Finding the most variable stars in the Orion Belt with the All Sky Automated Survey

We look for high‐amplitude variable young stars in the open clusters and associations of the Orion Belt. We use public data from the ASAS‐3 Photometric V ‐band Catalogue of the All Sky Automated Survey, infrared photometry from the 2MASS and IRAS catalogues, proper motions, and the Aladin sky atlas to obtain a list of the most variable stars in a survey area of side 5° centred on the bright star Alnilam (ε Ori) in the centre of the Orion Belt. We identify 32 highly variable stars, of which 16 had not been reported to vary before. They are mostly variable young stars and candidates (16) and background giants (8), but there are also field cataclysmic variables, contact binaries, and eclipsing binary candidates. Of the young stars, which typically are active Herbig Ae/Be and T Tauri stars with Hα emission and infrared flux excess, we discover four new variables and confirm the variability status of another two. Some of them belong to the well known σ Orionis cluster. Besides, six of the eight giants are new variables, and three are new periodic variables (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

基于多指标综合指数的灾害性天气过程预评估方案

通过分析给出了一种基于多指标综合指数的灾害性天气过程预评估方案,提出预估应包含对灾害性天气过程本身程度预估和灾害影响预估两个部分。通过建立综合指数来描述灾害性天气过程本身的程度,利用历史和实时气象资料对综合指数进行计算,分别对灾害性天气过程进行历史分析和实时监测;通过列表法,对收集的历史和实时灾害影响资料进行解析,综合指数中组合要素的差异,可用于分析灾害的不同特征;最后利用历史统计情景、相似指数年份类比和中短期预报等三种方案,对灾害性天气进程和影响发展程度进行预估。并以湖北省2008年初持续低温雨雪冰冻过程为例进行具体说明,此次过程综合指数值位居历史第二位,约70年一遇,直接经济损失超过110亿元,是1951年以来冬季损失最大的一次气象灾害。     

X‐rays from young stars: A summary of highlights from the XMM‐Newton Extended Survey of the Taurus Molecular Cloud (XEST)

The XMM‐Newton Extended Survey of the Taurus Molecular Cloud (XEST) is a survey of the nearest large star‐forming region, the Taurus Molecular Cloud (TMC), making use of all instruments on board the XMM‐Newton X‐ray observatory. The survey, presently still growing, has provided unprecedented spectroscopic results from nearly every observed T Tauri star, and from ≈50% of the studied brown dwarfs and protostars. The survey includes the first coherent statistical sample of high‐resolution spectra of T Tauri stars, and is accompanied by an U ‐band/ultraviolet imaging photometric survey of the TMC. XEST led to the discovery of new, systematic X‐ray features not possible before with smaller samples, in particular the X‐ray soft excess in classical T Tauri stars and the Two‐Absorber X‐ray (TAX) spectra of jet‐driving T Tauri stars. This paper summarizes highlights from XEST and reviews the key role of this large project. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

华南前汛期持续性暴雨年代际变化特征及成因

应用福建、广东、广西243个气象站1961-2012年逐日降水资料,构建华南前汛期暴雨强度指数,揭示了前汛期持续性暴雨年代际变化特征及其可能机理。研究表明:前汛期持续性暴雨经历了多发（1961-1972年）-少发（1973-1991年）-多发（1992-2012年）3个阶段,目前仍处于多发期,具有持续时间较长且强度增强的特点;由于前汛期降水的低频振荡受热带低频信号北传的调制,因此,导致这种显著年代际变化的可能成因是热带低频信号北传的周期和强度的年代际差异,当热带低频信号北传至华南时低频周期长（短）且强度强（弱）,则前汛期易出现持续时间长（短）且强度强（弱）的持续性暴雨。     

离子色谱分析中的样品预处理

总结了几种常用于离子色谱分析的样品预处理方法,其中包括流动相改性,气化分离法,离子交换法,膜技术,溶剂萃取,超临界流体萃取,固相萃取以及柱前和柱后衍生。引用主要参考文献１０篇。     

