节理面按产状的模糊聚类及其优势方位的确定

分析了已有的几种对节理面按产状分组方法的不足，指出应用模糊聚类对节理进行分组的原由。为了构造模糊矩阵，矩阵中的元素取为两节理面锐夹角的余弦，即两节理面向上的单位法向矢量点积的绝对值。对某组节理面向上的单位法向量进行部分反向后，其矢量之和对应的产状即为该组节理面的优势方位。     

施氮时期对‘马瑟兰’葡萄果实芳香物质组分与含量的影响

采用顶空固相微萃取技术（HS-SPME）、气相色谱-质谱联用技术（GC-MS）对‘马瑟兰’葡萄果实中芳香物质成分进行分析,分别在萌芽期、新梢旺长期、开花期、果实第1次膨大期、副梢旺长期和果实第二次膨大期一次性施入氮肥,以不施氮肥作为对照（CK）,研究不同施氮时期对果实芳香物质组分及含量的影响。结果表明：‘马瑟兰’葡萄果实中共检测出40种芳香物质成分,总含量为1 789.49—3 320.29 μg·kg^-1,其中有11种特征香气成分,以醇类和醛类化合物为主,氮素施用时期对果实芳香物质的成分和含量均有显著的影响;施氮可改变果实的香味特征,果实第二次膨大期施氮果实中芳香物质总含量最高且种类较多,有利于提高醇类、醛类及烷烃类化合物含量;该处理改变了果实以草香味为主的香味特征,此时花香和脂膏香最为浓郁;开花期施氮果实中草香、脂膏香和花香基本平衡,同时增加了果香味的比例。通过氮素施用时期可调控葡萄果实芳香物质的形成,进而改善果实的酿造品质。     

The Relationship between the Magnetic Cloud Boundary Layer and the Substorm Expansion Phase

The magnetic cloud boundary layer (BL) is a disturbance structure that is located between the magnetic cloud and the ambient solar wind. In this study, we statistically analyze the characteristics of the magnetic field B _z component (in GSM coordinates) inside the magnetic cloud boundary layers as well as the relationship between the magnetic cloud boundary layers and the magnetospheric substorms based on 35 typical BLs observed by Wind from 1995 to 2006. It is found that the magnetic field B _z components are more turbulent inside the BLs than those inside the adjacent sheath regions and the magnetic clouds. The substorm onsets are identified by the auroral breakups that are the most reliable substorm indicators by using the Polar UVI image data. The UVI data are available only for 17 BLs. The statistical analysis indicated that 9 of the 17 events triggered the substorms when BLs crossed the magnetosphere and that the southward field in the adjacent sheath region is a necessary condition for these triggering events. In addition, the SF-type BLs, which are named by their features of the B _z components inside the BLs and adjacent sheath regions, can easily trigger the substorms during their passage of the magnetosphere. SF-type BLs are characterized by sustained strong southward magnetic fields persisting for at least 30 minutes in the adjacent sheath regions and at least one change in the polarity of the B _z component inside the BL. In this study, 7 out of 8 such SF-type BL events triggered the substorm expansion phase, suggesting that the SF-type BLs are another important interplanetary disturbance source of substorms.     

Simulating spatiotemporal variability of blue and green water resources availability with uncertainty analysis

Due to rapid socioeconomic development, continuous population growth and urbanization, the world is facing a severe shortage of fresh water, particularly in arid and semi‐arid regions. A lack of water will put pressure on agricultural production, water pollution, as well as eco‐environmental degradation. Traditional water resources assessment mainly focused on blue water, ignoring green water. Therefore, analysis of spatiotemporal distribution of blue and green water resources in arid and semi‐arid regions is of great significance for water resources planning and management, especially for harmonizing agricultural water use and eco‐environmental water requirements. This study applied the Soil and Water Assessment Tool (SWAT) model and the Sequential Uncertainty Fitting algorithm (SUFI‐2) to calibrate and validate the SWAT model based on river discharges in the Wei River, the largest tributary of the Yellow River in China. Uncertainty analysis was also performed to quantify the blue and green water resources availability at different spatial scales. The results showed that most parts of the Wei River basin (WRB) experienced a decrease in blue water resources during the recent 50 years with a minimum value in the 1990s. The decrease is particularly significant in the most southern part of the WRB (the Guanzhong Plain), one of the most important grain production bases in China. Variations of green water flow and green water storage were relatively small both on spatial and temporal dimensions. This study provides strategic information for optimal utilization of water resources in arid and semi‐arid river basin. Copyright © 2014 John Wiley & Sons, Ltd.     

