Time-resolved spectroscopy of the M15 X-ray binary AC211/X2127+119     

M. A. P. Torres  P. J. Callanan  M. R. Garcia 《Monthly notices of the Royal Astronomical Society》2003,341(4):1231-1238

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The origin of deep buried channels of Elsterian age in Northwest Germany     

Jürgen Ehlers  Gerhard Linke 《第四纪科学杂志》1989,4(3):255-265

Buried channels cut to a depth of over 100m into the underlying substratum of North Germany are almost exclusively of Elsterian age. Evaluation of geophysical well logs in the Hamburg area for the first time allows the construction of detailed longitudinal and transverse profiles. It can be shown that an apparently chaotic infill known from borehole records in some cases is actually a regular sedimentary sequence, fining from proximal to distal. Channel formation seems to have been the result of catastrophic meltwater release in the marginal parts of the ice sheet. The channel infill reflects these episodic outbursts of meltwater. During deglaciation, the channel remnants became infilled with fine sediments. The channels ceased to exist as morphologically detectable forms at the end of the Holsteinian Stage.  相似文献   

The P–T–X(fluid) evolution of meta‐anorthosites in the Eastern Granulites,Tanzania     

V. TENCZER  C. A. HAUZENBERGER  H. FRITZ  G. HOINKES  S. MUHONGO  U. KLÖTZLI 《Journal of Metamorphic Geology》2011,29(5):537-560

Meta‐anorthosite bodies are typical constituents of the Neoproterozoic Eastern Granulites in Tanzania. The mineral assemblage (and accessory components) is made up of clinopyroxene, garnet, amphibole; scapolite, epidote, biotite, rutile, titanite, ilmenite and quartz. Within the feldspar‐rich matrix (70–90% plagioclase), mafic domains with metamorphic corona textures were used for P–T calculations. Central parts of these textures constitute high‐Al clinopyroxene – which is a common magmatic mineral in anorthosites – and is therefore assumed to be a magmatic relict. The clinopyroxene rims have a diopsidic composition and are surrounded by a garnet corona. Locally the pyroxene is surrounded by amphibole and scapolite suggesting that a mixed CO₂–H₂O fluid was present during their formation. Thermobarometric calculations give the following conditions for the metamorphic peak of the individual meta‐anorthosite bodies: Mwega: 11–13 kbar, 850–900 °C; Pare Mountains: 12–14 kbar, 850–900 °C; Uluguru Mountains: 12–14 kbar, 850–900 °C. The P–T evolution of these bodies was modelled using pseudosections. The amount and composition of the metamorphic fluid and <0.5 mol.% fluid in the bulk composition is sufficient to produce fluid‐saturated assemblages at 10 kbar and 800 °C. Pseudosection analysis shows that the corona textures most likely formed under fluid undersaturated conditions or close to the boundary of fluid saturation. The stabilities of garnet and amphibole are dependent on the amount of fluid present during their formation. Mode isopleths of these minerals change their geometry drastically between fluid‐saturated and fluid‐undersaturated assemblages. The garnet coronae developed during isobaric cooling following the metamorphic peak. The cooling segment is followed by decompression as indicated by the growth of amphibole and plagioclase. The estimated of the metamorphic fluid is ～0.3–0.5. Although the meta‐anorthosites have different formation ages (Archean and Proterozoic) they experienced the same Pan‐African metamorphic overprint with a retrograde isobaric cooling path. Similar P–T evolutionary paths are known from the hosting granulites. The presented data are best explained by a tectonic model of hot fold nappes that brought the different aged anorthosites and surrounding rocks together in the deep crust followed by an isobaric cooling history.  相似文献   

基于X3D的虚拟场景设计方法     

杨帆  兰岚 《测绘工程》2013,22(4)

X3D是新一代国际标准的互联网3D图形软件规范、技术和产品,弥补2D平面世界很难满足人们需要的缺陷.文中应用3DSMax建模软件以及X3D三维图像标记语言,介绍一种虚拟三维场景设计方法.将三维场景的数据划分为建筑层、植被层、道路层和独立地物,利用X3D进行背景、灯光、视点等节点的设置以及用户交互方式,最终实现三维场景的建立与浏览,使浏览者身临其境地从各个角度进行全面观察.  相似文献   

基于GIS与X3D的井眼轨迹三维模拟应用     

郭延海  史云涛  高铁钢  熊亮  郑占国 《测绘与空间地理信息》2013,(Z1):179-181,185

分析了GIS和X3D相结合应用的技术特征,利用GIS与X3D开发了三维井斜图。以江苏油田某井为例,设计并实现了井眼轨迹的空间展示,提供井的设计与实钻轨迹、水平与垂直投影、靶区、邻井防碰等,实时掌握井轨迹信息,对于钻井作业具有重要的意义。  相似文献   

Visualization and level-of-detail of metadata for interactive exploration of Sensor Web     

