Modes to replace transitional asymptotic ray fields in a vertically inhomogeneous earth model     

E. Niver  A. Kamel  L. B. Felsen 《Geophysical Journal International》1985,80(2):289-312

Summary. Asymptotic ray theory (ART) fails in transition regions near critically reflected, bottom glancing or caustic-forming rays in a vertically inhomogeneous layered earth. These deficiencies are repaired here by replacing the transitional ray fields with guided modes plus truncation remainders. Exact ray-mode equivalences and their high-frequency asymptotic approximations are formulated, and their validity and efficiency are verified by numerical comparisons for SH motion in a two-layer earth model comprised of an inhomogeneous sediment above an homogeneous semi-infinite bedrock.  相似文献   

Self-similar solutions for the blast wave problem in radiative gasdynamics,I     

J. B. Singh  K. S. Singh 《Astrophysics and Space Science》1985,111(1):79-85

Similarity solutions, describing the flow of a perfect gas behind spherical shock waves, are investigated including the radiation heat flux. The shock is assumed to be propagating in a medium at rest. Shock radius varies exponentially with time and density is inversely proportional to fifth power of the shock radius immediately ahead of the shock front.  相似文献   

Mineral Resources of Chinese Altay and Tianshan： Metallogeny and Related Tectonic Processesm—A field workshop of IGCP-473     

MaoJingwen ReimarSeltmann RichardJ.Goldfarb 《《幕》》2004,27(1):44-47

A workshop of the IGCP-473 was held in Xinjiang, northwestern China, from August 9-21. It was attended by more than 70 scientists, including 29 from outside of China, i.eUnited States, Canada, Australia, Japan,Russia, United Kingdom, South Africa,Mongolia, Kyrgyzstan, and Khazakstan. The workshop was superbly organized by a team led by Prof. Mao Jingwen of Institute of  相似文献   

Aircraft Observation of CO₂, CO, O₃ and H₂ over the North Pacific during the PACE-7 Campaign     

Y. SAWA  H. MATSUEDA  Y. MAKINO  H. Y. INOUE  S. MURAYAMA  M. HIROTA  Y. TSUTSUMI  Y. ZAIZEN  M. IKEGAMI  K. OKADA 《Tellus. Series B, Chemical and physical meteorology》2004,56(1):2-20

  相似文献   

Equilibrium response of thermohaline circulation to large changes in atmospheric CO2 concentration     

R. J. Stouffer  S. Manabe 《Climate Dynamics》2004,22(2-3):325-326

  相似文献   

Friedmann cosmology with a cosmological constant in the modified Brans-Dicke theory     

A. Banerjee  N. Banerjee 《Astrophysics and Space Science》1985,114(1):165-174

Homogenous isotropic cosmologies in the presence of a cosmological constant A are studied in the modified Brans-Dicke theory. A class of exact solutions are obtained in Dicke's revised units for empty space as well as for the models filled with dust or radiation. Behaviour of these models near the singularity are discussed.  相似文献   

Oceanic Engineering: The making of an IEEE Society     

Coggeshall  I. 《Oceanic Engineering, IEEE Journal of》1985,10(2):63-83

In connection with the celebration of the centennial of the Institute of Electrical and Electronics Engineers (UEEE) in 1984, the history of electrical engineering in relation to the world's oceans is traced, with emphasis on the 20-year period from the 1960's to the present. Note is taken of the breadth of the cross-disciplinary interests involved, as exemplified by the active participation of a score of IEEE Societies and Professional Groups, how they organized to cooperate, the periodic meetings and annual conferences they sponsored, the publications they undertook, the tokens of recognition they adopted, and how they adapted to changes in emphasis to reflect shifts in the areas of technology served. Finally, an assessment is made of the future of the recently organized IEEE Oceanic Engineering Society.  相似文献   

Going underground: in search of Carboniferous coal forests     

Howard J. Falcon-Lang  William A. DiMichele  Scott Elrick  & W. John Nelson 《Geology Today》2009,25(5):181-184

The development of coal forests during the Carboniferous is one of the best-known episodes in the history of life. Although often reconstructed as steamy tropical rainforests, these ancient ecosystems were a far cry from anything we might encounter in the Amazon today. Bizarre giant club-mosses, horsetails and tree ferns were the dominant plants, not flowering trees as in modern rainforests. At their height, coal forests stretched all the way from Kansas to Kazakhstan, spanning the entire breadth of tropical Pangaea. Most of what we know of their biodiversity and ecology has been quite literally mined out of the ground through two centuries of hard labour. Without coal mining, our knowledge would be greatly impoverished. Over the past few years, we've been exploring underground coal mines in the United States, where entire forested landscapes have been preserved intact over huge areas. Never before have geologists had the opportunity to walk out through mile upon mile of fossilized forest. In this feature article, we describe some of our recent explorations and attempt to shed new light on these old fossils.  相似文献   

Dust supply from river floodplains: the case of the lower Huang He (Yellow River) recorded in a loess–palaeosol sequence from the Mangshan Plateau     

Maarten A. Prins  Hongbo Zheng  Kay Beets  Simon Troelstra  Patrick Bacon  Ilse Kamerling  Wouter Wester  Martin Konert  Xiangtong Huang  Wang Ke  Jef Vandenberghe 《第四纪科学杂志》2009,24(1):75-84

The Mangshan Plateau is located on the south bank of the Huang He (Yellow River) just west of the city of Zhengzhou, well outside the Loess Plateau in central China. Mixing models of the grain‐size data indicate that the loess deposits are mixtures of three loess components. Comparison of the mixing model with existing models established for a series of loess–palaeosol sequences from the Loess Plateau indicates that the Mangshan loess has been supplied from a proximal dust source, the Huang He floodplain, during major dust outbreaks. The high accumulation rates, the composition of the loess components, and especially the high proportions of a sandy loess component support this. Owing to the exceptionally high accumulation rates, the Mangshan grain size, magnetic susceptibility and carbonate records provide a high‐resolution archive of environmental and climate change. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Final report of IGCP Project 410 （1997-2002）——The Great Ordovician Biodiversification Event Department of Earth and Planetary Sciences, Macquarie University, North Ryde, NSW 2109, Australia. E-mail： bwebby@laurel.ocs.mq.edu.au     

BarryDWebby MaryL.Droser FlorentinParis 《《幕》》2004,27(3):203-208

In 1997, IGCP Project No. 410 was established to appraise known records of Ordovician biotas, in order to evaluate one of the greatest-ever diversifications of life on Earth, between 489 and 443 million years ago. Data collection and analysis of biodiversity were coordinated through seven regional teams, and a global“clade” team.  相似文献