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151.
152.
Spherical harmonic expansions of the geopotential are frequently used for modelling the earth’s gravity field. Degree and
order of recently available models go up to 360, corresponding to a resolution of about50 km. Thus, the high degree potential coefficients can be verified nowadays even by locally distributed sets of terrestrial gravity
anomalies. These verifications are important when combining the short wavelength model impact, e.g. for regional geoid determinations
by means of collocation solutions. A method based on integral formulae is presented, enabling the improvement of geopotential
models with respect to non-global distributed gravity anomalies. To illustrate the foregoing, geoid computations are carried
out for the area of Iran, introducing theGPM2 geopotential model in combination with available regional gravity data. The accuracy of the geoid determination is estimated
from a comparison with Doppler and levelling data to ±1.4m. 相似文献
153.
Rachel Mundeli Murekatete 《International journal of geographical information science》2018,32(11):2169-2188
Planners who are involved in locational decision-making often use raster-based geographic information systems to quantify the value of land in terms of suitability or cost for a certain use. From a computational point of view, this process can be seen as a transformation of one or more sets of values associated with a grid of cells into another set of such values through a function reflecting one or more criteria. While it is generally anticipated that different transformations lead to different ‘best’ locations, little has been known on how such differences arise (or do not arise). The paper attempts to answer this question in the context of path planning through a series of computational experiments using a number of random landscape grids with a variety of spatial and nonspatial structures. In the experiments, we generated least-cost paths on a number of cost grids transformed from the landscape grids using a variety of transformation parameters and analyzed the locations and (weighted) lengths of those paths. Results show that the same pair of terminal cells may well be connected by different least-cost paths on different cost grids though derived from the same landscape grid and that the variation among those paths is affected by how given values are distributed in the landscape grid as well as by how derived values are distributed in the cost grids. Most significantly, the variation tends to be smaller when the landscape grid contains more distinct patches of cells potentially attracting or distracting cost-saving passage or when the cost grid contains a smaller number of low-cost cells. 相似文献
154.
155.
The study aimed to determine, by using a statistical model, the effect of weather conditions on the incidence of Lophodermium yellow needle blight causing by new species for science- Lophodermium corconticum, in the mountain dwarf pine growing in the subalpine Karkonosze Mountains and the Izerskie Mountains(Poland). Needles showed symptoms of yellow spots, gradual discolouration and premature fall in July. The assessment of healthiness of infected mountain dwarf pine needles spanned three years(2011- 2013) and was conducted in several test sites in the Karkonosze and Izerskie Mountains. The results were analyzed by taking into account the meteorological conditions. Field observations seem to indicate that the highest infestation of mountain dwarf pine occurs in June and July, while September and October see a significantly lower disease index in the Karkonosze Mountains. The lower indices of the infestation of mountain dwarf pine are characteristic for the vegetation in the Hala Izerska high mountain pasture; whereas the environmental conditions prevailing in the Kocio? Ma?ego Stawu cirque and above the Samotnia hostel are conducive to the development of Lophodermium yellow needle blight. 相似文献
156.
Priv.-Doz. Dr. Max Weber 《Pure and Applied Geophysics》1961,49(1):1-12
Zusammenfassung Es wird eine Approximation von Laufzeitfunktionen aus diskreten Messwerten mit abgebrochenen Potenzreihen behandelt. Zur bequemen Anwendung werden Tabellen berechnet. Der Beitrag schliesst mit einem Beispiel aus der Praxis.
Summary An approximation to travel-time functions by restriced power series is treated. For numerical computations convenient tables are calculated and an example is given.相似文献
157.
H. Weber 《Aquatic Sciences - Research Across Boundaries》1932,6(1-2):105-127
Ohne Zusammenfassung 相似文献
158.
