Design and evaluation of a geovisual analytics system for uncovering patterns in spatio-temporal event data     

Anthony C. Robinson  Donna J. Peuquet  Scott Pezanowski  Franklin A. Hardisty  Brian Swedberg 《制图学和地理信息科学》2013,40(3):216-228

ABSTRACT

It remains difficult to develop a clear understanding of geo-located events and their relationships to one another, particularly when it comes to identifying patterns of events in less-structured textual sources, such as news feeds and social media streams. Here we present a geovisualization tool that can leverage computational methods, such as T-pattern analysis, for extracting patterns of interest from event data streams. Our system, STempo, includes coordinated-view geovisualization components designed to support visual exploration and analysis of event data, and patterns extracted from those data, in terms of time, geography, and content. Through a user evaluation, we explore the usability and utility of STempo for understanding patterns of recent political, social, economic, and military events in Syria.  相似文献   

Investigating snowpack across scale in the northern Great Lakes–St. Lawrence forest region of Central Ontario,Canada     

Andy D. Beaton  Robert A. Metcalfe  James M. Buttle  Steven E. Franklin 《水文研究》2019,33(26):3310-3329

This study investigates scaling issues by evaluating snow processes and quantifying bias in snowpack properties across scale in a northern Great Lakes–St. Lawrence forest. Snow depth and density were measured along transects stratified by land cover over the 2015/2016 and 2016/2017 winters. Daily snow depth was measured using a time‐lapse (TL) camera at each transect. Semivariogram analysis of the transect data was conducted, and no autocorrelation was found, indicating little spatial structure along the transects. Pairwise differences in snow depth and snow water equivalent (SWE) between land covers were calculated and compared across scales. Differences in snowpack between forested sites at the TL points corresponded to differences in canopy cover, but this relationship was not evident at the transect scale, indicating a difference in observed process across scale. TL and transect estimates had substantial bias, but consistency in error was observed, which indicates that scaling coefficients may be derived to improve point scale estimates. TL and transect measurements were upscaled to estimate grid scale means. Upscaled estimates were compared and found to be consistent, indicating that appropriately stratified point scale measurements can be used to approximate a grid scale mean when transect data are not available. These findings are important in remote regions such as the study area, where frequent transect data may be difficult to obtain. TL, transect, and upscaled means were compared with modelled depth and SWE. Model comparisons with TL and transect data indicated that bias was dependent on land cover, measurement scale, and seasonality. Modelled means compared well with upscaled estimates, but model SWE was underestimated during spring melt. These findings highlight the importance of understanding the spatial representativeness of in situ measurements and the processes those measurements represent when validating gridded snow products or assimilating data into models.  相似文献   

For Whom Do We Write? Suggestions for Getting Read in the 21st Century     

Randall J. Hunt  Franklin W. Schwartz 《Ground water》2014,52(2):163-164

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Rietveld analysis of X‐ray powder diffraction patterns as a potential tool for the identification of impact‐deformed carbonate rocks     

Sarah A. Huson  Franklin F. Foit  A. John Watkinson  Michael C. Pope 《Meteoritics & planetary science》2009,44(11):1695-1706

Abstract— Previous X‐ray powder diffraction (XRD) studies revealed that shock deformed carbonates and quartz have broader XRD patterns than those of unshocked samples. Entire XRD patterns, single peak profiles and Rietveld refined parameters of carbonate samples from the Sierra Madera impact crater, west Texas, unshocked equivalent samples from 95 miles north of the crater and the Mission Canyon Formation of southwest Montana and western Wyoming were used to evaluate the use of X‐ray powder diffraction as a potential tool for distinguishing impact deformed rocks from unshocked and tectonically deformed rocks. At Sierra Madera dolostone and limestone samples were collected from the crater rim (lower shock intensity) and the central uplift (higher shock intensity). Unshocked equivalent dolostone samples were collected from well cores drilled outside of the impact crater. Carbonate rocks of the Mission Canyon Formation were sampled along a transect across the tectonic front of the Sevier and Laramide orogenic belts. Whereas calcite subjected to significant shock intensities at the Sierra Madera impact crater can be differentiated from tectonically deformed calcite from the Mission Canyon Formation using Rietveld refined peak profiles, weakly shocked calcite from the crater rim appears to be indistinguishable from the tectonically deformed calcite. In contrast, Rietveld analysis readily distinguishes shocked Sierra Madera dolomite from unshocked equivalent dolostone samples from outside the crater and tectonically deformed Mission Canyon Formation dolomite.  相似文献   

