A deep X-ray observation of M82 with XMM–Newton     

P. Ranalli †‡  A. Comastri  L. Origlia  R. Maiolino § 《Monthly notices of the Royal Astronomical Society》2008,386(3):1464-1480

We report on the analysis of a deep (100-ks) observation of the starburst galaxy M82 with the EPIC and RGS instruments onboard the X-ray telescope XMM–Newton . The broad-band (0.5–10 keV) emission is due to at least three spectral components: (i) continuum emission from point sources; (ii) thermal plasma emission from hot gas; and (iii) charge-exchange emission from neutral metals (Mg and Si). The plasma emission has a double-peaked differential emission measure, with the peaks at ∼0.5 and ∼7 keV. Spatially resolved spectroscopy has shown that the chemical absolute abundances are not uniformly distributed in the outflow, but are larger in the outskirts and smaller close to the galaxy centre. The abundance ratios also show spatial variations. The X-ray-derived oxygen abundance is lower than that measured in the atmospheres of red supergiant stars, leading to the hypothesis that a significant fraction of oxygen ions have already cooled off and no longer emit at energies ≳0.5 keV.  相似文献   

Spitzer observations of M33 and the hot star, H ii region connection     

Robert H. Rubin  Janet P. Simpson  Sean W. J. Colgan  Reginald J. Dufour  Gregory Brunner  Ian A. McNabb  Adalbert W. A. Pauldrach  Edwin F. Erickson  Michael R. Haas  Robert I. Citron 《Monthly notices of the Royal Astronomical Society》2008,387(1):45-62

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一种基于M估计的Robust-ELM滑坡位移预测方法     

高彩云  高宁 《大地测量与地球动力学》2019,39(2):153-157

采用传统ELM算法进行滑坡位移预测时，其网络输出权值由最小二乘估计得出，导致ELM抗差能力较差，从而造成网络训练参数不准确。为此，将M估计与ELM相结合，提出一种基于M估计的Robust-ELM滑坡变形预测方法。该方法利用加权最小二乘方法来取代最小二乘法计算ELM输出权值，以减少滑坡监测数据中粗差对ELM预测的干扰。分别以链子崖、古树屋滑坡体为例，将Robust-ELM进行了单维、多维粗差的抵御性验证。结果表明，该方法能够有效降低粗差对预测的影响，具有良好的抗差能力。  相似文献   

流动商贩的空间分布特征及与正规商业的分布关系——基于距离测度方法的数量研究   总被引：4，自引：1，他引：3  

张延吉  张磊  吴凌燕 《地理学报》2017,72(4):618-632

有关非正规经济的空间分布特征始终缺乏宏观维度的定量研究。本文利用数字化城市管理系统中的流动商贩数据和工商局登记的正规商业数据,通过DO指数和M函数,分别探究流动商贩的空间特征及其与正规商业的分布关系。研究发现：① 绝大多数类型的流动商贩及其占地面积具有显著集聚的空间格局;其中,与居民需求较为密切的商贩类型,集聚程度相对较低。② 相较于正规商业,流动商贩在极小的空间尺度上更为强烈地集聚分布;但随着尺度扩大,集聚程度呈快速衰减态势。③ 经营内容相近的流动商贩与正规商业之间表现出显著的互斥关系,而非共栖关系;且两者的互斥程度在较小的空间尺度上尤为强烈。由此,本研究证明设立摊贩疏导区具有可行性和必要性,并就设置的类型及原则提出了初步建议。  相似文献   

Excursion to Mid-lincolnshire,Easter, 1905: From April 20th to 26th, 1905     

Henry Preston 《Proceedings of the Geologists' Association. Geologists' Association》1905,19(3):114-IN4

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Excursion to Leicestershire: Whit-Monday,May 21st, 1877, and following day     

Wm. J. Harrison 《Proceedings of the Geologists' Association. Geologists' Association》1877,5(4):142-148

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Dehydration experiments on natural omphacites: qualitative and quantitative characterization by various spectroscopic methods   总被引：1，自引：0，他引：1  

M. Koch-Müller  I. Abs-Wurmbach  D. Rhede  V. Kahlenberg  S. Matsyuk 《Physics and Chemistry of Minerals》2007,34(9):663-678

