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991.
Ran Tao Daniel Strandow Michael Findley Jean‐Claude Thill James Walsh 《Transactions in GIS》2016,20(3):413-425
Territorial control is central to the understanding of violent armed conflicts, yet reliable and valid measures of this concept do not exist. We argue that geospatial analysis provides an important perspective to measure the concept. In particular, measuring territorial control can be seen as an application of calculating service areas around points of control. The modeling challenge is acute for areas with limited road infrastructure, where no complete network is available to perform the analysis, and movements largely occur off road. We present a new geospatial approach that applies network analysis on a hybrid transportation network with both actual road data and hexagon‐fishnet‐based artificial road data representing on‐road and off‐road movements, respectively. Movement speed or restriction can be readily adjusted using various input data. Simulating off‐road movement with hexagon‐fishnet‐based artificial road data has a number of advantages including scalability to small or large study areas and flexibility to allow all‐directional travel. We apply this method to measuring territorial control of armed groups in Sub‐Saharan Africa where inferior transport infrastructure is the norm. Based on the Uppsala Conflict Data Program's (UCDP) Georeferenced Event Data (GED) as well as spatial data on terrain, population locations, and limited transportation networks, we enhance the delineation of the specific areas directly controlled by each warring party during civil wars within a given travel time. 相似文献
992.
Josi R. Taylor Andrew P. DeVogelaere Erica J. Burton Oren Frey Lonny Lundsten Linda A. Kuhnz P.J. Whaling Christopher Lovera Kurt R. Buck James P. Barry 《Marine pollution bulletin》2014
Carrying assorted cargo and covered with paints of varying toxicity, lost intermodal containers may take centuries to degrade on the deep seafloor. In June 2004, scientists from Monterey Bay Aquarium Research Institute (MBARI) discovered a recently lost container during a Remotely Operated Vehicle (ROV) dive on a sediment-covered seabed at 1281 m depth in Monterey Bay National Marine Sanctuary (MBNMS). The site was revisited by ROV in March 2011. Analyses of sediment samples and high-definition video indicate that faunal assemblages on the container’s exterior and the seabed within 10 m of the container differed significantly from those up to 500 m. The container surface provides hard substratum for colonization by taxa typically found in rocky habitats. However, some key taxa that dominate rocky areas were absent or rare on the container, perhaps related to its potential toxicity or limited time for colonization and growth. Ecological effects appear to be restricted to the container surface and the benthos within ∼10 m. 相似文献
993.
Social scientists and science communicators are concerned about the apparent discrepancy between the scientific consensus on climate change (Anderegg et al. Proc Natl Acad Sci 107:12107–12109, 2010; Doran and Zimmerman EOS Trans Am Geophys Union 90:22–3, 2009) and the general public’s views (Knight Environ Sociol 2:101–113, 2016; Lee et al. Nat Clim Chang 5:1014–1020, 2015). It is reasoned that increased public awareness and perceived threat of climate change may pressure governments to enact policy to counteract climate change (e.g. setting stringent carbon emissions targets). Despite a logical link between public awareness and government-set emissions targets, this relationship remains untested. We examined the relationship between public awareness about and perceived threat of climate change and governmental emissions targets across 71 countries and 1 region. We found a positive association between the proportions of a country’s population that are aware of climate change and the unconditional emissions reduction targets set by that country in the Paris Agreement (Rogelj et al. Nature 534:631–639, 2016). However, the proportion of people in a country who perceive climate change as a personal threat was not associated with higher emissions reduction targets. Our results suggest that public awareness may be an important part of garnering the public support required for policies designed to mitigate climate change to succeed. 相似文献
994.
