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排序方式: 共有143条查询结果,搜索用时 347 毫秒
81.
82.
T. N. Krishnamurti Mukul Tewari Ed Bensman Wei Han Zhan Zhang William K. M. Lau 《大气科学进展》1999,16(2):159-182
1.IntroductionThispaperexploresanensembleforecaststrategyforthelarge--scaletropicalpredictionproblem.Thisisgeneralizedfromarecentstudyontheuseofempiricalorthogonalfunction(EOF)--basedperturbationsforhurricanetrackensembleforecasts,(ZhangandKrishnamur... 相似文献
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Hannah H. Kaplan Victoria E. Hamilton Ellen S. Howell F. Scott Anderson M. Antonella Barrucci John Brucato Thomas H. Burbine Beth E. Clark Ed A. Cloutis Harold C. Connolly Elisabetta Dotto Joshua P. Emery Sonia Fornasier Cateline Lantz Lucy F. Lim Frederic Merlin Alice Praet Dennis C. Reuter Scott A. Sandford Amy A. Simon Driss Takir Dante S. Lauretta 《Meteoritics & planetary science》2020,55(4):744-765
The primary objective of the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS‐REx) mission is to return to Earth a pristine sample of carbonaceous material from the primitive asteroid (101955) Bennu. To support compositional mapping of Bennu as part of sample site selection and characterization, we tested 95 spectral indices on visible to near infrared laboratory reflectance data from minerals and carbonaceous meteorites. Our aim was to determine which indices reliably identify spectral features of interest. Most spectral indices had high positive detection rates when applied to spectra of pure, single‐component materials. The meteorite spectra have fewer and weaker absorption features and, as a result, fewer detections with the spectral indices. Indices targeting absorptions at 0.7 and 2.7–3 μm, which are attributable to hydrated minerals, were most successful for the meteorites. Based on these results, we identified a set of 17 indices that are most likely to be useful at Bennu. These indices detect olivines, pyroxenes, carbonates, water/OH‐bearing minerals, serpentines, ferric minerals, and organics. Particle size and albedo are known to affect band depth but had a negligible impact on interpretive success with spectral indices. Preliminary analysis of the disk‐integrated Bennu spectrum with these indices is consistent with expectations given the observed absorption near 3 μm. Our study prioritizes spectral indices to be used for OSIRIS‐REx spectral analysis and mapping and informs the reliability of all index‐derived data products, including a science value map for sample site selection. 相似文献
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Residual displacement, as a significant measure of structural inelasticity, is effectively used in post-earthquake seismic assessment of structures. This demand can be considered for seismic evaluation of structures under multiple earthquakes. This study introduces a simple and novel index to predict the residual displacement of mainshock-damaged structures against subsequent aftershock. The proposed index is defined as a ratio between residual displacement of damaged structures against aftershock and peak inelastic displacement of intact structures under mainshock. In this study, constantstrength spectra based on the index are developed considering the effects of important structural characteristics and also significant seismic parameters. Moreover, analytical equations are presented to predict the proposed index for bi-linear single-degree-of-freedom(SDOF) systems considering both the effects of positive and negative polarities of aftershock. Furthermore, an equation is suggested to estimate the peak inelastic displacement of intact systems under mainshock, which is required to compute the index. 相似文献
85.
David Walsh Peter Turner Elliot Grunewald Hong Zhang James J. Butler Jr. Ed Reboulet Steve Knobbe Tom Christy John W. Lane Jr. Carole D. Johnson Tim Munday Andrew Fitzpatrick 《Ground water》2013,51(6):914-926
A small‐diameter nuclear magnetic resonance (NMR) logging tool has been developed and field tested at various sites in the United States and Australia. A novel design approach has produced relatively inexpensive, small‐diameter probes that can be run in open or PVC‐cased boreholes as small as 2 inches in diameter. The complete system, including surface electronics and various downhole probes, has been successfully tested in small‐diameter monitoring wells in a range of hydrogeological settings. A variant of the probe that can be deployed by a direct‐push machine has also been developed and tested in the field. The new NMR logging tool provides reliable, direct, and high‐resolution information that is of importance for groundwater studies. Specifically, the technology provides direct measurement of total water content (total porosity in the saturated zone or moisture content in the unsaturated zone), and estimates of relative pore‐size distribution (bound vs. mobile water content) and hydraulic conductivity. The NMR measurements show good agreement with ancillary data from lithologic logs, geophysical logs, and hydrogeologic measurements, and provide valuable information for groundwater investigations. 相似文献
86.
A simplified empirical equation is developed for widespread prediction of dynamic catchment response time. This model allows for time-to-peak prediction to evolve from static, lumped models, thereby providing a single value for any storm within a given catchment, using a single set of input parameters, that can be applied to a dynamic model, thus accounting for the variability between storm sizes and catchment moisture conditions. These dynamic prediction methods are translated to North America for the first time. This allows the concepts and prediction methods for catchment response time prediction previously established for the United Kingdom (UK), to be translated to a simple empirical equation for use in North America, through the use of selected study areas in Canada and the United States. This reconfigured model is statistically successful in both the UK and North America and allows for a straightforward implementation of dynamic time-to-peak prediction. Further, the reconfigured model introduces the use of a runoff coefficient (Rc) to encompass historical catchment wetness, increasing the ease of incorporating antecedent moisture condition into predictions. 相似文献
87.
The 2dF Galaxy Redshift Survey: correlation functions, peculiar velocities and the matter density of the Universe 总被引:1,自引:0,他引:1
Ed Hawkins Steve Maddox Shaun Cole Ofer Lahav Darren S. Madgwick Peder Norberg John A. Peacock Ivan K. Baldry Carlton M. Baugh Joss Bland-Hawthorn Terry Bridges Russell Cannon Matthew Colless Chris Collins Warrick Couch Gavin Dalton Roberto De Propris Simon P. Driver George Efstathiou Richard S. Ellis Carlos S. Frenk Karl Glazebrook Carole Jackson Bryn Jones Ian Lewis Stuart Lumsden Will Percival Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2003,346(1):78-96
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Sand beach ridges record 6000 year history of extreme tropical cyclone activity in northeastern Australia 总被引:1,自引:0,他引:1
Jonathan Nott Scott Smithers Kevin Walsh Ed Rhodes 《Quaternary Science Reviews》2009,28(15-16):1511-1520
Sand beach ridges are considered to be derived either from aeolian processes and/or waves but their deposition by individual or multiple storms has not been investigated in any detail. We use numerical meteorological and oceanographic models to determine the origin of a sequence of 29 shore parallel sand beach ridges in northeastern Australia. The results suggest that the ridges were constructed by waves and that the final form or height of the ridges is a function of high-energy tropical cyclone generated waves plus storm tides. Hence these landforms archive a nearly 6000 year long history of intense tropical cyclones. The record implies that these extreme tempests occur considerably more frequently than that suggested by the short historical record for this region. The genesis of this sand beach ridge plain has implications for the interpretation of similar sequences elsewhere along the northeast coast of Australia and in comparable environments globally. If other similar sand beach ridge plains have also been deposited by like processes it stands to reason that these long-term records of high intensity tropical cyclones can be used to ascertain a regional scale risk assessment from this hazard. 相似文献