J. Jacobs W. Bauer G. Spaeth R. J. Thomas K. Weber 《International Journal of Earth Sciences》1996,85(4):800-821
The Heimefrontfjella mountains, Western Dronning Maud Land (East Antarctica), are dominantly composed of Grenville-aged (≈
1.1 Ga) rocks, which were reworked during the Pan -African orogeny at ≈500 Ma. Three discontinuity-bounded Grenville-aged
terranes have been recognized namely (from north to south) the Kottas, Sivorg and Vardeklettane terranes. The terranes contain
their own characteristic lithological assemblages, although each is made up of an early supracrustal sequence of metavolcanic
and/or metasedimentary gneisses, intruded by various (predominantly granitoid) suites. No older basement upon which the protoliths
of these older gneisses were deposited has been recognized. In each terrane the older layered gneisses were intruded by various
plutonic suites ranging in age from ≈ 1150 to ≈1000 Ma. The Vardeklettane terrane is characterized by abundant charnockites
and two-pyroxene granulite facies parageneses in metabasites, whereas the Sivorg and Kottas terranes were metamorphosed to
amphibolite facies grade. P-T estimates show that peak metamorphic conditions changed from ≈600°C at 8 kbar in the south,
to ≈700 °C at 4 kbar in the northern Sivorg terrane. Regional greenschist retrogression of high-grade assemblages may be of
Pan-African age. The Heimefrontfjella terranes were juxtaposed and pervasively deformed during a complex and protracted period
of E-W collision orogenesis in a transpressive regime at ≈ 1.1 Ga. This is manifest as early, gently dipping thrust-related
shear fabrics (D1), succeeded by the initiation of an important (D2) steep dextral shear zone (Heimefront shear zone, HSZ), during which the early fabrics and structures were steepened and
rotated in an anticlockwise sense. The HSZ is a curvilinear structure which changes from a dextral oblique strike-slip lateral
ramp in the north to a steep dip-slip frontal ramp in the south, where it forms the boundary between the Sivorg and Vardeklettane
terranes. The Pan-African event is manifested as discrete, low- to medium-temperature ductile to brittle shears (D3) and numerous K/Ar cooling ages. 相似文献
159.
Jon N Weber 《Geochimica et cosmochimica acta》1973,37(9):2173-2190
Two thousand and twenty well-characterized coral specimens from 17 localities have been analyzed for Sr. Seventy-three genera and subgenera, mostly hermatypic scleractinians, are represented. For some genera, specimens living in surface reef environments are compared with those from 18.3 m depths on the same reefs. Growth rates for some species have also been measured at these depths at one of the sampling sites. Skeletal strontium for a given genus decreases with increasing water temperature, a relationship which previously eluded detection. Aragonite deposited by corals living on the reef at a depth of 18.3 m contains more strontium than the skeletal aragonite of the same coral genera from shallow-water, surface environments. Quantitative treatment of the data for Acropora, one of the most abundant and widely distributed of the reef-building corals, suggests that the observed strontium variations may reflect variations in the rate of skeletal calcification, rather than direct dependence upon temperature or water depth. There is evidence for ‘species effects’, apparently unrelated to growth rate differences, in that certain coral genera are consistently enriched or depleted in skeletal strontium content relative to other genera living in the same reef environments under identical ambient conditions. Temperature, salinity, water depth, seawater composition, and/or other such parameters may in part determine the levels of trace element concentration in carbonates deposited by corals and other marine invertebrates, but it would appear that these variables more directly affect physiological processes which in turn control skeletal chemistry. 相似文献
160.
Rachel?M.?Weber Paul?J.?WallaceEmail author A.?Dana Johnston 《Contributions to Mineralogy and Petrology》2012,163(5):825-840
High-Mg basaltic andesites and andesites occur in the central trans-Mexican volcanic belt, and their primitive geochemical
characteristics suggest equilibration with mantle peridotite. These lavas may represent slab melts that reequilibrated with
overlying peridotite or hydrous partial melts of a peridotite source. Here, we experimentally map the liquidus mineralogy
for a high-Mg basaltic andesite (9.6 wt% MgO, 54.4 wt% SiO2, Mg# = 75.3) as a function of temperature and H2O content over a range of mantle wedge pressures. Our results permit equilibration of this composition with a harzburgite
residue at relatively high water contents (>7 wt%) and low temperatures (1,080–1,150°C) at 11–14 kbar. However, in contrast
to the high Ni contents characteristic of olivine phenocrysts in many such samples from central Mexico, those of olivine phenocrysts
in our sample are more typical of mantle melts that have fractionated a small amount of olivine. To account for this and the
possibility that the refractory mantle source may have had olivine more Fo-rich than Fo90, we numerically evaluated alternative equilibration conditions, using our starting bulk composition adjusted to be in equilibrium
with Fo92 olivine. This shifts equilibration conditions to higher temperatures (1,180–1,250°C) at mantle wedge pressures (11–15 kbar)
for H2O contents (>3 wt%) comparable to those analyzed in olivine-hosted melt inclusions from this region. Comparison with geodynamic
models shows that final equilibration occurred shallower than the peak temperature of the mantle wedge, suggesting that basaltic
melts from the hottest part of the wedge reequilibrated with shallower mantle as they approached the Moho. 相似文献