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排序方式: 共有117条查询结果,搜索用时 484 毫秒
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Rebecca E. Eager Sethu Raman Teddy R. Holt Douglas Westphal Jeffrey Reid Jason Nachamkin Ming Liu Abdulla Al Mandoos 《Pure and Applied Geophysics》2007,164(8-9):1747-1764
A statistical evaluation of the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS®) was performed over the Arabian Gulf region for the period, 1 August to 5 October, 2004. Verification skill scores of bias and root-mean-square error were estimated for surface variables and for vertical profiles to investigate any diurnal variations. The model predictions of boundary-layer heights are compared with the observations at Abu Dhabi, United Arab Emirates. The Middle East presents challenges to numerical weather prediction due to complex land-ocean-land mesoscale processes. An independent data set of surface measurements from 50 stations in the UAE was available from the Department of Water Resources Studies, Abu Dhabi for model verification. The results indicate a diurnal variation in the model errors. The errors are small considering the magnitudes of the observed variables. Errors in the coastal region can be attributed to the differences in the timing of the onset of sea and land breeze circulations in the simulations as compared to the observations. Errors are relatively smaller in the offshore locations. 相似文献
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G.J.G. Upton A.R. Holt R.J. Cummings A.R. Rahimi J.W.F. Goddard 《Atmospheric Research》2005,77(1-4):300
Microwave links are ideally suited to the urban environment, since there are many suitable vandal-free locations to which the receiver and transmitter can be attached. A signal sent along a link is received with reduced power as a consequence of scattering and absorption by intervening water droplets. Thus a measurement of the power loss can be transformed into a measure of total path rainfall. This paper discusses the requirements for the estimation process to be accurate. The paper presents results using a single frequency, together with the improved results from a dual-frequency link. Potential future applications of microwave links are presented. 相似文献
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U. Hwang R. Petre A. E. Szymkowiak S. S. Holt 《Journal of Astrophysics and Astronomy》2002,23(1-2):81-87
We present a newChandra observation of Tycho’s supernova remnant with the Advanced CCD Imaging Spectrometer. Multicolor Xray imaging reveals new
details of the outer shock and ejecta. At energies between 4 and 6 keV, the outline of the outer shock is clearly revealed
in X-rays for the first time. The distribution of the emission from lines of Si and Fe are confirmed to have a different morphology
from each other, and the Si ejecta are shown to extend to the blast shock at several locations. Characteristic spectra of
the outer shock and ejecta are also presented. 相似文献
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C.R. Benn M. Vigotti M. Pedani J. Holt K.-H. Mack R. Curran S.F. Sánchez 《Monthly notices of the Royal Astronomical Society》2002,329(1):221-226
In a pilot search for high-redshift radio quasi-stellar objects (QSOs), we have obtained spectra of 55 FIRST sources with very red starlike optical identifications. 10 of the candidates are QSOs with redshifts (four were previously known), six with . The remaining 45 candidates comprise: one broad-absorption-line (BAL) QSO; three low-redshift galaxies with narrow emission lines; 18 probable radio galaxies; and 23 M stars (mainly misidentifications). The success rate (high-redshift QSOs / spectroscopically-observed candidates) for this search is 1/2 for , and 1/9 for . With an effective search area of 4030 deg2 , the surface density of high-redshift QSOs discovered with this technique is 0.0015 deg−2 . 相似文献
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Can saltwater toxicity be predicted from freshwater data? 总被引:3,自引:0,他引:3
K M Leung D Morritt J R Wheeler P Whitehouse N Sorokin R Toy M Holt M Crane 《Marine pollution bulletin》2001,42(11):1007-1013
The regulation of substances discharged to estuarine and coastal environments relies upon data derived from ecotoxicity tests. Most such data are generated for freshwater rather than saltwater species. If freshwater toxicity data are related to saltwater toxic effects in a systematic and predictable way, the former can be used to predict the latter. This would have economic advantages due to a reduction in toxicity testing of saltwater species. If toxicity data are plotted as species sensitivity distributions, four theoretical relationships between freshwater and saltwater can be envisaged. Examples show that each one of these relationships is supported by empirical data. These examples show that although there is considerable potential for freshwater to saltwater prediction, species parity and representativeness need to be examined for each chemical substance to avoid bias. 相似文献