David Nettle Galen P. Halverson Grant M. Cox Alan S. Collins Mark Schmitz James Gehling Peter R. Johnson Khalid Kadi 《地学学报》2014,26(2):120-129
The Ediacaran Jibalah Group comprises volcano‐sedimentary successions that filled small fault‐bound basins along the NW–SE‐trending Najd fault system in the eastern Arabian‐Nubian Shield. Like several other Jibalah basins, the Antaq basin contains exquisitely preserved sedimentary structures and felsic tuffs, and hence is an excellent candidate for calibrating late Ediacaran Earth history. Shallow‐marine strata from the upper Jibalah Group (Muraykhah Formation) contain a diversity of load structures and intimately related textured organic (microbial) surfaces, along with a fragment of a structure closely resembling an Ediacaran frond fossil and a possible specimen of Aspidella. Interspersed carbonate beds through the Muraykhah Formation record a positive δ13C shift from ?6 to 0‰. U‐Pb zircon geochronology indicates a maximum depositional age of ~570 Ma for the upper Jibalah Group, consistent with previous age estimates. Although this age overlaps with that of the upper Huqf Supergroup in nearby Oman, these sequences were deposited in contrasting tectonic settings on opposite sides of the final suture of the East African Orogen. 相似文献
995.
Trends in phosphatase activity along a successional gradient of tidal freshwater marshes on the Cooper River South Carolina 总被引:1,自引:0,他引:1
Phosphatase activity was measured in sediments from tidal freshwater habitats adjacent to the Cooper River in South Carolina
representing different stages of ecological succession. It was found that sediment (0–5 cm) acid phosphatase activity, alkaline
phosphatase activity and phosphodiesterase activity increased with increasing successional stage and phytomass. Acid phosphatase
activity in creased from 7.5±1.2 (±1 SD) in subtidal sediment from a shallow open water habitat without vegetation to 61.2±4.9
μmol g−1 hr−1 (μmol of p-nitrophenol released per gram of dry sediment per hour) in intertidal sediments colonized by emergent macrophytes,
while alkaline phosphatase activity increased from 2.1±0.1 to 19.01±1.5 μmol g−1 hr−1. Phosphodiesterase activity increased from 1.8±0.1 to 20.2±2.0 μmol g−1 hr−1 along the same gradient. Acid phosphatase activity was highly correlated (R2=0.92, P<0.001) with the organic matter content of the sediment. A study of phosphatase kinetics showed that Vmax of all phosphatases also increased along the successional gradient. Trends in phosphatase activity and Vmax correlated positively with plant biomass and negatively with concentrations of soluble reactive phosphorus in porewater,
sediment extractable phosphorus, and total phosphourus. The porewater N∶P atom ratio decreased along the succession gradient
from 25.3 in an early stage, open water community to 13.0 in a community dominated by emergent vegetation. The data also show
that the distribution of the forms of phosphorus changed with successional stage. The change in distribution and the increased
biological demand for phosphorus that paralleled succession were mediated by the activity of phosphatase enzymes. 相似文献
996.
Accurate real‐time hybrid earthquake simulations on large‐scale MDOF steel structure with nonlinear viscous dampers 下载免费PDF全文
This paper presents real‐time hybrid earthquake simulation (RTHS) on a large‐scale steel structure with nonlinear viscous dampers. The test structure includes a three‐story, single‐bay moment‐resisting frame (MRF), a three‐story, single‐bay frame with a nonlinear viscous damper and associated bracing in each story (called damped braced frame (DBF)), and gravity load system with associated seismic mass and gravity loads. To achieve the accurate RTHS results presented in this paper, several factors were considered comprehensively: (1) different arrangements of substructures for the RTHS; (2) dynamic characteristics of the test setup; (3) accurate integration of the equations of motion; (4) continuous movement of the servo‐controlled hydraulic actuators; (5) appropriate feedback signals to control the RTHS; and (6) adaptive compensation for potential control errors. Unlike most previous RTHS studies, where the actuator stroke was used as the feedback to control the RTHS, the present study uses the measured displacements of the experimental substructure as the feedback for the RTHS, to enable accurate displacements to be imposed on the experimental substructure. This improvement in approach was needed because of compliance and other dynamic characteristics of the test setup, which will be present in most large‐scale RTHS. RTHS with ground motions at the design basis earthquake and maximum considered earthquake levels were successfully performed, resulting in significant nonlinear response of the test structure, which makes accurate RTHS more challenging. Two phases of RTHS were conducted: in the first phase, the DBF is the experimental substructure, and in the second phase, the DBF together with the MRF is the experimental substructure. The results from the two phases of RTHS are presented and compared with numerical simulation results. An evaluation of the results shows that the RTHS approach used in this study provides a realistic and accurate simulation of the seismic response of a large‐scale structure with rate‐dependent energy dissipating devices. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
997.
