Chandra and RXTE spectroscopy of the Galactic microquasar XTE J1550−564 in outburst     

J. M. Miller  H. L. Marshall  R. Wijnands †  T. Di Matteo  D. W. Fox  J. Kommers  D. Pooley  T. Belloni  J. Casares  P. A. Charles  A. C. Fabian  M. van der Klis  W. H. G. Lewin 《Monthly notices of the Royal Astronomical Society》2003,338(1):7-13

  相似文献   

Hard X-ray spectrum of Mkn 421 during the active phase     

R. K. Manchanda 《Journal of Astrophysics and Astronomy》2001,22(2-3):145-154

Spectral measurement of Mkn 421 were made in the hard X-ray energy band of 20–200 keV using a high sensitivity, large area scintillation counter telescope on November 21, 2000 and these coincided with the onset of an active X-ray phase as seen in the ASM counting rates on board RXTE. The observed spectrum can not be fitted to a single power law similar to the PDS data of BeppoSAX. The data can be fitted both by a two component power-law function or a combination of an exponential function with a power law component at the high energies above 80 keV. We identify these components with those arising from the synchrotron self compton and the high energy power-law tail arising from the upgrading of the thermal photons due to multiple Compton scattering a la Cyg X-1. A comparison with the earlier data clearly suggests a spectral variability in the hard X-ray spectrum of the source. We propose a continuously flaring geometry for the source as the underlying mechanism for energy release.  相似文献   

介质横向不均匀对震后地表位移场的影响     

朱桂芝  王庆良  李辉  唐文 《大地测量与地球动力学》2003,23(4):54-59

利用三维有限元模拟两层地球模型(包括弹性层和粘弹性层)介质的横向不均匀和断层错动的复杂性对震后地表位移场的影响，其数值结果包括弹性解和粘弹性解。结果表明，震后位移场的分布特征不仅与粘弹性层的流变特性有关，还与弹性层介质的剪切模量以及断层的同震错动有关。  相似文献   

Uses and limitations of relativistic jet proper motions: lessons from Galactic microquasars     

R. P. Fender 《Monthly notices of the Royal Astronomical Society》2003,340(4):1353-1358

  相似文献   

Deep Processes of Basin Evolution:A Case Study of the Southern Songliao Basin and Adjacent Area,NE China in Mesozoic-Cenozoic     

Rihui Cheng  Dongpo Wang  Linfu Xue 《东北亚地学研究》2003,(1)

1IntroductionOne of the key factors related to basin geody-namics is deep process controlling formation and evolution of sedimentary basin. Depth and tempera-ture of asthenosphere,existence of mantle plume,occurrence of mantle melting,and amounts of melts under depressurization during thinning of lithosphere are controlling factors influenced formation and characteristics of extensional basin directly (Li,1994). Rifting is probably governed by frictional forces exerted on the base of litho…  相似文献   

Tests and constraints on theories of galaxy formation and evolution     

Rodger I. Thompson 《Astrophysics and Space Science》2003,284(2):353-356

Tests and constraints on current theories of galaxy formation and evolution are presented. They are derived from observations of the Northern Hubble Deep Field with WFPC2 and NICMOS. Photometric redshifts, extinctions and spectral energy distributions are calculated for all objects in the field. The tests and constraints are derived from the output of this analysis. The tests of the predictions from hierarchical and pure luminosity evolution galaxy evolution calculations favor the hierarchical model. Constraints are provided by the current luminosity function and its evolution to a redshift of 6. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Constraints on the ultraviolet metagalactic emissivity using the Lyα forest     

Avery Meiksin  Martin White 《Monthly notices of the Royal Astronomical Society》2003,342(4):1205-1214

  相似文献   

Reliability assessment of serviceability performance of braced retaining walls using a neural network approach     

A. T. C. Goh  F. H. Kulhawy 《国际地质力学数值与分析法杂志》2005,29(6):627-642

In urban environments, one major concern with deep excavations in soft clay is the potentially large ground deformations in and around the excavation. Excessive movements can damage adjacent buildings and utilities. There are many uncertainties associated with the calculation of the ultimate or serviceability performance of a braced excavation system. These include the variabilities of the loadings, geotechnical soil properties, and engineering and geometrical properties of the wall. A risk‐based approach to serviceability performance failure is necessary to incorporate systematically the uncertainties associated with the various design parameters. This paper demonstrates the use of an integrated neural network–reliability method to assess the risk of serviceability failure through the calculation of the reliability index. By first performing a series of parametric studies using the finite element method and then approximating the non‐linear limit state surface (the boundary separating the safe and ‘failure’ domains) through a neural network model, the reliability index can be determined with the aid of a spreadsheet. Two illustrative examples are presented to show how the serviceability performance for braced excavation problems can be assessed using the reliability index. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Entropy of the intracluster medium at high redshift     

Biman B. Nath 《Monthly notices of the Royal Astronomical Society》2004,353(3):941-946

  相似文献   

Historical space as narrative medium: on the configuration of spatial narratives of time at historical sites   总被引：1，自引：0，他引：1  

Maoz Azaryahu  Kenneth E. Foote 《GeoJournal》2008,73(3):179-194

This paper examines how narratives of history are organized spatially at historical sites and memorial spaces, especially in urban settings and in places invested with a sense of collective memory. Much recent research has focused on landscape, memory, and place and how relationships of political and social power influence the representation of historical events in public spaces. Although the meaning of such sites may be hotly contested for long periods of time, we focus here on narrative theory and the related, but unexplored, issue of how such historical stories are configured on the ground at actual historical sites. We identify a number of narrative strategies which are frequently used to configure historical stories in space. Declamatory strategies using markers presenting a snapshot of an event are common, but sequential and non-sequential linear strategies are also used, as are thematic strategies that cross-cut space and time to present complex historical stories at various spatial scales. Examples are drawn from a range of historical sites in North America, Europe and Israel.  相似文献