data for 42 of the previously known RR Lyrae variables, including 33 of Bailey type ab, seven type c and two double-mode pulsators. We used equations that relate the physical properties of RRc stars to their pulsation periods and Fourier parameters in order to derive masses, luminosities, temperatures and helium parameters for five of the RRc stars. We also tested equations that relate the [Fe/H], M _V and temperature of RRab stars to pulsation period and Fourier parameters. We derived [Fe/H]= −1.42 in good agreement with spectroscopic determinations.  相似文献   

DISCUSSION OF "Ground-Water Pollution of the Madras Urban Aquifer, India," by M. V. Somasundaram, G. Ravindran, and J. H. Tellam     

Thangadurai P. Clement 《Ground water》1993,31(6):1029-1029

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Field studies of anoxic conditions in the Baltic Sea during the cruise of R/V <Emphasis Type="Italic">Professor Albrecht Penck</Emphasis> in July 2006     

G. Jost  B. Clement  S. V. Pakhomova  E. V. Yakushev 《Oceanology》2007,47(4):590-593

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Tilting of active folds and drainage asymmetry on the Manawatu anticlines,New Zealand: a preliminary investigation   总被引：1，自引：0，他引：1  

Alastair J. H. Clement  Martin S. Brook 《地球表面变化过程与地形》2008,33(11):1787-1795

The apparent southward tilting of five anticlines in the Manawatu, North Island, New Zealand, is investigated using two drainage basin analysis techniques: the transverse topographic symmetry factor (T) and the asymmetry factor (AF). The techniques are used to determine whether westward‐flowing trunk streams on the gentle western limbs of five anticlines are migrating southwards across their drainage basins, concomitant with down‐tilting of the fold axes. While results show potential for the techniques to be applied in such a tectonic setting, our findings are inconclusive. This could be due to the incipient nature of the folds (c. 0·5 Ma in age), and it would seem more appropriate to apply the techniques in concert with detailed field analyses of river migration patterns. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Ground Penetrating Radar Imaging of an Aquifer During a Pumping Test   总被引：3，自引：0，他引：3  

Anthony L. Endres  William P. Clement  David L. Rudolph 《Ground water》2000,38(4):566-576

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Direct simulations of the stress redistribution in the scaling organization of fracture tectonics (SOFT) model     

C. Narteau  P. Shebalin  M. Holschneider  J.-L. Le Mouël  & C.J. Allègre 《Geophysical Journal International》2000,141(1):115-135

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Analytical model for computing residence times near a pumping well   总被引：4，自引：2，他引：2  

Simpson MJ  Clement TP  Yeomans FE 《Ground water》2003,41(3):351-354

An analytical solution for calculating the residence time of fluid flowing toward a pumping well in an unconfined aquifer has been developed. The analytical solution was derived based on a radial, steady-state, Dupuit-Forchheimer flow model. The resulting integral expression involved computing the imaginary error function, for which a simple series expansion is proposed. The validity of the analytical expression is demonstrated by testing its results against numerical results for an example problem. The analytical solution compared favorably with the numerical approximation.  相似文献   

Quality analysis applied on eddy covariance measurements at complex forest sites using footprint modelling   总被引：7，自引：0，他引：7  

C. Rebmann  M. Göckede  T. Foken  M. Aubinet  M. Aurela  P. Berbigier  C. Bernhofer  N. Buchmann  A. Carrara  A. Cescatti  R. Ceulemans  R. Clement  J. A. Elbers  A. Granier  T. Grünwald  D. Guyon  K. Havránková  B. Heinesch  A. Knohl  T. Laurila  B. Longdoz  B. Marcolla  T. Markkanen  F. Miglietta  J. Moncrieff  L. Montagnani  E. Moors  M. Nardino  J.-M. Ourcival  S. Rambal  Ü. Rannik  E. Rotenberg  P. Sedlak  G. Unterhuber  T. Vesala  D. Yakir 《Theoretical and Applied Climatology》2005,80(2-4):121-141

Summary Measuring turbulent fluxes with the eddy covariance method has become a widely accepted and powerful tool for the determination of long term data sets for the exchange of momentum, sensible and latent heat, and trace gases such as CO₂ between the atmosphere and the underlying surface. Several flux networks developed continuous measurements above complex terrain, e.g. AmeriFlux and EUROFLUX, with a strong focus on the net exchange of CO₂ between the atmosphere and the underlying surface. Under many conditions basic assumptions for the eddy covariance method in its simplified form, such as stationarity of the flow, homogeneity of the surface and fully developed turbulence of the flow field, are not fulfilled. To deal with non-ideal conditions which are common at many FLUXNET sites, quality tests have been developed to check if these basic theoretical assumptions are valid.In the framework of the CARBOEUROFLUX project, we combined quality tests described by Foken and Wichura (1996) with the analytical footprint model of Schmid (1997). The aim was to identify suitable wind sectors and meteorological conditions for flux measurements. These tools were used on data of 18 participating sites. Quality tests were applied on the fluxes of momentum, sensible and latent heat, and on the CO₂-flux, respectively. The influence of the topography on the vertical wind component was also checked. At many sites the land use around the flux towers is not homogeneous or the fetch may not be large enough. So the relative contribution of the land use type intended to be measured was also investigated. Thus the developed tool allows comparative investigations of the measured turbulent fluxes at different sites if using the same technique and algorithms for the determination of the fluxes as well as analyses of potential problems caused by influences of the surrounding land use patterns.  相似文献   

The Spectral Determination of Depths to Buried Magnetic Basement Rocks     

S. Treitel  W. G. Clement  R. K. Kaul 《Geophysical Journal International》1971,24(4):415-428

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Asthenospheric counterflow: a kinematic model     

Clement G. Chase 《Geophysical Journal International》1979,56(1):1-18

Summary. Present-day plate motions imply that about 240 km³ of oceanic lithosphere is created by sea-floor spreading and destroyed by subduction per year. A greater volume of asthenosphere will be dragged along by plate motions. Given the fluxes generated at plate boundaries, the horizontal direction and net rate of counterflow required to maintain mass balance is determined globally by a simple analytical model. Time-dependent calculations indicate that the motions are approximately valid in the hotspot reference frame over the past 5 Myr. Under most plates, the model return flow is opposite to the lithospheric motion in the hotspot frame. The counterflow dominates the resisting stresses to plate motion, so driving force models based on plate drag alone are not valid where the directions of plate motion and counterflow differ. The most marked departure of the two directions is under the North American plate. The model counterflow directions indicate that the sources of mantle hotspots are not located within the asthenosphere. Model flux balances demonstrate exchange of material between asthenospheric reservoirs located beneath different plates. Suggestions of southward asthenospheric motion under the North Atlantic, based on physical features around Iceland and strontium isotope geochemistry, are consistent with the direction of flow predicted by the model.  相似文献