998.
Abstract The Late Oligocene-Early Miocene Nabae Sub-belt of the Shimanto Accretionary Prism was created coevally (ca 25-15 Ma) with the opening of the Shikoku back-arc basin, located to the south of the southwest Japan convergent margin. The detailed geology of the sub-belt has been controversial and the interaction of the Shimanto accretionary prism and the opening of the Shikoku Basin has been ambiguous. New structural analysis of the sub-belt has led to a new perception of its structural framework and has significant bearing on the interpretation of the Neogene tectonics of southwest Japan. The sub-belt is divided into three units: the Nabae Complex; the Shijujiyama Formation; and the Maruyama Intrusive Suite. The Nabae Complex comprises coherent units and mélange, all of which show polyphase deformation. The first phase of deformation appears to have involved landward vergent thrusting of coherent units over the mélange terrane. The second phase of deformation involved continued landward vergent shortening. The Shijujiyama Formation, composed mainly of mafic volcanics and massive sandstone, is interpreted as a slope basin deposited upon the Nabae Complex during the second phase of deformation. The youngest deformational pulse involved regional flexing and accompanying pervasive faulting. During this event, mafic rocks of the Maruyama Intrusive Suite intruded the sub-belt. Fossil evidence in the Nabae Complex and radiometric dates on the intrusive rocks indicate that this tectonic scheme was imprinted upon the sub-belt between ~23 and ~14 Ma. The timing of accretion and deformation of the sub-belt coincides with the opening of the Shikoku Basin; hence, subduction and spreading operated simultaneously. Accretion of the Nabae Sub-belt was anomalous, involving landward vergent thrusting, magmatism in newly accreted strata and regional flexing. It is proposed that this complex and anomalous structural history is largely related to the subduction of the active Shikoku Basin spreading ridge and associated seamounts. 相似文献
999.
An accurate prediction of the thermal conductivity of reservoir rocks in the subsurface is extremely important for a quantitative analysis of basin thermal history and hydrocarbon maturation. A model for calculating the thermal conductivity of reservoir rocks as a function of mineral composition, porosity, fluid type, and temperature has been developed based on fabric theory and experimental data. The study indicates that thermal conductivities of reservoir rocks are dependent on the volume fraction of components (minerals, porosity, and fluids), the temperature, and the fraction of series elements (FSE) which represents the way that the mineral components aggregate. The sensitivity test of the fabric model shows that quartz is the most sensitive mineral for the thermal conductivity of clastic rocks. The study results indicate that the FSE value is very critical. Different lithologies have different optimum FSE values because of different textures and sedimentary structures. The optimum FSE values are defined as those which result in the least error in the model computation of the thermal conductivity of the rocks. These values are 0.444 for water-saturated clay rocks, 0.498 for water-saturated sandstones, and 0.337 for water-saturated carbonates. Compared with the geometric mean model, the fabric model yields better results for the thermal conductivity, largely because the model parameters can be adjusted to satisfy different lithologies and to minimize the mean errors. The fabric model provides a good approach for estimating paleothermal conductivity in complex rock systems based on the mineral composition and pore fluid saturation of the rocks. 相似文献
1000.