Seismic reflection images of the Moho underlying melt sills at the East Pacific Rise

The determination of melt distribution in the crust and the nature of the crust-mantle boundary (the 'Moho') is fundamental to the understanding of crustal accretion processes at oceanic spreading centres. Upper-crustal magma chambers have been imaged beneath fast- and intermediate-spreading centres but it has been difficult to image structures beneath these magma sills. Using three-dimensional seismic reflection images, here we report the presence of Moho reflections beneath a crustal magma chamber at the 9 degrees 03' N overlapping spreading centre, East Pacific Rise. Our observations highlight the formation of the Moho at zero-aged crust. Over a distance of less than 7 km along the ridge crest, a rapid increase in two-way travel time of seismic waves between the magma chamber and Moho reflections is observed, which we suggest is due to a melt anomaly in the lower crust. The amplitude versus offset variation of reflections from the magma chamber shows a coincident region of higher melt fraction overlying this anomalous region, supporting the conclusion of additional melt at depth.     

Skew of mantle upwelling beneath the East Pacific Rise governs segmentation

Mantle upwelling is essential to the generation of new oceanic crust at mid-ocean ridges, and it is generally assumed that such upwelling is symmetric beneath active ridges. Here, however, we use seismic imaging to show that the isotropic and anisotropic structure of the mantle is rotated beneath the East Pacific Rise. The isotropic structure defines the pattern of magma delivery from the mantle to the crust. We find that the segmentation of the rise crest between transform faults correlates well with the distribution of mantle melt. The azimuth of seismic anisotropy constrains the direction of mantle flow, which is rotated nearly 10 degrees anticlockwise from the plate-spreading direction. The mismatch between the locus of mantle melt delivery and the morphologic ridge axis results in systematic differences between areas of on-axis and off-axis melt supply. We conclude that the skew of asthenospheric upwelling and transport governs segmentation of the East Pacific Rise and variations in the intensity of ridge crest processes.     

Foreshock sequences and short-term earthquake predictability on East Pacific Rise transform faults

East Pacific Rise transform faults are characterized by high slip rates (more than ten centimetres a year), predominantly aseismic slip and maximum earthquake magnitudes of about 6.5. Using recordings from a hydroacoustic array deployed by the National Oceanic and Atmospheric Administration, we show here that East Pacific Rise transform faults also have a low number of aftershocks and high foreshock rates compared to continental strike-slip faults. The high ratio of foreshocks to aftershocks implies that such transform-fault seismicity cannot be explained by seismic triggering models in which there is no fundamental distinction between foreshocks, mainshocks and aftershocks. The foreshock sequences on East Pacific Rise transform faults can be used to predict (retrospectively) earthquakes of magnitude 5.4 or greater, in narrow spatial and temporal windows and with a high probability gain. The predictability of such transform earthquakes is consistent with a model in which slow slip transients trigger earthquakes, enrich their low-frequency radiation and accommodate much of the aseismic plate motion.     

东亚经济崛起的文化诠释

东亚经济崛起引起了学界对马克斯.韦伯提出的关于儒家伦理不利于资本主义发展假说的质疑,也引起了对儒文化的反思和对东亚儒学文化圈价值的重估。儒文化于不同时代蕴育新内容的同时,也为文化诠释经济的理论发展提供了一个有效路径。在经济全球化发展趋势之下,把儒文化提升为更加适应东亚现代化发展的价值认同无疑成为儒文化走向的最终归宿。     

Rise and fall of political complexity in island South-East Asia and the Pacific

There is disagreement about whether human political evolution has proceeded through a sequence of incremental increases in complexity, or whether larger, non-sequential increases have occurred. The extent to which societies have decreased in complexity is also unclear. These debates have continued largely in the absence of rigorous, quantitative tests. We evaluated six competing models of political evolution in Austronesian-speaking societies using phylogenetic methods. Here we show that in the best-fitting model political complexity rises and falls in a sequence of small steps. This is closely followed by another model in which increases are sequential but decreases can be either sequential or in bigger drops. The results indicate that large, non-sequential jumps in political complexity have not occurred during the evolutionary history of these societies. This suggests that, despite the numerous contingent pathways of human history, there are regularities in cultural evolution that can be detected using computational phylogenetic methods.     

