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排序方式: 共有667条查询结果,搜索用时 109 毫秒
661.
Shaun Cole Will J. Percival John A. Peacock Peder Norberg Carlton M. Baugh Carlos S. Frenk Ivan Baldry Joss Bland-Hawthorn Terry Bridges Russell Cannon Matthew Colless Chris Collins Warrick Couch Nicholas J. G. Cross Gavin Dalton Vincent R. Eke Roberto De Propris Simon P. Driver George Efstathiou Richard S. Ellis Karl Glazebrook Carole Jackson Adrian Jenkins Ofer Lahav Ian Lewis Stuart Lumsden Steve Maddox Darren Madgwick Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2005,362(2):505-534
662.
Massimiliano Galeazzi Meng Chiao Michael R. Collier Thomas Cravens Dimitra Koutroumpa Kip D. Kuntz Susan Lepri Dan McCammon Frederick S. Porter Krishna Prasai Ina Robertson Steve Snowden Youaraj Uprety 《Experimental Astronomy》2011,32(2):83-99
The Diffuse X-rays from the Local galaxy (DXL) mission is an approved sounding rocket project with a first launch scheduled around December 2012. Its goal is to identify and separate the X-ray emission generated by solar wind charge exchange from that of the local hot bubble to improve our understanding of both. With 1,000 cm2 proportional counters and grasp of about 10 cm2 sr both in the 1/4 and 3/4 keV bands, DXL will achieve in a 5-min flight what cannot be achieved by current and future X-ray satellites. 相似文献
663.
Hazard assessment model for debris flow prediction 总被引:4,自引:3,他引:1
Debris flow disasters have plagued Taiwan in recent decades, and caused casualties and destruction of property. Several methods,
including the numerical method, statistical method, and experimental method, have been adopted in recent years to predict
debris flow, and more recently, the neural network (NN) and the genetic algorithm (GA) methods have been introduced to simulate
the occurrence of debris flows. This study proposes using the GA to weigh seven important variables according to principles
similar to natural selection. The study then simultaneously inputs these variables into a NN model to predict debris flow
occurrences based on relevant factors. There were 154 potential cases of debris flow collected from eastern Taiwan and fed
into the model for testing. The average ratio of successful prediction reached 94.94%, which demonstrates that the proposed
model can provide stable and reliable results for predicting debris flow in hazard mitigation and guard systems. 相似文献
664.
John C. BRIDGES Mark J. BURCHELL Hitesh C. CHANGELA Nick J. FOSTER J. Alan CREIGHTON James D. CARPENTER Steve J. GURMAN Ian A. FRANCHI Henner BUSEMANN 《Meteoritics & planetary science》2010,45(1):55-72
Abstract– We have used synchrotron Fe‐XANES, XRS, microRaman, and SEM‐TEM analyses of Stardust track 41 slice and track 121 terminal area slices to identify Fe oxide (magnetite‐hematite and amorphous oxide), Fe‐Ti oxide, and V‐rich chromite (Fe‐Cr‐V‐Ti‐Mn oxide) grains ranging in size from 200 nm to ~10 μm. They co‐exist with relict FeNi metal. Both Fe‐XANES and microRaman analyses suggest that the FeNi metal and magnetite (Fe2O3FeO) also contain some hematite (Fe2O3). The FeNi has been partially oxidized (probably during capture), but on the basis of our experimental work with a light‐gas gun and microRaman analyses, we believe that some of the magnetite‐hematite mixtures may have originated on Wild 2. The terminal samples from track 121 also contain traces of sulfide and Mg‐rich silicate minerals. Our results show an unequilibrated mixture of reduced and oxidized Fe‐bearing minerals in the Wild 2 samples in an analogous way to mineral assemblages seen in carbonaceous chondrites and interplanetary dust particles. The samples contain some evidence for terrestrial contamination, for example, occasional Zn‐bearing grains and amorphous Fe oxide in track 121 for which evidence of a cometary origin is lacking. 相似文献
665.
Mort Webster Andrei P. Sokolov John M. Reilly Chris E. Forest Sergey Paltsev Adam Schlosser Chien Wang David Kicklighter Marcus Sarofim Jerry Melillo Ronald G. Prinn Henry D. Jacoby 《Climatic change》2012,112(3-4):569-583
Although policymaking in response to the climate change threat is essentially a challenge of risk management, most studies of the relation of emissions targets to desired climate outcomes are either deterministic or subject to a limited representation of the underlying uncertainties. Monte Carlo simulation, applied to the MIT Integrated Global System Model (an integrated economic and earth system model of intermediate complexity), is used to analyze the uncertain outcomes that flow from a set of century-scale emissions paths developed originally for a study by the U.S. Climate Change Science Program. The resulting uncertainty in temperature change and other impacts under these targets is used to illustrate three insights not obtainable from deterministic analyses: that the reduction of extreme temperature changes under emissions constraints is greater than the reduction in the median reduction; that the incremental gain from tighter constraints is not linear and depends on the target to be avoided; and that comparing median results across models can greatly understate the uncertainty in any single model. 相似文献
666.
667.
A series of molecular dynamics simulations have been performed on organic–water mixtures near mineral surfaces. These simulations show that, in contrast to apolar compounds, small polar organic compounds such as phenols can penetrate through thin water films to adsorb on these mineral surfaces. Furthermore, additional simulations involving demixing of an organic–water mixture near a surfactant-covered mineral surface demonstrate that even low concentrations of adsorbed polar compounds can induce major changes in mineral surface wettability, allowing sorption of apolar molecules. This strongly supports a two-stage adsorption mechanism for organic solutes, involving initial migration of small polar organic molecules to the mineral surface followed by water film displacement due to co-adsorption of the more apolar organic compounds, thus converting an initial water-wet mineral system to an organic-covered surface. This has profound implications for studies of petroleum reservoir diagenesis and wettability changes. 相似文献