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Parameters of the distant galaxy clusters of 3C295 (z=0.46) and Cl 0024+1654 (z=0.39) are compared with the predictions made using galaxies of the local clusters Coma (z=0.023) and DC 0329–52 (z=0.057) taking theK-effect into account. The distributions of colour and morphological type, and the amplitudesF
+/F– of the 0 4000 discontinuity are examined and no evidence for evolution of the galaxies and the clusters can be seen. 相似文献
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Leena Järvi Ari-Juhani Punkka David M. Schultz Tuukka Petäjä Harri Hohti Janne Rinne Toivo Pohja Markku Kulmala Pertti Hari Timo Vesala 《Boundary-Layer Meteorology》2007,125(2):343-359
On the afternoon of 3 July 2004 in Hyytiälä (Juupajoki, Finland), convective cells produced a strong downburst causing forest damage. The SMEAR II field station, situated near the damage site, enabled a unique micrometeorological analysis of a microburst with differences above and inside the canopy. At the time of the event, a squall line associated with a cold front was crossing Hyytiälä with a reflectivity maximum in the middle of the squall line. A bow echo, rear-inflow notch, and probable mesovortex were observed in radar data. The bow echo moved west-north-west, and its apex travelled just north of Hyytiälä. The turbulence data were analysed at two locations above the forest canopy and at one location at sub-canopy. At 1412 EET (Eastern European Time, UTC+2), the horizontal and vertical wind speed increased and the wind veered, reflecting the arrival of a gust front. At the same time, the carbon dioxide concentration increased due to turbulent mixing, the temperature decreased due to cold air flow from aloft and aerosol particle concentration decreased due to rain scavenging. An increase in the number concentration of ultra-fine particles (< 10 nm) was detected, supporting the new particle formation either from cloud outflow or due to rain. Five minutes after the gust front (1417 EET), strong horizontal and downward vertical wind speed gusts occurred with maxima of 22 and 15 m s?1, respectively, reflecting the microburst. The turbulence spectra before, during and after the event were consistent with traditional turbulence spectral theory. 相似文献
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Eija Honkavaara Eero Ahokas Juha Hyypp Juha Jaakkola Harri Kaartinen Risto Kuittinen Lauri Markelin Kimmo Nurminen 《ISPRS Journal of Photogrammetry and Remote Sensing》2006,60(6):387
Test field system calibration will be a fundamental part of the future photogrammetric production line. Accurate calibration and performance evaluations are necessary for fully assessing the stability and accuracy of digital sensing techniques. In this paper, a method of comprehensive geometric calibration in a test field has been developed and empirically tested using eight image blocks collected with three UltraCamD digital large format photogrammetric cameras. Permanent photogrammetric test fields form the basis of the method. Important components of the method are determination of system parameters, evaluation of systematic errors, and assessment of geometric accuracy. The results showed that UltraCamD images contained systematic deformations that could not be modeled with single lens additional parameter models. Good point determination accuracy was obtained despite the systematic errors; the typical accuracy was 2–3 μm in image space in the horizontal coordinates and 0.05–0.09‰ of the object distance in height. One of the cameras had significantly poorer performance. In the worst cases, the horizontal accuracy was 5 μm in image space and the height accuracy was 0.18‰ of the object distance. The analog cameras gave better results than the UltraCamD, but the development of appropriate mathematical models for UltraCamD as well as improvements in digital sensors may change the situation in the near future. 相似文献
4.
Observations of quasars suggest that compact quasars with flat radio spectra belong to the class of dwarf galaxies and extended quasars with steep spectra to the one of bright galaxies. This can be seen also in the associations of quasars with clusters of galaxies, compact quasars occurring in nearby clusters and extended quasars in distant clusters. 相似文献
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Latitude-velocity contour maps given by Schober (1976) for the low-velocity neutral hydrogen show a significant correlation
between these parameters. The result can be interpreted either by a contraction of the local Hi cloud in the galacticz-direction, or by a non-Dopplerian red shift in a medium associated with the galactic disk. 相似文献
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A collection of subfossil specimens of Discinisca tenuis from Lüderlitz, Namibia was studied by means of the X-ray diffraction (XRD) technique. Using the whole-pattern fitting procedure refined by the authors, the unit cell dimensions, crystallite dimensions, and number of strains were detected. Post-mortality alterations in shell apatite are related to mineral component content ranging from 69 to 82% in subfossil shells, as compared to 68% in shells of living species. It has been established that the lattice parameter a decreases from 9.380 to 9.370 Å, while parameter c is less involved during the decomposition of organic matter. The post-mortality alteration is assumed to proceed by the subsequent recrystallization of shell apatite. Consequently, primarily elongated hexagonal prisms (150 × 370 Å) turn to smaller ones (120 × 260 Å), and the number of strains tends to increase. 相似文献
10.
Toivo Korja 《Surveys in Geophysics》2007,28(2-3):239-272
I review recent investigations on the electrical conductivity of the lithosphere and asthenosphere in Europe. The principal
method in the reviewed studies is the magnetotelluric method, but in many cases other electromagnetic methods (e.g., magnetovariational
profilings and geomagnetic depth soundings) have provided additional information on subsurface conductivity or have been the
primary method. The review shows that the magnetotelluric method has been used, and is being used, in all kinds of environments
and for many different processes shaping the crust and lithosphere. The crust is very heterogeneous, both with respect to
the scale of conductive/resistive features and interpretations: research targets vary from Archaean palaeostructures to ongoing
processes. The European database of the depth to the lithosphere-asthenosphere boundary (LAB) in Europe is updated, and a
new map showing lateral variations of the depth of LAB is provided. The compilation shows that (1) the Phanerozoic European
lithosphere, with considerable variations (45–150 km), is much thinner than the Precambrian European lithosphere, (2) the
Trans-European Suture Zone is a major electrical border in Europe separating electrically (as well as geophysically and geologically
in general) two quite different settings, (3) the thinnest lithosphere is found under the extensional Pannonian Basin (45–90 km),
(4) in most of the East European Craton there are no indications of a high conductivity zone in upper mantle. In many regions
there is no information at all on upper mantle conductivity, which calls for pan-European projects to operate arrays of simultaneously
recording instruments with long recording periods (2–8 months) and dense spatial sampling (20–50 km). 相似文献