Modelling the risk of deterioration at earthen heritage sites in drylands     

Jenny Richards  Jerome Mayaud  Hongtao Zhan  Fasi Wu  Richard Bailey  Heather Viles 《地球表面变化过程与地形》2020,45(11):2401-2416

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Confirmation of eclipses in KPD 0422+5421, a binary containing a white dwarf and a subdwarf B star     

Jerome A. Orosz †  Richard A. Wade 《Monthly notices of the Royal Astronomical Society》1999,310(3):773-783

We report additional photometric CCD observations of KPD 0422+5421, a binary with an orbital period of 2.16 h which contains a subdwarf B star (sdB) and a white dwarf. There are two main results of this work. First, the light curve of KPD 0422+5421 contains two distinct periodic signals, the 2.16-h ellipsoidal modulation discovered by Koen, Orosz & Wade and an additional modulation at 7.8 h. This 7.8-h modulation is clearly not sinusoidal: the rise time is about 0.25 in phase, whereas the decay time is 0.75 in phase. Its amplitude is roughly half of the amplitude of the ellipsoidal modulation. Secondly, after the 7.8-h modulation is removed, the light curve folded on the orbital period clearly shows the signature of the transit of the white dwarf across the face of the sdB star and the signature of the occultation of the white dwarf by the sdB star. We have used the Wilson–Devinney code to model the light curve to obtain the inclination, the mass ratio and the Ω potentials, and a Monte Carlo code to compute confidence limits on interesting system parameters. We find component masses of     and     ( M _total     , 68 per cent confidence limits). If we impose an additional constraint and require the computed mass and radius of the white dwarf to be consistent with a theoretical mass–radius relation, we find     and     (68 per cent confidence limits). In this case the total mass of the system is less than 1.4 M_⊙ at the 99.99 per cent confidence level. We briefly discuss possible interpretations of the 7.8-h modulation and the importance of KPD 0422+5421 as a member of a rare class of evolved binaries.  相似文献   

Design and Analysis for Modeling and Predicting Spatial Contamination     

Markus Abt  William J. Welch  Jerome Sacks 《Mathematical Geology》1999,31(1):1-22

Sampling and prediction strategies relevant at the planning stage of the cleanup of environmental hazards are discussed. Sampling designs and models are compared using an extensive set of data on dioxin contamination at Piazza Road, Missouri. To meet the assumptions of the statistical model, such data are often transformed by taking logarithms. Predicted values may be required on the untransformed scale, however, and several predictors are also compared. Fairly small designs turn out to be sufficient for model fitting and for predicting. For fitting, taking replicates ensures a positive measurement error variance and smooths the predictor. This is strongly advised for standard predictors. Alternatively, we propose a predictor linear in the untransformed data, with coefficients derived from a model fitted to the logarithms of the data. It performs well on the Piazza Road data, even with no replication.  相似文献   

The Monitor project: rotation periods of low-mass stars in M50     

Jonathan Irwin  Suzanne Aigrain  Jerome Bouvier  Leslie Hebb  Simon Hodgkin  Mike Irwin  Estelle Moraux 《Monthly notices of the Royal Astronomical Society》2009,392(4):1456-1466

We report on the results of a time-series photometric survey of M50 (NGC 2323), a  ∼130 Myr  open cluster, carried out using the Cerro Tololo Inter-American Observatory (CTIO) 4-m Blanco telescope and Mosaic-II detector as part of the Monitor project. Rotation periods were derived for 812 candidate cluster members over the mass range  0.2 ≲ M /M_⊙≲ 1.1  . The rotation period distributions show a clear mass-dependent morphology, statistically indistinguishable from those in NGC 2516 and M35 taken from the literature. Due to the availability of data from three observing runs separated by ∼10 and 1 month time-scales, we are able to demonstrate clear evidence for evolution of the photometric amplitudes, and hence spot patterns, over the 10 month gap. We are not able to constrain the time-scales for these effects in detail due to limitations imposed by the large gaps in our sampling, which also prevent the use of the phase information.  相似文献   

Intersecting dilated convex polyhedra method for modeling complex particles in discrete element method     

Ben Nye  Anton V. Kulchitsky  Jerome B. Johnson 《国际地质力学数值与分析法杂志》2014,38(9):978-990

This paper describes a new method for representing concave polyhedral particles in a discrete element method as unions of convex dilated polyhedra. This method offers an efficient way to simulate systems with a large number of (generally concave) polyhedral particles. The method also allows spheres, capsules, and dilated triangles to be combined with polyhedra using the same approach. The computational efficiency of the method is tested in two different simulation setups using different efficiency metrics for seven particle types: spheres, clusters of three spheres, clusters of four spheres, tetrahedra, cubes, unions of two octahedra (concave), and a model of a computer tomography scan of a lunar simulant GRC‐3 particle. It is shown that the computational efficiency of the simulations degrades much slower than the increase in complexity of the particles in the system. The efficiency of the method is based on the time coherence of the system, and an efficient and robust distance computation method between polyhedra as particles never intersect for dilated particles. © 2014 The Authors. International Journal for Numerical and Analytical Methods in Geomechanics published by John Wiley & Sons Ltd.  相似文献   