Hydrogen-isotopic variability in lipids from Santa Barbara Basin sediments     

Chao Li  Alex L. Sessions  Franklin S. Kinnaman 《Geochimica et cosmochimica acta》2009,73(16):4803-326

We conducted an extensive survey of hydrogen-isotopic compositions (D/H ratios) of diverse sedimentary lipids from the Santa Barbara Basin (SBB), offshore southern California. The main goal of this survey was to assess the diversity of D/H ratios in lipids from marine sediments, in order to provide a more detailed understanding of relevant biological and geochemical factors impacting lipid isotopic variability. A total of 1182 individual δD values are reported from two stations in SBB, one located in the suboxic basin depocenter and the other on the fully oxic flank of the basin. Sediments collected from the basin depocenter span a depth of ∼2.5 m and reach the methanogenic zone. Lipids that were analyzed include n-alkanes, n-alkanols and alkenols, short- and long-chain fatty acids, linear isoprenoids, steroids, and hopanoids, and exhibit several systematic patterns. First, there are no significant differences in δD values between the two sampling locations, nor with increasing depth for most lipids, indicating that degradation does not influence sedimentary lipid δD values. Second, relatively large differences in δD values among differing molecular structures are observed in all samples. n-Alkyl lipids of probable marine origin have typical δD values between −150 and −200‰, those from terrestrial leaf waxes and aquatic plants range from −80 to −170‰, while petroleum n-alkanes are typically −90 to −150‰. Third, lipids inferred to derive from bacteria (branched fatty acids and hopanols) living at the sediment surface or in the water column tend to be D-enriched relative to similar algal products by 30‰ or more. At the same time, several other lipids have δD values that decrease strongly with depth, presumably as a result of in situ production by anaerobic bacteria. This dichotomy in isotopic compositions of bacterial lipids is inconsistent with a nearly constant D/H fractionation during lipid biosynthesis, and likely reflects significant variations associated with metabolism.  相似文献   

Geometry and architecture of faults in a syn-rift normal fault array: The Nukhul half-graben, Suez rift, Egypt     

Paul Wilson  Rob L. Gawthorpe  David Hodgetts  Franklin Rarity  Ian R. Sharp 《Journal of Structural Geology》2009,31(8):759-775

The geometry and architecture of a well exposed syn-rift normal fault array in the Suez rift is examined. At pre-rift level, the Nukhul fault consists of a single zone of intense deformation up to 10 m wide, with a significant monocline in the hanging wall and much more limited folding in the footwall. At syn-rift level, the fault zone is characterised by a single discrete fault zone less than 2 m wide, with damage zone faults up to approximately 200 m into the hanging wall, and with no significant monocline developed. The evolution of the fault from a buried structure with associated fault-propagation folding, to a surface-breaking structure with associated surface faulting, has led to enhanced bedding-parallel slip at lower levels that is absent at higher levels. Strain is enhanced at breached relay ramps and bends inherited from pre-existing structures that were reactivated during rifting. Damage zone faults observed within the pre-rift show ramp-flat geometries associated with contrast in competency of the layers cut and commonly contain zones of scaly shale or clay smear. Damage zone faults within the syn-rift are commonly very straight, and may be discrete fault planes with no visible fault rock at the scale of observation, or contain relatively thin and simple zones of scaly shale or gouge. The geometric and architectural evolution of the fault array is interpreted to be the result of (i) the evolution from distributed trishear deformation during upward propagation of buried fault tips to surface faulting after faults breach the surface; (ii) differences in deformation response between lithified pre-rift units that display high competence contrasts during deformation, and unlithified syn-rift units that display low competence contrasts during deformation, and; (iii) the history of segmentation, growth and linkage of the faults that make up the fault array. This has important implications for fluid flow in fault zones.  相似文献   

Local- and watershed-scale controls on the spatial variability of natural levee deposits in a large fine-grained floodplain: Lower Pánuco Basin, Mexico     

