长江口斜压诊断模式三维流场数值模拟   总被引：4，自引：0，他引：4       下载免费PDF全文

龚政  张长宽  金勇  张东生 《水科学进展》2004,15(3):300-306

建立了σ坐标系下长江口斜压诊断模式三维流场数学模型,采用k-kl二方程紊流闭合模型求解垂向涡粘系数,计算域内恒定、非均匀盐度场反映了计算域密度斜压效应。验证结果表明,斜压诊断模式的模拟成果较切合实际。模型成功复演了长江口水域由往复流向旋转流过渡的流场特性;潮波从四条汊道传入后在分汊口附近相遇形成多个会潮点,其位置随着径流的大小、潮汐的强弱、汊道的形态等因素而变化。  相似文献   

Caractéristiques et signification d'un niveau coquillier majeur à brachiopodes,marqueur événementiel dans l'évolution dévonienne de la Saoura (Sahara du Nord-Ouest,Algérie)     

Abdelkader Ouali Mehadji  Serge Elmi  Patrick Rachebœuf  Larbi Mekahli 《Comptes Rendus Geoscience》2004,336(14):1283-1292

In the Saoura, the brachiopod shell beds, so-called niveau coralligène, correspond to a major shell deposit dated to the Late Emsian. Brachiopods and crinoids dominate the benthic assemblage that contains also corals, bryozoans, trilobites, goniatites, and orthocones. This major level has a large geographic distribution and it is characterized by a wide brachiopod diversity due to time-averaging, taphonomic feedback and alternate bottom conditions changing from soft to shelly and firm. This kind of brachiopod association is linked to a transgressive onlap system. At regional extent, we can correlate this major shell bed to similar shell deposits from the Ahnet-Mouydir, Tindouf, and Zemmour areas. It indicates an important transgressive event underlined by change in the sedimentation from detritic deposits to carbonate sediments. To cite this article: A. Ouali Mehadji et al., C. R. Geoscience 336 (2004).  相似文献   

Coastline configuration and geomorphologic development mode of arc-shaped coast in South China   总被引：1，自引：0，他引：1  

Dai Zhijun  Li Chunchu 《地理学报(英文版)》2004,14(4):473-480

1IntroductionArc-shaped bays are quite common on exposed sediment coast in South China, where the crenulate-bay beaches occur with the presence of two consecutive headlands and a predominant wave approach oblique to the alignment of the upcoast and downcoast headlands (Yasso, 1965). Oblique persistent swell striking a shoreline transports sediment alongshore and sculptures a coast into arc-shaped beaches. The shoreline of beach appearance mainly consists of straight segment and shadow segment…  相似文献   

基于GIS的油气储层综合评价方法研究   总被引：5，自引：0，他引：5  

施冬  陈军  朱庆 《武汉大学学报(信息科学版)》2004,29(7):592-596

通过对现有的商用地理信息系统的分析，剖析了传统的储层综合评价方法及存在的问题。充分利用GIS工具，建立油气储层评价空间数据库，整合各种与储层相关的多学科油田图形信息及其相关属性信息，利用GIS与储层评价模型集成解决油气储层评价问题，扩展了GIS的空间分析功能，实现了油气储层评价的科学性和完备性，并以西部某油田为例进行了实例分析。  相似文献   

Iteration method to determine the eigenvalues and eigenvectors of a target multiplet including full mode coupling   总被引：2，自引：0，他引：2  

Arwen Deuss  John Woodhouse 《Geophysical Journal International》2004,159(1):326-332

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Temporal Characteristics of Pacific Decadal Oscillation (PDO) and ENSO and Their Relationship Analyzed with Method of Empirical Mode Decomposition (EMD)   总被引：3，自引：1，他引：3  

HE Juanxiong  YU Zhihao  YANG Xiuqun 《Acta Meteorologica Sinica》2005,19(1):83-92

1. IntroductionPacific Decadal Oscillation (PDO) is a long-termENSO-like variability of the North Pacific. It can becharacterized by the first principal component of EOFof the North Pacific SST (Zhu and Yang, 2003; Tren-berth, 1990; Yang and Zhang, 2003). ENSO is thestrongest signal of annular change of global climatesystem (Trenberth, 1997). The spatial pattern of PDOis a wedge similar to El Nino. In the cool (warm)phases of PDO, the central and northwest Pacific is ofwarm (co…  相似文献   

