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21.
Measurements of salinity perturbations in a partially mixed estuary have been used to evaluate the usefulness of an inductive salinometer and to determine some of the characteristics of the salinity perturbations. The salinometer performed satisfactorily under most conditions. Although internal wave like effects were present, the turbulence fluctuations were dominant. The salinity fluctuations and the turbulent fluxes and were found to behave in a manner similar to the density fluctuations in a thermally stratified atmospheric boundary layer and a laboratory open channel flow. A quadrant analysis suggested that the contribution of each quadrant to the turbulent flux changed with Ri. The turbulence parameters ν and cγ were found to decrease and increase respectively as Ri increases. 相似文献
22.
秦岭凤太矿田层控铅锌(铜)矿床的金属物质、硫和成矿溶液主要来自深部基底的岩石,属海底喷流—沉积成因矿床。从这一理论认识出发可进一步分析控矿地质条件及今后在该区有效地寻找同类矿床。 相似文献
23.
Long-wavelength S-wave velocity structure throughout the mantle 总被引:4,自引:0,他引:4
Toshiro Tanimoto 《Geophysical Journal International》1990,100(3):327-336
24.
《中国地理科学(英文版)》2004,14(4):296-303
1INTRODUCTIONUrbanrelationshipaswellasurbansystemhas beenthemostimportantandlastingdirectioninthestudyofur-bangeographysinceCHRISTALLER(1933)putfor-wardthecentralplacetheory.Alongwiththepaceofglobalizationinthe1980s,somepioneer researchessen-sitivelyexpoundedaworldcitysystem,includingworldcity,internationalcity,nationalcity,regionalcityandlocalcity(FRIEDMAN,1986).Lotsofresearchesfo-cusedonthedevelopingmechanismofthebigcitiesandurbansystemnetwork(GU,2000;ZHOU,1997;CUI,1992;HUeta… 相似文献
25.
V. Castellani S. Degl'Innocenti P. G. Prada Moroni 《Monthly notices of the Royal Astronomical Society》2001,320(1):66-72
We compare theoretical stellar models for main sequence (MS) stars with the Hipparcos data base for the Hyades cluster to give a warning against the uncritical use of available theoretical scenarios and to show how formal MS fittings can be fortuitous if not fictitious. Moreover, we find that none of the current theoretical scenarios appears able to account for an observed mismatch between theoretical predictions and observations of the coolest Hyades MS stars. Finally, we show that current theoretical models probably give too faint He burning luminosities unlike the case of less massive He burning models, with degenerate progenitors, which have been suggested to suffer the opposite discrepancy. 相似文献
26.
We investigate the evolution of rotation period and spindown age of a pulsar whose surface magnetic field undergoes a phase
of growth. Application of these results to the Crab pulsar strongly indicates that its parameters cannot be accounted for
by the field growth theories. 相似文献
27.
Sunetra Giridhar N. Kameswara Rao David L. Lambert 《Journal of Astrophysics and Astronomy》1996,17(1-2):23-40
Two high resolution spectra of the hot RCrB star DY Cen in the red region are compared. The photospheric absorption lines
show a radial velocity variation of 12 kms-1 between 1989 July and 1992 May. Emission components to some CII lines present
in 1989 are almost entirely absent in 1992. Nebular forbidden lines of [OI], [NII] and [SII] appear unchanged from 1989 to
1992 相似文献
28.
Natural and agricultural wetlands are considered to be the major sources of global atmospheric methane (CH4). A one‐dimensional model was developed to simulate methane emission and used to examine the influence of various physical processes on the rate of methane emission. Three processes involved in the methane emission are implemented in the model: production, reoxidation and transport. Three transport pathways were considered: diffusion across water–air or soil–air interfaces, ebullition and diffusion through plants. These pathways are influenced by soil properties, plant growth, water‐table conditions, temperature and external inputs (e.g. fertilizer). The model was used to examine the seasonal variation of the methane emission at a rice field in Hunan, China, which was observed during a field experiment for consecutive (early and late) rice seasons in 1992. The observed seasonal variations of methane emission, and role of plants in transporting methane to the atmosphere, are captured by the model simulation. Further model applications were conducted to simulate effects of fertilizer and water‐level condition on the methane emission. The results indicate that unfermented organic fertilizer produces a higher methane emission rate than mineral fertilizer. The simulations with treatments of a deep‐water covering and constant moisture reduced the methane emission. The rice field study provides a framework for further development of the model towards simulations based on spatially distributed variables (e.g. water table, soil temperature and vegetation) at a regional scale. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
29.
30.
Martin M. Roth Thomas Fechner Dieter Wolter Andreas Kelz Thomas Becker 《Experimental Astronomy》2002,14(2):99-105
PMAS, the Potsdam Multi-Aperture Spectrophotometer, is a new integral field spectrograph in the optical, which is optimized
for good transmission and high image quality from 350 nm to 1 μm. We present our plan to implement a CCD charge-shuffle mode
to allow for beam switching with a very high degree of sky subtraction accuracy for faint object 3-D spectroscopy.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献