The finding of natural GaN crystals in sediments from the East Pacific Ocean

Although as one of the major constituents in pelagic sediments, clay minerals have not been used unambi guously to determine the origin, provenance, and envi ronments of deep sea sediments due to their poor crys tallization state, chemical complexity and …     

赤道东太平洋海表水温变化的多层次结构特征分析

以小波理论为基础来进行赤道东太平洋海表水湿变化的多层次结构特征分析,结果表明,赤道东太平洋海表水温的变化表现十分明显的多层次演变结构和突变特征,一级保留信息能较好反映从１９１年以来的历次厄尔尼诺事件和反厄尔尼诺事件,并对这些事件的强度,层次结构和突变等重要信息给予良好的表现,二,三级保留信息则分别反映了赤道东太平洋海温在另一层次里演变的结构特征,是对一级保留信息的增加和完善。     

大底盘双塔连体高层结构的地震响应分析

复杂高层建筑结构体系是随着经济增长而发展起来的一种结构体系,这种结构体系能满足较高的空间利用率,其中较为特殊的是一种底部带有大底盘、上部是塔楼的的结构形式。为了对此类结构形式进行更好的研究,对大底盘双塔结构和大底盘双塔连体高层的结构进行地震响应分析,利用有限元模型sap2000建立大底盘双塔结构模型和大底盘双塔连体结构模型,对上述模型分别进行模态分析和线性时程分析,得出二者之间的周期、质量参与系数和顶层位移的数据,进行对比分析。结果表明,在一定情况下,连接体对大底盘双塔高层结构有影响作用,对于高阶振型而言其平动和扭转的耦合作用有所加强,使扭转振型更加明显;用不同的地震波激励结构模型,对结构的极限状态也有影响;对于大底盘双塔连体结构,在一定条件下如何输入地震波对大底盘双塔连体结构的地震响应影响不大。     

基于K-medoids聚类分析的多相流相态辨识方法研究

为提高体积法测量多相流参数的准确性,提出了一种基于K-medoids聚类分析的多相流相态辨识方法研究.分析K-medoids算法,研究多相流相态特征,建立可除掉脏数据影响的K-medoids多相流相态识别模型,有效提高多相流各组分分相流量测量的准确性,并进行了实验验证.实验结果表明,该多相流相态识别模型能克服脏数据,有效提高多相流各组分分相流量测量的准确性,可提高多相流测量精度0.054 m3/d.采用该模型可准确识别多相流相态,提高多相流参数测量的准确性,从而为测井提供可靠的流速和相持率数据.     

The terraced thermal contrast among the Tibetan Plateau, the East Asian plain, and the western North Pacific and its impacts on the seasonal transition of East Asian climate

The heating sources over the Tibetan Plateau （TP）, the East Asian plain, and the western North Pacific （WNP） form a terraced thermal contrast in the west-east direction. Over East Asia and the WNP, this zonal thermal contrast contributes as high as 45 % to the seasonal variance based on the EOF analysis and exerts a significant impact on the seasonal transition of the East Asian climate through the enhancement of the year-round southerly to the southeast of the TP in late March and early April. This effect is investigated in this study using a high-resolution regional atmospheric model by doubling the surface sen- sible heat flux, respectively, over the TP, the East Asian plain, and the WNP in three sensitivity experiments. Comparisons among the experiments reveal that doubling the surface sensible heat flux over the WNP has little upstream response over East Asia. The increased zonal thermal contrast between the TP and the East Asian plain due to doubled heat flux over the TP would induce anomalous northerly over the region with year-round southerly to the southeast of the TP and weaken its seasonal enhancement. Doubling the surface sensible heat flux over the East Asian plain decreases the zonal thermal contrast and leads to southerly anomaly over the region with year-round southerly to the southeast of the TP and South China, which is favorable for the enhancement of the year-round southerly and its eastward extension.     

东太平洋结核区细菌调查及鉴定

对东太平洋结核区6个站点沉积物样品进行细菌培养和数量统计,发现各个站点间的细菌总量变化幅度较大,站点E2003-01的细菌量最多;细菌量纵向分布规律基本是从表层到深层逐渐递减.对所获得的菌株进一步用RFLP和16S rDNA 基因序列分析,发现所获得的菌株主要来自变形菌门(Proteobacteria)的α、β、γ亚群和放线菌门(Actinobacteria),厚壁菌门(Firmicutes) 等类群.此外还发现了与已知细菌菌种相似性在97%～95%之间的有12株,它们可能是新种;与已知细菌菌种相似性小于或等于95%的有4株,它们可能是新的属种.     