Partial melting controls on the northwest Kyushu basalts from Saga-Futagoyama     

Hidehisa  Mashima 《Island Arc》2005,14(2):165-177

Abstract   The major element and compatible trace element compositions of the northwest Kyushu basalts (NWKBs) collected from Saga-Futagoyama were analyzed to examine the petrogenesis of these basalts. Although nepheline-normative alkaline basalts are not found in the basalts from Saga-Futagoyama, the Saga-Futagoyama basalts almost cover the major element variations of NWKBs. The basalts can be chemically divided into two groups: an Fe-poor group (IPG) and an Fe-rich group (IRG). The compositional variation of IPG basalts is essentially controlled by the partial melting of the source as suggested by the following: (i) bulk rock MgO, FeO and NiO compositions indicate that some IPG samples were equilibrated with mantle olivine; and (ii) correlations between Al₂O₃, CaO and MgO are consistent with those of experimental partial melts of peridotites. The inconsistent behaviors of the elements compatible with clinopyroxene (Cpx), such as V (Sc and Cu), preclude the significant role of the fractional crystallization of Cpx and spinel in IPG variation. IPG basalts have low Al and high Fe concentrations compared to the products of melting experiments involving peridotites and pyroxenites, suggesting that the IPG source would have a lithology and bulk rock composition different from those of typical peridotites and pyroxenites. IRG basalts have negative correlations between Fe₂O₃* and MgO, and between V and Fe₂O₃*/MgO, indicating that IRG basalts would have fractionated Cpx. However, the anomalously Fe-rich feature of IRG basalts compared with NWKBs collected from other areas suggests that the role of Cpx fractionation in NWKBs is minor. Relatively low melting temperatures would have principally caused the large chemical variation of NWKBs.  相似文献   

Hydrogeochemistry of karst underground waters at shallow depth in Guiyang City, Guizhou Province     

董志芬  朱立军吴攀沈峥  封志勇 《中国地球化学学报》2005,24(2):194-200

The aim of this study is to shed light on the hydrogeochemical characteristics of karst underground waters at shallow depth in Guiyang City, Guizhou Province with an emphasis on the geochemistry of major elements. Guiyang City bears abundant underground waters and it is also an important representative of the karst areas throughout the world. Ca^2 and Mg^2 are the dominant cations, accounting for 81% -99.7% of the total, and HCO3^- and SO4^2- are the dominant anions. Weathering of limestones and dolostones is the most important factor controlling the hydrogeochemistry of underground waters, and weathering of sulfate and evaporite rocks is less important. Moreover, the precipitation and human activities also have a definite influence on the hydrogeoehemistry of underground waters in the region studied.  相似文献   

An attempt to estimate isotropic and anisotropic lateral structure of the Earth by spectral inversion incorporating mixed coupling   总被引：2，自引：0，他引：2  

Hitoshi Oda 《Geophysical Journal International》2005,160(2):667-682

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泥石流运动衰减动力学初步研究     

陈洪凯唐红梅  吴四飞 《中国地质灾害与防治学报》2005,16(B12):56-61

我国公路泥石流病害严重，泥石流淤埋公路构建筑物是一类常见的公路泥石流病害类型。泥石流衰减动力学是防治泥石流淤埋病害的重要关键技术，也是泥石流运动学、动力学研究的核心问题之一。本文作者运用泥沙运动力学及流体力学原理，初步建立了泥石流固相颗粒和液相浆体的能量衰减条件，把泥石流衰减模式概化为两类，即能量抑制衰减和能量自由衰减；通过泥石流沉积模型试验，得到了不同粘度泥石流体的沉积扇变化形态，随着泥石流体粘度的增大，沉积扇边缘变陡、扩展范围变小、纵轴线长度减小等结论与实际情况吻合；初步建立了泥石流能量衰减速率计算方法。研究成果为防治公路泥石流病害奠定了基础。  相似文献