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Penelope J. Wozniakiewicz Anton T. Kearsley Mark J. Burchell Mark C. Price Hope A. Ishii Michael J. Cole 《Meteoritics & planetary science》2018,53(5):1066-1080
Over the last decade, silica aerogel tracks and aluminum foil craters on the Stardust collector have been studied extensively to determine the nature of captured cometary dust grains. Analysis of particles captured in aerogel has been developed to a fine art, aided by sophisticated preparation techniques, and yielding revolutionary knowledge of comet dust mineralogy. The Stardust foil craters can be interpreted in terms of impacting particle size and structure, but almost all studies of composition for their contents have relied on in situ analysis techniques or relatively destructive extraction of materials. This has limited their examination and interpretation. However, numerous experimental hypervelocity impact studies under Stardust-Wild 2 encounter conditions have shown that abundant dust components are preserved in foil craters of all sizes. Using some of these analogue materials, we have previously shown that modern, nondestructive scanning electron microscope imaging and X-ray microanalysis techniques can document distribution of dust remnants both quickly and thoroughly within foil craters prior to any preparation. Here we present findings from our efforts to quantify the amount of residue and demonstrate a simple method of crater shape modification which can bring material into positions where it is much more accessible for in situ analysis, or safe removal of small subsamples. We report that approximately 50% of silicate-dominated impactors were retained as impact crater residue; however, <3% of organic impactors remained in the craters after impact. 相似文献
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Alex Rattray Daniel Ierodiaconou Laurie Laurenson Shoaib Burq Marcus Reston 《Estuarine, Coastal and Shelf Science》2009
Information regarding the composition and extent of benthic habitats on the South East Australian continental shelf is limited. In this habitat mapping study, multibeam echosounder (MBES) data are integrated with precisely geo-referenced video ground-truth data to quantify benthic biotic communities at Cape Nelson, Victoria, Australia. Using an automated decision tree classification approach, 5 representative biotic groups defined from video analysis were related to hydro-acoustically derived variables in the Cape Nelson survey area. Using a combination of multibeam bathymetry, backscatter and derivative products produced highest overall accuracy (87%) and kappa statistic (0.83). This study demonstrates that decision tree classifiers are capable of integrating variable data types for mapping distributions of benthic biological assemblages, which are important in maintaining biodiversity and other system services in the marine environment. 相似文献
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Papadopoulou Penelope Iliopoulos George Tsoni Maria Koukouvelas Ioannis Groumpos Petros 《Mathematical Geosciences》2021,53(8):1841-1860
Mathematical Geosciences - This work aims to test and introduce a newly developed methodological approach for palaeoenvironmental reconstructions using advanced intelligent controls, namely fuzzy... 相似文献
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Abstract: This paper considers the political and normative dimensions of local government responses to homelessness in New Zealand. It outlines the context for local government action, the approaches adopted by three case study cities, and arguments for rejecting anti-homeless regulations in favour of supportive policies conducive to forging inclusive public space. It contributes to debates over homelessness policy by articulating an approach that integrates regulatory, funding and leadership roles. It argues that in addressing antisocial behaviour in public spaces, policy-makers must eschew approaches which effectively criminalize the sight, and status, of poverty. 相似文献
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The biodiversity record of graptolites from the Cheeseman's Creek Formation, considered herein as late Gisbornian (Caradoc) in age, has been substantially increased to fifteen taxa, including the new species Dicellograptus praemorrisi sp. nov. and Climacograptus vandenbergi sp. nov. Some of the records have global correlative significance enabling us to identify the wilsoni Biozone ( = calcaratus Biozone of eastern Australia). Several evolutionary lineages have been recognized:
- 1 Dicellograptus moffatensis (Carruthers, 1858) → D. praemorrisi sp. nov → D. morrisi Hopkinson, 1871
- 2 Glossograptus hincksi Hopkinson, 1872 → Glossograptus? sp.
- 3 Climacograptus bicornis (J. Hall, 1847) → C. vandenbergi sp. nov. → C. lanceolatus VandenBerg, 1990.