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Thi Hong Diep Dao Craig Ravesloot Lillie Greiman Tannis Hargrove 《Transactions in GIS》2019,23(3):515-537
The geographical explicit ecological momentary assessment (GEMA) data collection platform provides extremely rich geospatial datasets and is very promising to gain behavior insights linking mobility, activities, and health. However, the task of analyzing these large datasets effectively is not straightforward, because they often involve a large multivariable dimension and rich qualitative data formats. Responding to the call for innovative analytic approaches in GIScience, this article advocates the use of spatial association rule mining (SARM) to extract frequent associations among daily activities, daily mobility, and health, including both physical health (e.g. pain) and mental health (e.g. happiness). This inductive mining approach works robustly with large datasets and is suitable for both qualitative and quantitative studies. A novel visualization technique to analyze the mined rules is also developed and presented. 相似文献
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Kelsey D. Hargrove Michael S. Kelley Humberto Campins Javier Licandro Josh Emery 《Icarus》2012,221(1):453-455
We find a clear diversity in the 3 μm and 10 μm features of three Cybele asteroids: (107) Camilla, (121) Hermione, and (65) Cybele. (121) Hermione exhibits a “check-like” 3 μm feature, which may be attributed to OH-dominated minerals and (107) Camilla shows a rounded “bowl” like feature closer to that of (65) Cybele, which may be attributed to H2O-dominated minerals. The 10 μm features of these three asteroids are also different from each other. 相似文献
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Processes of magma/wet sediment interaction in a large-scale Jurassic andesitic peperite complex, northern Sierra Nevada, California 总被引:3,自引:0,他引:3
The Middle Jurassic Tuttle Lake Formation in the northern Sierra Nevada, California, comprises a thick volcaniclastic sequence
deposited in a submarine island-arc setting and penetrated by numerous related hypabyssal intrusions. A composite andesite-diorite
intrusive complex ≥4.5 km long and ≥1.5 km thick was emplaced while the host Tuttle Lake sediments were still wet and unconsolidated.
Large parts of the intrusive complex consist of peperite formed where andesitic magma intruded and intermixed with tuff, lapilli-tuff
and tuff-breccia. The southern half of the complex consists of augite-phyric andesite containing peperite in numerous small,
isolated pockets and in more extensive, laterally continuous zones. The peperites comprise three main types recognized previously
in other peperite studies. Fluidal peperite consists of small (≤30 cm), closely spaced, at least partly interconnected, globular to amoeboid andesite bodies enclosed
by tuff. This peperite type developed during intrusion of magma into fine-grained wet sediment along unstable interfaces,
and fluidization of the sediment facilitated development of complex intrusive geometries. Blocky peperite and mixed blocky and fluidal peperite formed where magma intruded coarser sediment and underwent variable degrees of brittle fragmentation by quenching and dynamic
stressing of rigid margins, possibly aided by small steam explosions. The northern half of the intrusive complex consists
predominantly of a different type of peperite, in which decimetre-scale plagioclase-phyric andesite clasts with ellipsoidal,
elongate, or angular, polyhedral shapes are closely packed to widely dispersed within disrupted host sediment. Textural features
suggest the andesite clasts were derived from conduits through which magma was flowing, and preserved remnants of the conduits
are represented by elongate, sinuous bodies up to 30 m or more in length. Disruption and dispersal of the andesite clasts
are inferred to have occurred at least partly by steam explosions that ripped apart a network of interconnected feeder conduits
penetrating the host sediments. Closely packed peperite is present adjacent to mappable intrusions of coherent andesite, and
along the margin of a large mass of coarse-grained diorite. These coherent intrusions are considered to be major feeders for
this part of the complex. Examples of magma/wet sediment interaction similar in scale to the extensive peperites described
here occur elsewhere in ancient island-arc strata in the northern Sierra Nevada. Based on these and other published examples,
large-scale peperites probably are more common than generally realized and are likely to be important in settings where thick
sediment sequences accumulate during active volcanism. Careful mapping in well-exposed terrains may be required to recognize
large-scale peperite complexes of this type.
Received: 8 June 1998 / Accepted: 4 December 1998 相似文献
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We investigate the morphological variation of classical meteor light curves, under the constant velocity assumption, for a
series of idealized atmospheric density profiles. We look specifically at the t
rise
/t
fall
ratio, which compares the rise time to maximum brightness against the time to fall from maximum brightness. We demonstrate
that for a classical meteoroid undergoing rapid ablation in an isothermal atmosphere that t
rise/t
fall > 1, indicating that all such light curves are late peaked. For a classical meteoroid ablating in a region over which the
density is constant, t
rise/t
fall≡ 0, and the light curve is necessarily downward concave in the height vs. intensity diagram. If ablation occurs over a region
in which the density increases linearly with decreasing height, then t
rise/t
fall=1/(√5 – 1) ≈ 0.81, indicative of an early peaked, near symmetric light curve. 相似文献
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Humberto Campins Michael S. Kelley Yanga Fernández Javier Licandro Kelsey Hargrove 《Earth, Moon, and Planets》2009,105(2-4):159-165
We present initial results from a study of a sample of low-perihelion near-Earth asteroids (NEAs) using the Infrared Spectrograph (IRS) on NASA’s Spitzer Space Telescope. The 7–14 μm thermal emission spectra have been fitted with models of the thermal continuum to derive the asteroid’s effective diameter, geometric albedo and beaming parameter η. In this work, we concentrate on the thermal behavior and we find a trend of increasing η (lower thermal fluxes and cooler color temperatures) with increasing solar phase angle. The slope of this trend is somewhat different from that reported for other NEAs (e.g., Delbó 2004); if confirmed, this result would indicate that the thermal behavior of low-perihelion asteroids is different from that of other members of the NEA population. In addition, deviations of the observed continuum from the thermal model, which can be diagnostic of composition, are apparent in a few of our targets. A complete characterization of these intrinsically faint objects will benefit from the large ground based facilities described elsewhere in these proceedings. 相似文献
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Changes in climate as projected by state-of-the-art climate models are likely to result in novel combinations of climate and topo-edaphic factors that will have substantial impacts on the distribution and persistence of natural vegetation and animal species. We have used multivariate techniques to quantify some of these changes; the method employed was the Multivariate Spatio-Temporal Clustering (MSTC) algorithm. We used the MSTC to quantitatively define ecoregions for the People’s Republic of China for historical and projected future climates. Using the Köppen–Trewartha classification system we were able to quantify some of the temperature and precipitation relationships of the ecoregions. We then tested the hypothesis that impacts to environments will be lower for ecoregions that retain their approximate geographic locations. Our results showed that climate in 2050, as projected from anthropogenic forcings using the Hadley Centre HadCM3 general circulation model, were sufficient to create novel environmental conditions even where ecoregions remained spatially stable; cluster number was found to be of paramount importance in detecting novelty. Continental-scale analyses are generally able to locate potentially static ecoregions but they may be insufficient to define the position of those reserves at a grid cell-by-grid cell basis. 相似文献
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