《International Journal of Digital Earth》2013,6(11):847-869

There are several issues with Web-based search interfaces on a Sensor Web data infrastructure. It can be difficult to (1) find the proper keywords for the formulation of queries and (2) explore the information if the user does not have previous knowledge about the particular sensor systems providing the information. We investigate how the visualization of sensor resources on a 3D Web-based Digital Earth globe organized by level-of-detail (LOD) can enhance search and exploration of information by easing the formulation of geospatial queries against the metadata of sensor systems. Our case study provides an approach inspired by geographical mashups in which freely available functionality and data are flexibly combined. We use PostgreSQL, PostGIS, PHP, and X3D-Earth technologies to allow the Web3D standard and its geospatial component to be used for visual exploration and LOD control of a dynamic scene. Our goal is to facilitate the dynamic exploration of the Sensor Web and to allow the user to seamlessly focus in on a particular sensor system from a set of registered sensor networks deployed across the globe. We present a prototype metadata exploration system featuring LOD for a multiscaled Sensor Web as a Digital Earth application.  相似文献   

A component approach for the hysteretic behaviour of connections in cross‐laminated wooden structures     

Giovanni Rinaldin  Claudio Amadio  Massimo Fragiacomo 《地震工程与结构动力学》2013,42(13):2023-2042

In this paper, a numerical model to estimate the dissipative capacity and describe the cyclic response of cross‐laminated (X‐lam) timber buildings is presented. The connections between panels and to the foundation (metal hold‐downs and angle brackets, and screwed connectors) are modelled with nonlinear hysteretic multispring elements taking into account the strength interaction between different degrees of freedom according to a predefined domain. The timber components (solid X‐lam floors and wall panels) are modelled using elastic shell elements. By calibration on experimental cyclic tests carried out on each degree of freedom, important features of timber connection behaviour such as post‐peak strength, pinching and stiffness degradation can all be considered. In addition, the effect of friction at the interface between panels and with foundation can be taken into account. These springs have been implemented as external subroutines in a widespread software package such as Abaqus. By comparison with the experimental results of cyclic tests carried out on single X‐lam walls, coupled X‐lam walls and a single‐storey X‐lam building, the accuracy of the proposed model is demonstrated. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Space astronomy for the mid‐21st century: Robotically maintained space telescopes     

N. Schartel 《Astronomische Nachrichten》2012,333(3):209-212

The historical development of ground based astronomical telescopes leads us to expect that space‐based astronomical telescopes will need tobe operational for many decades. The exchange of scientific instruments in space will be a prerequisite for the long lasting scientific success of such missions. Operationally, the possibility to repair or replace key spacecraft components in space will be mandatory. We argue that these requirements can be fulfilled with robotic missions and see the development of the required engineering as the main challenge. Ground based operations, scientifically and technically, will require a low operational budget of the running costs. These can be achieved through enhanced autonomy of the spacecraft and mission independent concepts for the support of the software. This concept can be applied to areas where the mirror capabilities do not constrain the lifetime of the mission (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Solar wind charge exchange and local hot bubble X‐ray emission with the DXL sounding rocket experiment     

M. Galeazzi  M.R. Collier  T. Cravens  D. Koutroumpa  K.D. Kuntz  S. Lepri  D. McCammon  F. S. Porter  K. Prasai  I. Robertson  S. Snowden  N.E. Thomas  Y. Uprety 《Astronomische Nachrichten》2012,333(4):383-387

The Diffuse X‐ray emission from the Local Galaxy (DXL) sounding rocket is a NASA approved mission with a scheduled first launch in December 2012. Its goal is to identify and separate the X‐ray emission of the solar wind charge exchange (SWCX) from that of the local hot bubble (LHB) to improve our understanding of both. To separate the SWCX contribution from the LHB, DXL will use the SWCX signature due to the helium focusing cone at l = 185°, b = –18°. DXL uses large area proportional counters, with an area of 1000 cm² and grasp of about 10 cm² sr both in the 1/4 and 3/4 keV bands. Thanks to the large grasp, DXL will achieve in a 5‐minute flight what cannot be achieved by current and future X‐ray satellites (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Ion‐ion charge exchange and X‐rays from the winds of hot stars     

A.M.T. Pollock 《Astronomische Nachrichten》2012,333(4):351-354

Charge exchange occurs between charged ions with enough energy to overcome Coulomb repulsion, a condition satisfied for collisions at velocities like those of the winds driven from hot stars by radiation pressure. X‐ray line ratios in some hot stars are inconsistent with those expected from thermal plasmas excited by electron impact. Ion‐ion interactions including charge exchange might be responsible instead if high‐velocity collisions between ions are enabled by the presence of a magnetic field in the wind, suggesting a possible alternative mechanism to the widely accepted instability‐driven shock model. The nature of a plasma in charge‐exchange equilibrium is yet to be determined (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献