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801.
We determine cosmological and evolutionary parameters from the 3CR K -band Hubble diagram and K -band number counts, assuming that the galaxies in question undergo pure luminosity evolution. Separately the two data sets are highly degenerate with respect to choice of cosmological and evolutionary parameters, but in combination the degeneracy is resolved. Of models that either are flat or have ΩΛ =0 , the preferred ones are close to the canonical case Ωcold matter =1 , ΩΛ =0 , with luminosity evolution amounting to 1 mag brighter at z =1 . 相似文献
802.
中国大陆现今垂直形变特征的初步探讨 总被引:25,自引:13,他引:12
利用GPS观测资料进行大范围的垂直形变特征研究是本文研究的重点。通过网络工程基准站和基本站的GPS观测资料,绘制了中国大陆的垂直速率等值线图像,并对中国大陆垂直运动特征进行了定性的分析,结果表明:中国大陆垂直运动在70%以上的区域表现为沉降运动,在青藏高原和除北京外的整个华北块体及燕山块体的垂直运动表现为隆升的趋势。中国大陆西北和东南、西南和东北的整体垂直运动呈一种斜对称状态。对基于GPS观测所得的等值线图与基于水观测所得的等值线图进行了比较,比较结果显示,除了华南块体外,二者在整体趋势上比较一致。 相似文献
803.
Deep and high-resolution radio observations of the Hubble Deep Field and flanking fields have shown the presence of two distant edge-darkened FR I radio galaxies, allowing for the first time an estimate of their high-redshift space density. If it is assumed that the space density of FR I radio galaxies at is similar to that found in the local Universe, then the chance of finding two FR I radio galaxies at these high radio powers in such a small area of sky is < 1 per cent. This suggests that these objects were significantly more abundant at than at present, effectively ruling out the possibility that FR I radio sources undergo no cosmological evolution. We suggest that FR I and FR II radio galaxies should not be treated as intrinsically distinct classes of objects, but that the cosmological evolution is simply a function of radio power with FR I and FR II radio galaxies of similar radio powers undergoing similar cosmological evolutions. Since low-power radio galaxies have mainly FR I morphologies and high-power radio galaxies have mainly FR II morphologies, this results in a generally stronger cosmological evolution for the FR IIs than the FR Is. We believe that additional support from the V / V max test for evolving and non-evolving population of FR IIs and FR Is respectively is irrelevant, since this test is sensitive over very different redshift ranges for the two classes. 相似文献
804.
We present upper limits on the 850-μm and 450-μm fluxes of the warm hyperluminous (bolometric luminosity galaxies IRAS P09104+4109 and IRAS F15307+3252 , derived from measurements using the SCUBA bolometer array on the James Clerk Maxwell Telescope. Hot luminous infrared sources like these are thought to differ from more normal cold ultraluminous infrared galaxies in that they derive most of their bolometric luminosities from dusty active galactic nuclei (AGNs) as opposed to starbursts. Such hot, dusty AGNs at high redshift are thought to be responsible for much of the mass accretion of the Universe that is in turn responsible for the formation of the supermassive black holes seen in the centres of local galaxies. The galaxy IRAS P09104+4109 is also unusual in that it is a cD galaxy in the centre of a substantial cooling-flow cluster, not an isolated interacting galaxy like most ultraluminous infrared galaxies. Previously it was known to have large amounts of hot dust from IRAS observations. We now show that the contribution of cold dust to the bolometric luminosity is less than 3 per cent. Most ultraluminous infrared galaxies possess large amounts of cold dust, and it is now known that some cooling-flow cluster cD galaxies do as well. Yet this object, which is an extreme example of both, does not have enough cold gas to contribute significantly to the bolometric luminosity. We outline physical reasons why this could have happened. We then provide a discussion of strategies for finding hot dusty AGNs, given the limitations on submillimetre surveys implied by this work. 相似文献
805.
CO2的地质埋存与资源化利用进展 总被引:18,自引:0,他引:18
把CO2注入油气藏、煤层提高油气采收率的方法(CO2-EOR、CO2-EGR、CO2-ECBM),因其在提高石油、天然气和煤层气采收率的同时,又能使一部分CO2永久地埋存于地下,实现油气增产和CO2减排的双赢效果,而成为当今CO2减排最具潜力的现实选择.CO2-EOR(Enhanced Oil Recovery)方法适用于油田开发晚期,通过把CO2注入到比较稳定的油藏,一般可提高油藏采收率达10%~15%;另外把CO2注入到气田中,实施CO2-EGR(Enhanced Gas Recovery).一方面,接近枯竭的气田在没有地层水入侵之前具有巨大的埋存能力,为CO2提供巨大的埋存空间;另一方面注入CO2后,使地层重新增压保持储层中原始的压力,可以保持储层的完整性和安全性.同时,原有的油气圈闭可作为良好的埋存箱能有效地阻止CO2泄漏,使部分CO2能永久地埋存于地下.此外,也可以把CO2注入到煤层中,实施CO2-ECBM(Enhanced Coalbed Methane Recovery),利用煤层对CO2和煤层气(主要为甲烷)吸附能力的差异,实现CO2排替CH4,提高CH4的采收率. 相似文献
806.