科尔沁沙地植物功能性状的尺度变异及关联

调查了科尔沁沙地流动沙丘、半固定沙丘和固定沙丘18个样地的物种组成,测定了28种植物的叶面积(LA)、比叶面积(SLA)和叶干物质含量(LDMC)等3个植物功能性状,并用性状梯度分析法对3个功能性状在群落水平上的变化进行了分解,研究了沙丘固定过程中的植物功能性状的尺度变异及其与生境变化的关系。结果表明:(1)随着沙丘的固定,群落平均LA逐渐增大,群落平均SLA及LDMC在半固定沙丘上最小;(2)群落平均SLA的生态位宽度随着沙丘固定程度依次减小,流动、半固定沙丘植物群落的适应能力较固定沙丘更强;(3)沙丘固定过程中物种性状值的变化与群落内共生植物种性状间变异的关联相比于群落间性状的变异更密切。沙丘固定导致了物种LA与LDMC较强的正相关关系,两性状在群落间的依赖性比群落内的强。物种在群落内和群落间采取不同的策略来适应沙丘固定过程生境的变化。     

电离层高频多普勒记录在扩展-F研究中的应用

本文通过观测实例探讨并论证了电离层高频多普勒观测在扩展-F研究中的应用.实例和相应分析表明:首先,由于高频多普勒记录的时间连续性,有利于从观测角度了解扩展-F的时间演化过程;其次,高频多普勒偏移对不规则结构造成的回波弥散、对不同尺度行进电离层扰动(TID)以及耀斑引起的突然频率偏移(SFD)效应都很敏感,这些现象在记录上出现的时间关系有利于了解扩展-F的触发因素或扩展-F与其他电离层背景扰动之间的联系或相互作用;最后,高频多普勒记录对于持续时间较长(几小时以上)或很短(小于1小时)的扩展-F都能够完整地反映,不会产生因为观测间歇形成的缺失,也可以有效区分究竟是连续一次还是一段时间内断续的扩展-F现象.高频多普勒观测有其自身的优点同时也具有一定的局限性,本文对其局限性诸如缺乏空间分辨率等也做了分析.指出发挥高频多普勒观测的优势,综合应用多种资料,通过不同手段的数据分析和比较,可以更好地为电离层扰动的物理机制和预报研究提供正确的观测依据.     

二维Vondrak滤波在高程异常拟合中的应用

将二维Vondrak滤波与多面函数拟合相结合应用到高程异常的拟合中,实例证明此方法在高程异常拟合中的应用是可行的,与单纯的多面函数拟合法相比,最大精度可提高76.4%,中误差降低54.72%。     

植硅体14C测年研究:过去、现在与未来

文章回顾了植硅体14C测年发展的历史,对当前其研究的现状进行了全面的总结和评述,对近年来其研究的争议进行了梳理。植硅体测年研究中存在的问题(如污染和老碳效应等)在其他材料测年过程同样存在,不能基于少量现代植物植硅体测年的异常数据而完全否定其意义。大量的测年数据显示,并不是所有的植硅体年代都偏老,相反地层中的植硅体年代与同层位其他材料的年代重合或接近。因此,在一些缺少其他有机质测年材料的地层,植硅体14C测年仍然是一种极具潜力的年代学方法,在构建一些重要环境和考古文化时间标尺上将会发挥更重要的作用。     

闽江下游白头山遗址稻旱混作农业的植硅体证据

稻作和旱作农业的起源与传播一直是植物考古和农业考古研究中的热点,闽江下游地区农业开始的时间及其发展过程对农业向南及向台湾传播的路径和时间研究至关重要,然而由于缺少详细的植物考古学工作,迄今为止关于该地区稻作和旱作农业开始的时间仍然是不清楚的。文章对闽江下游新发掘的闽侯县荆溪镇白头山遗址进行了系统的采样,通过考古学研究和14C测定确立了年代框架,对遗址进行了详细的植硅体分析。研究结果表明,白头山遗址主要包含闽江下游地区新石器时代晚期到末期的遗存(约5000~3000 cal.a B.P.),该遗址中植硅体类型丰富,自昙石山下层文化时期至黄瓜山文化时期,均发现有水稻特征型植硅体,黍子稃壳植硅体首次出现于昙石山文化层,说明在距今5000年左右稻作农业已经传播到了闽江下游,距今4700年左右的昙石山文化时期地层中黍子的出现则说明旱作农业的传入,形成了稻旱混作的原始农业格局。结合闽江流域及台湾地区其他的植物考古学工作,认为闽江是稻旱农业向台湾及东南亚地区传播的重要通道,研究结果为深入了解闽江流域新石器时代农业的发生、发展及其结构特征提供新的认识,为稻旱混作农业南传的时间及路径提供了新的证据。     

新马德里地震影响评估项目最新进展

畅销书Peaceof Mindin Earthquake Country最新版已完成创作并出版发行,新版内容更加丰富多彩。此书问世30年来为各地百姓在面对毁灭性地震时怎样保护亲人及家园的安全提供了很大帮助。