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361.
Gérard Thuillier Michel Hersé Paul C. Simon Dietrich Labs Holger Mandel Didier Gillotay Thomas Foujols 《Solar physics》1998,177(1-2):41-61
The SOLSPEC instrument has been built to carry out solar spectral irradiance measurements from 200 to 3000 nm. It consists of three spectrometers designed to measure the solar spectral irradiance in ultraviolet, visible, and infrared domains. It flew with the ATLAS I mission in March 1992. This paper is dedicated to the visible part of the solar spectrum. Comparisons with recent data are shown and differences below 450 nm are discussed. 相似文献
362.
We refer to two papers by Goodman (1995, 1996) on the heating of the chromosphere by large-scale electric currents, and to our paper (Lorrain and Koutchmy, 1993) on magnetic elements. Goodman assumes that the dynamo that runs a magnetic element stops operating at t = 0. From then on, the magnetic field decays exponentially, and the induced currents heat the chromosphere. The time constants calculated by Goodman disagree with the observed values, possibly because he disregards the driving dynamo. Also, he assumes static conditions, but his magnetic force density appears suddenly when the dynamo stops, and it is about equal to the gravitational force density. The magnetic force acts downward and fluctuations in the current flowing through the magnetic element should induce vertical oscillations at the photosphere. This point should be investigated further. 相似文献
363.
Bimal Kanti Paul 《The Professional geographer》1998,50(3):287-301
On May 13, 1996, a disastrous tornado hit the Tangail district of Bangladesh, killing more than 700 people and causing extensive damage to homes, crops, and livestock. This paper explores and analyzes how tornado victims adjusted to this destruction. Data collected from two study sites show that victims received emergency assistance from people both in neighboring areas and from more distant areas, as well as from government agencies and non-governmental organizations (NGOs). At both sites, NGOs played the leading role in minimizing the hardships of victims through extraordinary disaster relief and rehabilitation efforts. Because of the extensive support received, the tornado victims were able to return to their “normal” lives very quickly. This study concludes with several recommendations to help cope with future tornado disasters. 相似文献
364.
Aspects of GLONASS Carrier-Phase Differencing 总被引:2,自引:0,他引:2
365.
Variations in the crustal structure beneath western Turkey 总被引:6,自引:0,他引:6
Paul Saunders Keith Priestley & Tuncay Taymaz 《Geophysical Journal International》1998,134(2):373-389
366.
367.
The ML 5.3 Épagny (French Alps) earthquake of 1996 July 15: a long-awaited event on the Vuache Fault
368.
David M. Pyle Tjeerd H. van Andel Panayiotis Paschos Paul van den Bogaard 《Quaternary Research》1998,49(3):280-286
A newly recognized 2-m-thick trachytic volcanic ash deposit from northwestern Greece is dated at 374,000 ± 7000 yr and correlated with the Middle Pleistocene volcanic activity of central Italy. The deposit represents ash fallout from one of the largest volcanic eruptions in Europe of the past 400,000 yr and should provide an important stratigraphic marker within the poorly dated Middle Pleistocene deposits of Italy and Greece. 相似文献
369.
Paul F. Hudak 《Ground Water Monitoring & Remediation》1998,18(2):93-96
A graphical method was devised for designing contaminant detection monitoring networks in aquifers. The approach eliminates bias in detection efficiency among well pairs, thereby improving the overall efficiency of a ground water monitoring network. In the equidistant configurations derived by the graphical approach, all wells are located the same distance from a landfill, but the distance is measured parallel to ground water flow, Measured perpendicular to ground water flow, there is also an equal spacing between wells in an equidistant network. A simulation model was used to compare an equidistant network to a peripheral monitoring configuration, in which wells were spaced evenly along the downgradient boundaries of a landfill. The equidistant network yielded a 12.4% higher detection efficiency and also facilitated earlier release detection. In practice, the graphical approach that yields equidistant configurations can be used to identify candidate monitoring networks to detect potential releases from landfills. 相似文献
370.
Xenolith assimilation has been simulated with experiments involving melting wax spheres into hot water and aqueous solutions
and characterised by a theoretical analysis. Both the cases of neutrally buoyant stationary spheres and spheres sinking through
the hot host fluid are examined. Melt generated on a sphere's surface flows (compositional convection) in two regimes; as
a sheet over one hemisphere and then detaching as finger plumes from the other. Positional variations in the melting rate
are dominantly controlled by differences in the melt layer thickness which influence the thermal gradient and heat flux across
the layer. The theoretical model predicts melt layer thicknesses and the heat flux from the surrounding fluid. Calculated
melting rates agree well with experimental measurements. Partial melting of non-eutectic compositions produces a layer of
crystal-melt mush at the xenolith's surface. The theoretical analysis is extended to account for variation in rheological
properties across the mush layer. When stoped into typical magmas, xenoliths of common continental crust lithologies are predicted
to melt at rates in the order of 2 mm/hour. Thicknesses of the mobile mush layer around xenoliths are predicted to be typically
a few centimetres. Relatively mafic lithologies can melt quicker than silicic compositions because, although they are typically
more refractory, their lower melt viscosities result in thinner mush layers and so higher heat fluxes. Especially quick melting
of water-saturated lithologies occurs as a consequence of both the reduction in melting temperatures and melt viscosities.
Due to hot ambient conditions in the lower continental crust the assimilation of xenoliths into underplated basaltic magma
can be very rapid. For granulites and mafic-granulites the predicted melting rates are up to 17 mm/hour. Fast rates of melting
and efficient mixing of melt into the host magma indicate that assimilation of xenoliths will have a significant influence
on the compositional and thermal evolution of magmas.
Received: 7 November 1996 / Accepted: 5 January 1998 相似文献