Paul F. Hudson  Franklin T. Heitmuller 《Geomorphology》2003,56(3-4):255

This study examines spatial variations in natural levee deposits within the lower reaches of a large coastal plain drainage system. The Pánuco basin (98,227 km²) drains east-central Mexico, and is an excellent setting to examine the influence of watershed and local controls on the morphology and sedimentology of natural levees. Although many fluvial systems in the U.S. Gulf Coastal Plain have been investigated, the rivers in the Mexican Gulf Coastal Plain have received comparatively little attention. Lateral and downstream characteristics of natural levee morphology and sediment texture are considered within the context of meandering river floodplain deposits. Data sources include total-stations surveying, sediment samples of surficial levee deposits, topographic maps (1:50,000), and aerial photographs (1:40,000). The slope of natural levees average 0.0049 m/m, whereas the texture (D₈₄) of levee deposits averages 0.12 mm. Natural levee characteristics vary due to local- and watershed-scale controls. The lateral reduction in levee height displays a curvilinear pattern that coincides with an abrupt change in sediment texture. The downstream pattern of natural levee texture exhibits the influence of local-scale perturbations superimposed upon a larger watershed-scale trend. Disruption to the fining trend, either by tributary inputs of sediment or reworking of Tertiary valley deposits, is retained for a limited distance. The influence of the channel planform geometry on levee morphology is examined by consideration of the radius of curvature (R_c) of meander bends, and is inversely related to natural levee width. This suggests that the planform geometry of river channels exerts a control on the dispersal of flood sediments, and is responsible for considerable local variability in the floodplain topography. The average width of natural levees increases with drainage area, from an average of 747 m in the Moctezuma to an average of 894 m in the Pánuco. However, in the lower reaches of the Pánuco valley the width of natural levees rapidly decreases, which is associated with fining of the suspended sediment load. Thus, the reduction in natural levee width signifies an abrupt change in the directionality of cause–effect relationships at the watershed-scale. Findings from this study elucidate linkages between meandering river channels and floodplains for a large lowland alluvial valley.  相似文献   

Developments in triaxial testing technique     

Franklin  John A.  Hoeck  Evert 《Rock Mechanics and Rock Engineering》1970,2(4):223-228

Summary A simple triaxial cell is described together with details of the technique employed for triaxial testing. Triaxial strength results for 254 specimens of eight rock types are tabulated.

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Zusammenfassung Ein einfaches Triaxial-Prüfgerät wird, zusammen mit Einzelheiten des experimentellen Verfahrens, beschrieben. Ergebnisse dreiachsiger Festigkeitsprüfung sind für 254 Proben aus acht verschiedenen Gesteinsarten in Tabellen wiedergegeben.

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Résumé Un appareil triaxial simple est décrit avec des détails sur la technique expérimentale. Des résultats de résistance triaxiale pour 254 échantillons pris parmi huit types de roche sont donnés.

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With 2 Figures  相似文献   

Longitudinal characterization of a tidal marsh creek separating two hydrographically distinct estuaries     

Franklin B. Schwing  Björn Kjerfve 《Estuaries and Coasts》1980,3(4):236-241

Jones Creek, South Carolina, connects two hydrographically distinct estuarine systems: North Inlet and Winyah Bay. One hundred fifty-two sets of hydrographic measurements from February 1978 indicate the existence of a Jones Creek nodal point, an effective barrier limiting flow exchange between the end regions of the creek. Morphologic and vegetation observations and water quality ratings suggest that this nodal point is a permanent feature of Jones Creek and may be present in other similar systems.  相似文献   

The stability of transition metal dolomites in carbonate systems: a discussion     

Philip E. Rosenberg  Franklin F. Foit 《Geochimica et cosmochimica acta》1979,43(7):951-955

The instability of transition metal dolomites [CaR²⁺(CO₃)₂ where R²⁺ is Fe, Co, Ni, Cu, or Zn] and the limited substitution of transition metal cations for Mg in the dolomite structure can be accounted for by the effect of octahedral distortion. For example, trigonal elongation of the Fe octahedron, due to the Jahn-Teller effect, observed in siderite and ankerite, results in elongation of the Ca octahedron which is sensitive to distortion because the radius of Ca²⁺ is close to the upper limit for octahedral coordination. Co, Ni, Cu, Zn octahedra are also thought to be deformed, relative to Mg octahedra, in carbonates.The free energy of formation (ΔG^o_f) of R²⁺CO₃ becomes more positive with increasing octahedral distortion. Estimated ΔG^o_f(dolomite) as well as stabilities and solubility limits of R²⁺ in natural and synthetic dolomites suggest a series in order of decreasing stability: Mg >Mn >Zn >Fe >Co >Ni >Cu.ΔG^o_f(est.) for the terminal Fe-dolomite solid solution [72 mol% CaFe(CO₃)₂] in the system CaCO₃-MgCO₃-FeCO₃ may represent an empirical threshold value for dolomite stability which lies between ΔG^o_f for Mn- and Zn-dolomites. While Zn-dolomite is probably not a stable phase, very extensive solid solution toward CaZn(CO₃)₂ is to be expected in the system CaCO₃-MgCO₃-ZnCO₃. The tendency for transition metal dolomites to contain excess CaCO₃ can also be accounted for in terms of octahedral distortion and AG^o_f.  相似文献