A series of natural omphacites from a wide range of P, T occurrences were investigated by electron microprobe (EMP), infrared (IR)-, Mössbauer (MS)- and optical spectroscopy in the UV/VIS spectral range (UV/VIS), secondary ion mass spectrometry (SIMS) and single crystal structure refinement by X-ray diffraction (XRD) to study the influence of hydrogen loss on valence state and site occupancies of iron. In accordance with literature data we found Fe²⁺ at M1 as well as at M2, and in a first approach assigned Fe³⁺ to M1, as indicated by MS and XRD results. Hydrogen content of three of our omphacite samples were measured by SIMS. In combination with IR spectroscopy we determined an absorption coefficient: ε _i,tot = 65,000 ± 3,000 lmol_H2O ^?1 cm^?2. Using this new ε _i,tot value, we obtained water concentrations ranging from 60 to 700 ppm H₂O (by weight). Hydrogen loss was simulated by stepwise heating the most water rich samples in air up to 800°C. After heat treatment the samples were analyzed again by IR, MS, UV/VIS, and XRD. Depending on the type of the OH defect, the grade of dehydration with increasing temperature is significantly different. In samples relatively poor in Fe³⁺ (<0.1 Fe³⁺ pfu), hydrogen associated with vacancies at M2 (OH bands around 3,450 cm^?1) starts to leave the structure at about 550°C and is completely gone at 780°C. Hydrogen associated with Al³⁺ at the tetrahedral site (OH bands around 3,525 cm^?1, Koch-Müller et al., Am Mineral, 89:921–931, 2004) remains completely unaffected by heat treatment up to 700°C. But all hydrogen vanished at about 775°C. However, this is different for a more Fe³⁺-rich sample (0.2 Fe³⁺ pfu). Its IR spectrum is characterized by a very intense OH band at 3,515 cm^?1 plus shoulder at 3,450 cm^?1. We assign this intense high-energy band to vibrations of an OH dipole associated with Fe³⁺ at M1 and a vacancy either at M1 or M2. OH release during heating is positively correlated with decrease in Fe²⁺ and combined with increase in Fe³⁺. That dehydration is correlated with oxidation of Fe²⁺ is indirectly confirmed by annealing of one sample in a gas mixing furnace at 700°C under reducing conditions keeping almost constant OH^? content and giving no indication of Fe²⁺-oxidation. Obtained data indicate that in samples with a relatively high concentration of Fe²⁺ at M2 and low-water concentrations, i.e., at a ratio of Fe^{2+ M2}/H > 10 dehydration occurs by iron oxidation of Fe²⁺ exclusively at the M2 site following the reaction: \( {\left[ {{\text{Fe}}^{{{\text{2 + [ M2]}}}}{\text{OH}}^{ - } } \right]} = {\left[ {{\text{Fe}}^{{{\text{3 + [ M2]}}}} {\text{O}}^{{{\text{2}} - }} } \right]} + {\text{1/2}}\;{\text{H}}_{{\text{2}}} \uparrow . \) In samples having relatively low concentration of Fe²⁺ at M2 but high-water concentrations, i.e., ratio of Fe^{2+ M2}/H < 5.0 dehydration occurs through oxidation of Fe²⁺ at M1.  相似文献   

江苏常州4.2级地震前的重力变化     

宋浩  范文华  蒋成  王维  李婷婷  吴晓峰  代宪鹏 《大地测量与地球动力学》2022,42(12):1257-1261

利用江苏地区2019~2021年流动重力观测资料,分析江苏省常州市4.2级地震前不同时间尺度下的重力场变化。结果表明：1）0.5 a尺度重力场变化图像较好地反映了此次地震下降-转折上升-持续上升-反向变化及零值线附近发震的演化过程;2）常州4.2级地震前0.5 a和1 a尺度下的重力场均显示,地震发生在重力变化零值线附近。  相似文献   

礼县—罗家堡断裂晚第四纪活动特征:兼论1654年礼县8级地震孕震机制   总被引：5，自引：0，他引：5       下载免费PDF全文

杨晓平  冯希杰  黄雄南  宋方敏  李高阳  陈献程  张玲  黄伟亮 《地球物理学报》2015,58(2):504-519

1654年7月21日甘肃省礼县8级地震发生在南北地震带的中北段,该地区的构造变形和构造活动与青藏高原向北东方向的扩展密切相关,复杂的构造几何特征主要受控于东昆仑断裂、西秦岭北缘断裂和一系列北东向断裂.礼县—罗家堡断裂为一条北东东向的左旋走滑活动断裂,错断了含有仰韶文化红色陶瓷片的一级阶地堆积物,阶地面上断层陡坎高约1.5m.沿断裂带发现冲沟的左旋位错量为3~10m,晚更新世黄土中残留的断层陡坎高4.5~8m.其中两条冲沟中发现裂点,高3.5~3.9m,距断层陡坎的距离为16m.礼县—盐关—罗家堡—天水镇一带发育大量的滑坡,长轴走向与礼县—罗家堡断裂一致,滑坡体后缘、侧壁陡峭,出露晚第四纪黄土,鲜有植被覆盖.礼县—罗家堡断裂为1654年8级地震的发震断裂.综合分析认为,受青藏高原向北东方向的扩展,被西秦岭北缘断裂、礼县—罗家堡断裂和岷县—宕昌断裂围限的礼县次级地块向南东滑动可能导致了1654年礼县8级地震的发生.断裂北、南两侧地壳电性结构的差异为强震的孕育提供了深部构造条件.  相似文献   

基于强震和测震数据对鲁甸6.5级地震发震断层方向的研究     

冯蔚  刘杰  罗佳宏  侯建盛  徐婉桢 《地震地质》2015,37(1)

2014年8月3日16时30分,云南省昭通市鲁甸县发生M6.5地震,宏观震中位于鲁甸县龙头山镇(27.1°N,103.3°E),深度约12km。发震断层为NW向包谷垴-小河断裂,是NE向昭通-鲁甸断裂系的NW向次级走滑断层。文中利用鲁甸地震50个强震台站观测记录与135个测震台站观测记录,分别进行峰值加速度计算和S波辐射图案匹配,对此次地震发震断层方向进行讨论。结果表明,"NW向"的断层方向更符合强震、测震仪器观测值,同时与地震灾害现场调查结果一致。  相似文献