海洋沉积物中烃类化合物预处理条件优化及应用

运用分辨率高、稳定性好的ＨＰ６８９０ 毛细管气相色谱仪定性、定量测定海洋沉积物中的正构烷烃和多环芳烃。对沉积物样品的预处理中抽提、蒸发、柱层析、萃取等步骤条件进行优化。优化方法中,正构烷烃系列化合物回收率为６５ ％ ～７６ ％ ,多环芳烃系列化合物为８８ ％ ～９５％ ,标准偏差是２．７％ ～２０．２％ （ｎ＝ ３）     

X‐shooting Herbig Ae/Be stars: Accretion probed by near‐infrared He I emission

The Herbig Ae/Be stars are intermediate mass pre‐main sequence stars that bridge the gap between the low mass T Tauri stars and the Massive Young Stellar Objects. In this mass range, the acting star forming mechanism switches from magnetically controlled accretion to an as yet unknown mechanism, but which is likely to be direct disk accretion onto the star. We observed a large sample of Herbig Ae/Be stars with X‐shooter to address this issue from a multi‐wavelength perspective. It is the largest such study to date, not only because of the number of objects involved, but also because of the large wavelength coverage from the blue to the near‐infrared. This allows many accretion diagnostics to be studied simultaneously. By correlating the various properties with mass, temperature and age, we aim to determine where and whether the magnetically controlled mass accretion mechanism halts and the proposed direct disk accretion takes over. Here, we will give an overview of the background, present some observations and discuss our initial results. We will introduce a new accretion diagnostic for the research of Herbig Ae/Be stars, the HeI 1.083 μm line (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Multi‐slicing strategy for the three‐dimensional discontinuity layout optimization (3D DLO)

Discontinuity layout optimization (DLO) is a recently presented topology optimization method for determining the critical layout of discontinuities and the associated upper bound limit load for plane two‐dimensional and three‐dimensional (3D) problems. The modelling process (pre‐processing) for DLO includes defining the discontinuities inside a specified domain and building the target function and the global constraint matrix for the optimization solver, which has great influence on the the efficiency of the computation processes and the reliability of the final results. This paper focuses on efficient and reliable pre‐processing of the discontinuities within the 3D DLO and presents a multi‐slicing strategy, which naturally avoids the overlapping and crossing of different discontinuities. Furthermore, the formulation of the 3D discontinuity considering a shape of an arbitrary convex polygon is introduced, permitting the efficient assembly of the global constraint matrix. The proposed method eliminates unnecessary discontinuities in 3D DLO, making it possible to apply 3D DLO for solving large‐scale engineering problems such as those involving landslides. Numerical examples including a footing test, a 3D landslide and a punch indentation are considered, illustrating the effectiveness of the presented method. © 2016 The Authors. International Journal for Numerical and Analytical Methods in Geomechanics published by John Wiley & Sons Ltd.     

Evolution of Mount Fuji,Japan: Inference from drilling into the subaerial oldest volcano,pre‐Komitake

A buried, old volcanic body (pre‐Komitake Volcano) was discovered during drilling into the northeastern flank of Mount Fuji. The pre‐Komitake Volcano is characterized by hornblende‐bearing andesite and dacite, in contrast to the porphyritic basaltic rocks of Komitake Volcano and to the olivine‐bearing basaltic rocks of Fuji Volcano. K‐Ar age determinations and geological analysis of drilling cores suggest that the pre‐Komitake Volcano began with effusion of basaltic lava flows around 260 ka and ended with explosive eruptions of basaltic andesite and dacite magma around 160 ka. After deposition of a thin soil layer on the pre‐Komitake volcanic rocks, successive effusions of lava flows occurred at Komitake Volcano until 100 ka. Explosive eruptions of Fuji Volcano followed shortly after the activity of Komitake. The long‐term eruption rate of about 3 km³/ka or more for Fuji Volcano is much higher than that estimated for pre‐Komitake and Komitake. The chemical variation within Fuji Volcano, represented by an increase in incompatible elements at nearly constant SiO₂, differs from that within pre‐Komitake and other volcanoes in the northern Izu‐Bonin arc, where incompatible elements increase with increasing SiO₂. These changes in the volcanism in Mount Fuji may have occurred due to a change in regional tectonics around 150 ka, although this remains unproven.