A global perspective on changing sustainable urban water supplies   总被引：12，自引：0，他引：12  

G. Darrel Jenerette  Larissa Larsen 《Global and Planetary Change》2006,50(3-4):202-211

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Southern high latitude climate anomalies associated with the Indian Ocean dipole mode     

刘娜贾贞  陈红霞华锋 《中国海洋湖沼学报》2006,24(2):125-128

1 INTRODUCTION In southern high latitudes, recent observations have shown a standing mode of ACW (Antarctic Circumpolar Wave) with eastward propagation across the Southern Ocean of the Antarctic in co- varying SST (sea surface temperature) and SLP (sea le…  相似文献   

The linear matching method for the shakedown analysis of geotechnical problems     

M. Boulbibane  A. R. S. Ponter 《国际地质力学数值与分析法杂志》2006,30(2):157-179

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Atmospheric variations and meteorite production on Mars     

John E. Chappelow  Virgil L. Sharpton 《Icarus》2006,184(2):424-435

Through a combination of aerobraking (drag deceleration) and ablation, meteoroids which enter planetary atmospheres may be slowed sufficiently to soft-land as meteorites. Results of an earlier study suggest that the current 6 mbar atmosphere of Mars is sufficient to aerobrake significant numbers of small (<10 kg) asteroidal-type meteoroids into survivable, low-velocity (<500 m s⁻¹) impacts with the planet's surface. Since rates of meteorite production depend upon the density of Mars's atmosphere, they must also change as the martian climate changes. However, to date, martian meteorite production has received relatively little attention in the literature Here we expand upon our previous work to study martian meteorite production rates and how they depend upon variations of the martian atmosphere, and to estimate the ranges of mass, velocity and entry-angle that produce meteorites. We find that even the current atmosphere of Mars is sufficient to soft-land significant fractions of incident stony and iron objects, and that these fractions increase dramatically for denser martian atmospheres. Therefore, like impact cratering, meteorite populations may preserve evidence of past martian climates.  相似文献   

也论二十世纪中国文学发展中的民间文化思潮——兼与高有鹏先生商榷     

李雄飞 《广东海洋大学学报》2006,26(5):79-83

文学思潮与民间文化都是具有特定内涵的严格概念，与其他思潮既有联系又有区别，民间文化因为自己特殊的存在状态和创造主体而形不成思潮，二十世纪中国文学发展中的五大运动都与民间文化有关，但是不能以民间文化思潮的面目出现。高有鹏先生的《论二十世纪中国文学发展中的民间文化思潮》命题不准确，文中尚有许多可以商榷之处。  相似文献   

Late Glacial fluvial response of the Niers‐Rhine (western Germany) to climate and vegetation change     

C. Kasse  W. Z. Hoek  S. J. P. Bohncke  M. Konert  J. W. H. Weijers  M. L. Cassee  R. M. Van Der Zee 《第四纪科学杂志》2005,20(4):377-394

The Niers valley was part of the Rhine system that came into existence during the maximum Saalian glaciation and was abandoned at the end of the Weichselian. The aim of the study was to explain the Late Pleniglacial and Late Glacial fluvial dynamics and to explore the external forcing factors: climate change, tectonics and sea level. The sedimentary units have been investigated by large‐scale coring transects and detailed cross‐sections over abandoned channels. The temporal fluvial development has been reconstructed by means of geomorphological relationships, pollen analysis and ¹⁴C dating. The Niers‐Rhine experienced a channel pattern change from braided, via a transformational phase, to meandering in the early Late Glacial. This change in fluvial style is explained by climate amelioration at the Late Pleniglacial to Late Glacial transition (at ca. 12.5 k ¹⁴C yr BP) and climate‐related hydrological, lithological and vegetation changes. A delayed fluvial response of ca. 400 ¹⁴C yr (transitional phase) was established. The channel transformations are not related to tectonic effects and sea‐level changes. Successive river systems have similar gradients of ca. 35–40 cm km^?1. A meandering river system dominated the Allerød and Younger Dryas periods. The threshold towards braiding was not crossed during the Younger Dryas, but increased aeolian activity has been observed on the Younger Dryas point bars. The final abandonment of the Niers‐Rhine was dated shortly after the Younger Dryas to Holocene transition. Traces of Laacher See pumice have been found in the Niers valley, indicating that the Niers‐Rhine was still in use during the Younger Dryas. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

新滩滑坡后两岸边坡的位移监测及形变趋势     

况仁杰  曹新菊  赵城  王尚庆  吴定洪 《大地测量与地球动力学》1993,(2)

本文介绍新滩滑坡后两岸边坡监测的工作,对边坡变形提出了趋势意见。认为新滩斜坡目前正处于整体稳定下的局部调整阶段,变形缓慢平稳,但要注视广家崖的危岩动态;链子崖仍有趋势性的倾江形变。5—6号缝围成的7万方危岩及江段的5万方危岩体尚有一触即崩之势,须加强监视。  相似文献   

Supereruptions as a Threat to Civilizations on Earth-like Planets     

Michael R. Rampino 《Icarus》2002,156(2):562-569

The largest explosive volcanic eruptions (supereruptions) produce >1000 km³ of ejected material and ≥1000 Mt (10¹⁵ g) of submicron atmospheric aerosols and dust. These eruptions may be capable of creating global climatic disturbances sufficient to cause severe problems for world agriculture and modern civilization. Supereruptions are estimated to occur on average about every 50,000 years, which is about twice the frequency of impacts by comets and asteroids ≥1 km diameter predicted to cause similar climatic effects. Prediction, prevention, and mitigation of global volcanic climatic disasters may be potentially more difficult than planetary protection from the threat of large impacts, so that explosive volcanism might limit the longevity of technological civilizations.  相似文献   

The Wiener–Levinson algorithm and ill-conditioned normal equations     

R. J. O'Dowd 《Geophysical Journal International》1991,106(2):399-406

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Effective properties of a cemented or an injected granular material     

A. Benhamida  F. Bouchelaghem  H. Dumontet 《国际地质力学数值与分析法杂志》2005,29(2):187-208

In this paper the macroscopic elastic properties of injected or cemented sands are derived from the characteristics of the constituents and the analysis of the microstructure using a multi‐scale modelling approach. Particular interest is given to the choice of the representative elementary volume, by relying on existing microstructural data. The periodic homogenization is adopted and required numerical solutions are performed by the finite element method. An assessment of the validity of the multi‐scale approach is achieved through comparison with theoretical and experimental results on cemented and injected granular media reported in the literature. The capabilities of the model are also used to investigate the influence of geometrical and mechanical microscale parameters on the macroscopic behaviour of the treated materials. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献