The University of Durham Mark 6 Gamma Ray Telescope     

P. Armstrong  P. M. Chadwick  P. J. Cottle  J. E. Dickinson  M. R. Dickinson  N. A. Dipper  S. E. Hilton  W. Hogg  J. Holder  T. R. Kendall  T. J. L. McComb  C. M. Moore  K. J. Orford  S. M. Rayner  I. D. Roberts  M. D. Roberts  M. Robertshaw  S. E. Shaw  K. Tindale  S. P. Tummey  K. E. Turver 《Experimental Astronomy》1999,9(2):51-80

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Measurement of sky clarity using MIR radiometers as an adjunct to atmospheric Čerenkov radiation measurements     

D. J. Buckley  M. C. Dorrington  P. J. Edwards  T. J. L. McComb  S. P. Tummey  K. E. Turver 《Experimental Astronomy》1999,9(4):237-249

A technique for detecting the presence of cloud in the field of view of an atmospheric erenkov telescope using a mid infra red radiometer is described. Models for the radiative emission from clear and cloudy skies are tested and found to represent the measurements.  相似文献   

Azimuthal seismic anisotropy in a zone of exhumed continental mantle, West Iberia margin     

P. B. Cole  T. A. Minshull  R. B. Whitmarsh 《Geophysical Journal International》2002,151(2):517-533

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双漏模式中的弥散宇宙γ射线     

周大庄 《中国天文和天体物理学报》1990,(2)

弥散宇宙γ射线产生于初级宇宙线的传播过程,本文利用宇宙线传播的“双漏模式”得出与实验观测谱接近的银河系弥散宇宙γ射线谱。  相似文献   

川东北通江-南江-巴中地区嘉陵江组二段白云岩储层预测研究     

季玉新  魏修成  刘春园  王棣 《地质学报》2008,82(3):353-359

南方海相碳酸盐岩的油气勘探潜力很大,白云岩是重要的碳酸盐岩储层类型,其储集空间类型复杂多样.通江-南江-巴中地区(简称通南巴地区)嘉二段白云岩以砂屑白云岩为主,发育多种溶孔、溶洞和多种裂缝,已钻井揭示了良好的油气前景,但因其时代较老、埋藏深、烃源岩差、保存条件差和储层条件差等,其储层预测和油气检测难度很大.本文以目标区三维地震资料为基础,在对储层的岩石物理、地质地震特征进行分析的基础上,利用应力应变分析、体相干、多方位地震裂缝预测、频率衰减梯度分析等技术对白云岩目标产气层进行了深入研究,预测出了目标层的裂缝发育区、孔洞发育区,并对流体分布情况进行了预测探讨.  相似文献   

Closed‐form aftershock reliability of damage‐cumulating elastic‐perfectly‐plastic systems          下载免费PDF全文

Iunio Iervolino  Massimiliano Giorgio  Eugenio Chioccarelli 《地震工程与结构动力学》2014,43(4):613-625

Major earthquakes (i.e., mainshocks) typically trigger a sequence of lower magnitude events clustered both in time and space. Recent advances of seismic hazard analysis stochastically model aftershock occurrence (given the main event) as a nonhomogeneous Poisson process with rate that decays in time as a negative power law. Risk management in the post‐event emergency phase has to deal with this short‐term seismicity. In fact, because the structural systems of interest might have suffered some damage in the mainshock, possibly worsened by damaging aftershocks, the failure risk may be large until the intensity of the sequence reduces or the structure is repaired. At the state‐of‐the‐art, the quantitative assessment of aftershock risk is aimed at building tagging, that is, to regulate occupancy. The study, on the basis of age‐dependent stochastic processes, derived closed‐form approximations for the aftershock reliability of simple nonevolutionary elastic‐perfectly‐plastic damage‐cumulating systems, conditional on different information about the structure. Results show that, in the case hypotheses apply, the developed models may represent a basis for handy tools enabling risk‐informed tagging by stakeholders and decision makers. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Using X‐ray observations to identify the particle acceleration mechanisms in VHE SNRs and “dark” VHE sources     