B. Mishra C.S. Saravanan A. Bhattacharya S. Goon S. Mahato H.J. Bernhardt 《Gondwana Research》2007,11(4):504-515
A combined fluid inclusion and mineral thermobarometric study in groups of synchronous inclusions in quartz within weakly foliated granites from the Chottanagpur Gneissic Complex, India, reveals super dense carbonic (CO2 with minor CH4 and H2O) inclusions and hypersaline (H2O–NaCl ± NaHCO3) inclusions, with halite- and nahcolite daughter phases. This study documents the highest density (1.115 g cm− 3) CO2 fluids ever reported in granites. Fluid isochores, constructed from CO2 (± CH4) and halite-bearing inclusions, coupled with two-feldspar thermometry constrain the minimum P–T at 8 kbar/ 750 °C for fluid entrapment in granites. By contrast, the carbonic inclusions in quartz from granite-hosted metapelite enclaves contain substantial CH4 (up to 30 mol%), and the entrapment pressure ( 4.3 kbar/600 °C) is considerably lower compared to those in the granites. By implication, the sillimanite-free granites were not derived from the metapelitic enclaves, and instead were formed by partial melting of fluid-heterogeneous lower crustal protoliths, with fluid entrapment at magmatic conditions. 相似文献
807.
TAO Zhen SHEN ChengDe GAO QuanZhou SUN YanMin YI WeiXi & LI YingNian School of Geography Planning Sun Yat-sen University Guangzhou China Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China Northwest Plateau Institute of Biology Chinese Academy of Sciences Xining China 《中国科学D辑(英文版)》2007,50(7)
High-resolution sampling,measurements of organic carbon contents and 14C signatures of selected four soil profiles in the Haibei Station situated on the northeast Tibetan Plateau,and application of 14C tracing technology were conducted in an attempt to investigate the turnover times of soil organic car-bon and the soil-CO2 flux in the alpine meadow ecosystem. The results show that the organic carbon stored in the soils varies from 22.12×104 kg C hm-2 to 30.75×104 kg C hm-2 in the alpine meadow eco-systems,with an average of 26.86×104 kg C hm-2. Turnover times of organic carbon pools increase with depth from 45 a to 73 a in the surface soil horizon to hundreds of years or millennia or even longer at the deep soil horizons in the alpine meadow ecosystems. The soil-CO2 flux ranges from 103.24 g C m-2 a-1 to 254.93 gC m-2 a-1,with an average of 191.23 g C m-2 a-1. The CO2 efflux produced from microbial decomposition of organic matter varies from 73.3 g C m-2 a-1 to 181 g C m-2 a-1. More than 30% of total soil organic carbon resides in the active carbon pool and 72.8%―81.23% of total CO2 emitted from or-ganic matter decomposition results from the topsoil horizon (from 0 cm to 10 cm) for the Kobresia meadow. Responding to global warming,the storage,volume of flow and fate of the soil organic carbon in the alpine meadow ecosystem of the Tibetan Plateau will be changed,which needs further research. 相似文献
808.
Z. Schenková V. Schenk I. Kalogeras R. Pichl P. Kottnauer C. Papatsimba G. Panopoulou 《Journal of Seismology》2007,11(3):345-353
Macroseismic intensity, a useful measure of earthquake effects, is still applied in a wide range of seismological applications
like seismic hazard assessments, attenuation relationships, etc. Isoseismals represent the spatial distribution of macroseismic
intensities, and their shapes depend on source properties, lithosphere structures, tectonic line orientations, site geology,
and topography. The applications ask for both the higher number of isoseismal maps, and their standardization and homogenization.
The point kriging gridding method for an automatic computer drawing of isoseismal maps was delivered. Smoothing rates and
numerical parameters used in the kriging algorithm were tested on macroseismic data of Greek earthquakes representing different
tectonic and geomorphological regimes. The optimum kriging default option was defined. Its application for four Greek earthquakes
is presented and discussed from the viewpoint of a broad use in recent macroseismology.
The online version of the original article can be found at . 相似文献
809.
The recent (25 years) morphodynamics of a proglacial reach of the Ridanna Creek, North‐East Italy, evolving in the absence of human constraints, has been investigated by means of an intensive field activity and of the analysis of aerial photographs. The study reach mostly displays a braided morphology, with sharp downstream variations of valley gradient, sediment size and formative conditions within the main channel. These discontinuities are associated with different processes of channel adjustment at different timescales, which have been quantified by coupling hydrological with morphological information. Several processes of channel change and variations in braiding intensity have been documented along the whole reach and highlight how a regular, weakly meandering main channel may significantly affect the morphodynamics of the braided network. A first attempt to predict the morphological instability of this main channel at the observed spatial scales through existing linear theories of curved river channels shows a good agreement with field observations. Finally, the complete hydro‐morphodynamical characterization of such an undisturbed alpine river reach can provide a relevant contribution to the definition of reference conditions for Alpine rivers required by the EU Water Framework Directive. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
810.
一次大范围一氧化碳中毒事件的气象条件 总被引:1,自引:0,他引:1
冬季是燃煤居民一氧化碳中毒的多发季节。针对2006年2月13—16日发生在吉林省延边州罕见的大范围一氧化碳中毒事件,从大尺度环境条件、气象要素变化特征及与燃煤烟道排烟关系等方面进行了分析。分析延吉近46年冬季(1960—2005年11月-2月)气象观测资料,发现“2.13”一氧化碳中毒事件是在近地面出现强烈逆温、最大逆温层顶高度低、地面接近静风、同时气温明显回升、气压明显下降等气象条件下发生的。此气象要素组合在历史上实属罕见。一氧化碳中毒事件不是某单一气象要素决所定的,而是众多气象要素组合综合作用的结果。 相似文献