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961.
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963.
Robert Balk 《International Journal of Earth Sciences》1953,41(1):90-103
English summary Near the eastern base of the Taconic Range, in extreme southwestern Vermont, a complex of chlorite slate is exposed in the position of the floor of a thrust along which a mass of dolomite-limestone has been pushed from the east against, and over, the slate. In addition to the common structure, exhibiting westward-overturned open folds, with slip cleavage dipping eastward, about parallel with the axial pianos, the slate displays a number of subsidiary shears or thrust zones having the same orientation as the principal thrust. In these zones, a strong lineation as well as axes of small folds plunge E—SE, parallel with the direction of propagation of the thrust blocks. The origin of the lineation and lamination is believed to be identical with that of corresponding structures in rolled steel and glass.However, the formation of folds with axes parallel to the direction of thrust requires an additional shear stress acting perpendicularly to the direction of thrusting. The inhomogeneous composition, strength, and mobility of the flooring rocks are pointed out, and it is suggested that unequal rates of yielding of local rock masses below the thrust block generated these supplementary stresses, producing slight movements of small masses sideways. That this is a reasonable explantation is shown by experiments on salt dome structure byEscher andKuenen, in which also axes of folds and lineation parallel with the direction of maximum forward propagation were produced. 相似文献
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Ohne Zusammenfassung 相似文献
967.
Zhenglong LI Jun LI Pei WANG Agnes LIM Jinlong LI Timothy J.SCHMIT Robert ATLAS Sid-Ahmed BOUKABARA Ross N.HOFFMAN 《大气科学进展》2018,35(10):1217-1230
Accurate atmospheric temperature and moisture information with high temporal/spatial resolutions are two of the key parameters needed in regional numerical weather prediction(NWP) models to reliably predict high-impact weather events such as local severe storms(LSSs). High spectral resolution or hyperspectral infrared(HIR) sounders from geostationary orbit(GEO) provide an unprecedented source of near time-continuous, three-dimensional information on the dynamic and thermodynamic atmospheric fields—an important benefit for nowcasting and NWP-based forecasting. In order to demonstrate the value of GEO HIR sounder radiances on LSS forecasts, a quick regional OSSE(Observing System Simulation Experiment)framework has been developed, including high-resolution nature run generation, synthetic observation simulation and validation, and impact study on LSS forecasts. Results show that, on top of the existing LEO(low earth orbit) sounders, a GEO HIR sounder may provide value-added impact [a reduction of 3.56% in normalized root-mean-square difference(RMSD)] on LSS forecasts due to large spatial coverage and high temporal resolution, even though the data are assimilated every 6 h with a thinning of 60 km. Additionally, more frequent assimilations and smaller thinning distances allow more observations to be assimilated, and may further increase the positive impact from a GEO HIR sounder. On the other hand, with denser and more frequent observations assimilated, it becomes more difficult to handle the spatial error correlation in observations and gravity waves due to the limitations of current assimilation and forecast systems(such as a static background error covariance). The peak reduction of 4.6% in normalized RMSD is found when observations are assimilated every 3 h with a thinning distance of 30 km. 相似文献
968.
Sami Eria Robert B. McMaster 《International journal of geographical information science》2017,31(5):884-906
Despite myriad studies having been carried out on the diffusion of geographical information systems (GIS) technology, only a limited number have been done within the context of developing countries. This paper addresses the research question, how did the diffusion of GIS technology occur in Uganda? Mixed methods were used for data collection, and analysis was performed using a theoretical framework called the diffusion of innovations (DOI). The results of the study showed that the adoption of GIS by institutions in Uganda occurred in a classic diffusion pattern consistent with diffusion theory. Adoption of GIS was promoted by its relative advantage over, and compatibility with, existing technologies. It was characterized by both heterophilous and homophilous communication channels, and influenced by change agents and champions. Its rate of adoption followed an S-shaped diffusion curve, and was hampered by bureaucracy, and patronage-based societal norms. This study makes a contribution to literature on GIS diffusion in developing countries. 相似文献
969.
Variations in the stone covers on desert surfaces have implications for the operation of hydrological processes. Some recent attention has been given to the difficulties of identifying and quantifying relevant characteristics of stone covers. Investigation of how such characteristics vary in relation to geological and topographical controls are limited. Results are presented of a field study of the characteristics of stone covers on four lithologies in the late Tertiary to Quaternary basalt plateau of northeast Jordan. Marked variations occur in clast dimensions and the characteristics of sorting between lithologies which are likely to affect hydrological response. A more subtle control, relating to slope conditions, is superimposed on the lithological differences. R- and Q-mode factor analysis identifies groupings within the data, which demonstrate the distinctiveness of different lithologies. Characteristics of the stone covers on sites affected by human occupation are markedly different from undisturbed sites on the same lithology. 相似文献
970.
Analysis of Difference Between Direct and Geodetic Mass Balance Measurements at South Cascade Glacier, Washington 总被引:2,自引:0,他引:2
Robert M. Krimmel 《Geografiska Annaler: Series A, Physical Geography》1999,81(4):653-658
Net mass balance has been measured since 1958 at South Cascade Glacier using the 'direct method,' e.g. area averages of snow gain and firn and ice loss at stakes. Analysis of cartographic vertical photography has allowed measurement of mass balance using the 'geodetic method' in 1970, 1975, 1977, 1979–80, and 1985–97. Water equivalent change as measured by these nearly independent methods should give similar results. During 1970–97, the direct method shows a cumulative balance of about −15 m, and the geodetic method shows a cumulative balance of about −22 m. The deviation between the two methods is fairly consistent, suggesting no gross errors in either, but rather a cumulative systematic error. It is suspected that the cumulative error is in the direct method because the geodetic method is based on a non-changing reference, the bedrock control, whereas the direct method is measured with reference to only the previous year's summer surface. Possible sources of mass loss that are missing from the direct method are basal melt, internal melt, and ablation on crevasse walls. Possible systematic measurement errors include under-estimation of the density of lost material, sinking stakes, or poorly represented areas. 相似文献