G. Pühlhofer 《Astronomische Nachrichten》2008,329(2):186-190

Very high energy (VHE) γ‐ray observations have proven to be very successful in localizing Galactic acceleration sites of VHE particles. Observations of shell‐type supernova remnants have confirmed that particles are accelerated to VHE energies in supernova blast waves; the interpretation of the γ‐ray data in terms of hadronic or leptonic particle components in these objects relies nevertheless strongly on input from X‐ray observations. The largest identified Galactic VHE source class consists of pulsar wind nebulae, as detected in X‐rays. Many of the remaining VHE sources remain however unidentified until now. With X‐ray observations of these enigmatic “dark” objects one hopes to solve the following questions: What is the astrophysical nature of these sources? Are they predominantly electron or hadron accelerators? And what is their contribution to the overall cosmic ray energy budget? The paper aims to provide an overview over the identification status of the Galactic VHE source population. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

GeV emission from neutron-rich internal shocks of some long γ-ray bursts     

Rong-Rong Xue  Yi-Zhong Fan  Da-Ming Wei 《Monthly notices of the Royal Astronomical Society》2008,389(1):321-324

In the neutron-rich internal shocks model for γ-ray bursts (GRBs), the Lorentz factors (LFs) of ion shells are variable, and so are the LFs of accompanying neutron shells. For slow neutron shells with a typical LF of approximate tens, the typical β-decay radius is  ∼10¹⁴–10¹⁵ cm  . As GRBs last long enough  [ T ₉₀ > 14(1 + z ) s]  , one earlier but slower ejected neutron shell will be swept successively by later ejected ion shells in the range  ∼10¹³–10¹⁵ cm  , where slow neutrons have decayed significantly. Part of the thermal energy released in the interaction will be given to the electrons. These accelerated electrons will mainly be cooled by the prompt soft γ-rays and give rise to GeV emission. This kind of GeV emission is particularly important for some very long GRBs and is detectable for the upcoming satellite Gamma-Ray Large Area Space Telescope (GLAST).  相似文献   

济阳坳陷罗家地区各向异性页岩储层全波场地震响应模拟及分析     

邓馨卉  刘财  郭智奇  刘喜武  刘宇巍 《吉林大学学报(地球科学版)》2018,48(4):1231-1243

济阳坳陷罗家地区页岩储层的固有各向异性及水平层理发育使得储层呈现VTI（vertical transversely isotropy）各向异性,而VTI各向异性背景下垂直裂缝的发育使得储层进一步呈现等效正交各向异性特征。本文以正交各向异性介质作为罗家页岩油储层模型,在岩石物理建模中应用Backus平均理论将测井尺度的VTI各向异性粗化至地震尺度,并利用Schoenberg理论在VTI各向异性背景中引入垂直裂缝,进而得到正交各向异性等效介质模型,同时考虑裂缝尺度和流体填充等因素。之后,应用各向异性反射率法进行全波场地震正演模拟,计算正交各向异性页岩油储层AVAZ（amplitude versus azimuth）响应,通过振幅的方位特征进行储层裂缝识别。计算结果表明,PP波、PSV波和PSH波方位振幅响应各不相同,且方位振幅分布图的拟合形状可反映裂缝的发育方向,为页岩油储层中裂缝的地震识别提供依据。  相似文献   

Crustal anisotropy of Taihang Mountain Range using azimuthal variation of receiver functions     

田宝峰  李娟  姚振兴 《地震学报(英文版)》2008,21(4):358-369

We discussed the possibility of studying crust anisotropy by analyzing azimuthal variation of the receiver functions and presented a technique for computing the transmission response of a flat-layered medium with arbitrarily ori-ented hexagonally symmetric anisotropy using the reflectivity algorithm. Using this method we investigated the crust anisotropy of Taihang Mountain Range (TMR). Our result shows that there is significant anisotropy with a slow symmetry axis in the upper crust and a fast symmetry axis in the lower crust. The anisotropy magnitude of about 8%~15% is found in the upper crust and a smaller magnitude of about 3%~5% in the lower crust. Orienta-tion of the symmetry axes and the depth of anisotropy appearance as deduced from the seismic records of four individual seismic stations are different from each other. The crust anisotropy beneath the four stations may be associated with the local crustal fabrics in a small area.  相似文献