东太平洋结核区细菌调查及鉴定

对东太平洋结核区6个站点沉积物样品进行细菌培养和数量统计，发现各个站点间的细菌总量变化幅度较大，站点E2003-01的细菌量最多；细菌量纵向分布规律基本是从表层到深层逐渐递减．对所获得的菌株进一步用RFLP和16S rDNA基因序列分析，发现所获得的菌株主要来自变形菌门（Proteobacteria）的α、β、γ亚群和放线菌门（Actinobacteria），厚壁菌门（Firmicutes）等类群．此外还发现了与已知细菌菌种相似性在97％～95％之间的有12株，它们可能是新种；与已知细菌菌种相似性小于或等于95％的有4株，它们可能是新的属种．     

P2P流检测技术研究综述

P2P流量已经占据了整个网络流量的60%—70%,HTTP、EMAIL等传统的流量已经受到P2P流量的影响,同时伴随大量非授权内容的传播和安全问题。网络运营商、企业网和校园网为保证传统应用的性能,需要对P2P流量进行有效管理。要完成这一目标,首要工作是对P2P流的检测,把它和传统的流量区分出来。该文对P2P流检测主要方法进行了总结,将当前的检测方法分为基于报文层面、流层面和节点层面3大类,针对各类中具体的方法,分析了各自的优点和缺点,并进行了比较。提出将多种方法结合使用有效对P2P流进行检测。最后分析了P2P流检测技术进一步的研究方向。     

冬春海温异常对东亚初夏季风环流的影响

用ＯＳＵ的两层大气环流模式进行了热带西太平洋冬春海温异常对东亚初夏（５月）季风环流影响的数值试验．结果表明：①海温的负距平引起西太平洋副热带高压脊南落和西伸，东亚热带季风环流减弱，我国西南和华南地区的降水增加；②海温的正距平引起西太平洋副热带高压明显减弱，西太平洋的赤道西风加强，我国西南和华南地区的降水减少     

基于多特征的LS-SVM油水两相流流型识别

油水两相流的流型影响着流动参数的准确测量以及两相流系统的运行特性.针对电导波动信号的非平稳和非线性特点,采用统计理论、小波包理论和混沌理论相结合的方法对垂直上升管内油水两相流的电导波动信号进行分析,得到了11个反映油水两相流流动特性的特征参数,并将这些参数作为流型特征向量,运用最小二乘支持向量机进行训练并识别流型.实现了一种从不同类型、不同角度提取多个特征的流型识别算法,解决了现有算法中特征提取不足的问题.实验结果表明,这是一种有效的、高精度的识别方法.     

抗震概念设计在高设防烈度结构体系中的应用

＂5.12＂汶川特大地震的建筑震害调查表明,一栋抗震性能优良的建筑除了需进行必要的结构计算之外,更为重要的是概念设计.本文通过高设防烈度地区的高层建筑结构的工程实例,阐明了抗震概念设计的思想、方法及其在工程结构设计中的应用.     

汉冶萍公司兴衰之路的思考

汉冶萍公司是中国近代最早、最大的以股份制方式创建起来的钢铁煤联合企业,从创建至发展到消亡的58年历史进程中,不但为中国近代工业的发展做出了突出而重要的历史贡献,而且自身积淀着深厚的企业精神和企业文化。对当代中国工业发展有着独特的现实启示。     

简支钢桁梁桥作三维地震反应分析的支座地震力

探讨了将墩桁作为共同工作系统，进行铁路简支铜桁梁桥的三维地震反应分析来计算支座地震力的方法。分析了支座在地震时的受力机制．通过算例给出了支座的水平地震力和竖向地震力，并与传统的静力分析方法、单墩模型及单桁模型的计算作了比较。为钢桁梁桥支座的抗震设计提供了参考依据。     

Features of tropical cyclone landfalls over East Asia corresponding to three types of Pacific warming decaying phase

This study examines the tropical cyclone （TC） landfall activities over the East Asia in three types of decaying phase of warm sea surface temperature anomalies （SSTAs） over the equatorial central-eastern Pacific： eastern Pacific warming decaying to La Nifia, eastern Pacific warming decaying to a neutral E1 Nifio-Southern Oscilla- tion phase, and a central Pacific warming decaying year. Results show that, for the type of eastern Pacific wanning decaying to La Nifia, more TCs make landfall over Hainan Island and Beibu Gulf, whereas fewer TCs reach eastern China coast. In particular, the number of landfalling TCs remarkably decreases in the decaying phase of eastern Pacific E1 Nifio to a neutral year. During the decaying phase of central Pacific E1 Nifio events, more TCs tend to make landfall over southern China, Indochina Peninsula and the Philippines. The anomalies of atmospheric circu- lation and environmental conditions induced by the SSTAs over the tropical Pacific in the different decaying types are responsible for the evident variation in features of TC landfall.