Combined element (H and C) stable isotope ratios of methane in carbonaceous chondrites     

Anna L. Butterworth  Olivier Aballain  Jerome Chappellaz  Mark A. Sephton † 《Monthly notices of the Royal Astronomical Society》2004,347(3):807-812

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The dynamical evolution of Taurus–Auriga-type aggregates     

Pavel Kroupa †  Jerome Bouvier 《Monthly notices of the Royal Astronomical Society》2003,346(2):343-353

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The First Quantitative Slip-Rate Estimated Along the Ashikule Fault at the Western Segment of the Altyn Tagh Fault System     

PAN Jiawei  LI Haibing  VAN DER WOERD Jerome  SUN Zhiming  SI Jialiang  PEI Junling  WU Fuyao  CHEVALIER Marie-Luce 《《地质学报》英文版》2015,89(6):2088-2089

<正>As one of the longest strike-slip fault in Asia,the Altyn Tagh Fault(ATF)defines the northern boundary of the Tibetan Plateau and plays a significant role inaccommodating the deformation resulting from the IndiaAsia convergence.Slip-rate and seismic behavior of the fault are critical to understand the present-day kinematics  相似文献   

The Vicência meteorite fall: A new unshocked (S1) weakly metamorphosed (3.2) LL chondrite          下载免费PDF全文

Klaus Keil  Maria E. Zucolotto  Alexander N. Krot  Patricia M. Doyle  Myriam Telus  Tatiana V. Krot  Richard C. Greenwood  Ian A. Franchi  John T. Wasson  Kees C. Welten  Marc W. Caffee  Derek W. G. Sears  My Riebe  Rainer Wieler  Edivaldo dos Santos  Rosa B. Scorzelli  Jerome Gattacceca  France Lagroix  Matthias Laubenstein  Julio C. Mendes  Philippe Schmitt‐Kopplin  Mourad Harir  Andre L. R. Moutinho 《Meteoritics & planetary science》2015,50(6):1089-1111

The Vicência meteorite, a stone of 1.547 kg, fell on September 21, 2013, at the village Borracha, near the city of Vicência, Pernambuco, Brazil. It was recovered immediately after the fall, and our consortium study showed it to be an unshocked (S1) LL3.2 ordinary chondrite. The LL group classification is based on the bulk density (3.13 g cm^?3); the chondrule mean apparent diameter (0.9 mm); the bulk oxygen isotopic composition (δ¹⁷O = 3.768 ± 0.042‰, δ¹⁸O = 5.359 ± 0.042‰, Δ¹⁷O = 0.981 ± 0.020‰); the content of metallic Fe,Ni (1.8 vol%); the Co content of kamacite (1.73 wt%); the bulk contents of the siderophile elements Ir and Co versus Au; and the ratios of metallic Fe⁰/total iron (0.105) versus total Fe/Mg (1.164), and of Ni/Mg (0.057) versus total Fe/Mg. The petrologic type 3.2 classification is indicated by the beautifully developed chondritic texture, the standard deviation (~0.09) versus mean Cr₂O₃ content (~0.14 wt%) of ferroan olivine, the TL sensitivity and the peak temperature and peak width at half maximum, the cathodoluminescence properties of chondrules, the content of trapped ¹³²Xe_tr (0.317 × 10^?8cm³STP g^?1), and the Raman spectra for organic material in the matrix. The cosmic ray exposure age is ~72 Ma, which is at the upper end of the age distribution of LL group chondrites. The meteorite is unusual in that it contains relatively large, up to nearly 100 μm in size, secondary fayalite grains, defined as olivine with Fa_>75, large enough to allow in situ measurement of oxygen and Mn‐Cr isotope systematics with SIMS. Its oxygen isotopes plot along a mass‐dependent fractionation line with a slope of ~0.5 and Δ¹⁷O of 4.0 ± 0.3‰, and are similar to those of secondary fayalite and magnetite in the unequilibrated chondrites EET 90161, MET 96503, and Ngawi. These data suggest that secondary fayalite in Vicência was in equilibrium with a fluid with a Δ¹⁷O of ~4‰, consistent with the composition of the fluid in equilibrium with secondary magnetite and fayalite in other unequilibrated ordinary chondrites. Secondary fayalite and the chondrule olivine phenocrysts in Vicência are not in isotopic equilibrium, consistent with low‐temperature formation of fayalite during aqueous alteration on the LL parent body. That alteration, as dated by the ⁵³Mn‐⁵³Cr chronology age of secondary fayalite, took place $4.0{}_{?1.1}^{+1.4}$ Ma after formation of CV CAIs when anchored to the quenched angrite D'Orbigny.  相似文献   

Lagrangian Stochastic Modelling of Dispersion in the Convective Boundary Layer with Skewed Turbulence Conditions and a Vertical Density Gradient: Formulation and Implementation in the FLEXPART Model     

Massimo Cassiani  Andreas Stohl  Jerome Brioude 《Boundary-Layer Meteorology》2015,154(3):367-390

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