Fe-Al-Mg-MMH/溪膨润土分散体系触变性研究     

刘崇宇  陈泉水  郑举功  任广元 《华东地质学院学报》2009,32(2):167-171

研究了Fe-Al-Mg-混合金属氧化物（简称MMH）／金溪膨润土（简称MT）分散体系的触变性。实验表明,在不同的MMH／MT质量比（R）条件下,分散体系可分别呈现正触变性和负触变性。考察了pH值对纯金溪膨润土和Fe-Al-Mg-MMH／金溪膨润土分散体系触变性的影响。发现pH值能影响体系的触变性类型。当R值较小时（0～0．051）,随着pH值增加,体系的触变性发生负触变性-复合触变性-正触变性的转化;而R较大的体系（0．091）,在所研究的pH范围内（7．28～12．00）,随着pH值增加,体系由复合触变性向负触变性转化。并对影响机理进行了初步探讨。  相似文献   

The role of magnetostatic interactions in sediment suspensions     

D. Heslop  A. Witt  T. Kleiner  K. Fabian 《Geophysical Journal International》2006,165(3):775-785

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广义混合律及其在地球材料流变学中的应用   总被引：2，自引：0，他引：2  

嵇少丞  王茜夏斌许志琴 《岩石学报》2006,22(7):2067-2080

本文总结了广义混合律的基本特征，并以具弱相支撑结构的固液相悬浮液（岩浆）和具强相支撑结构的多孔材料（玄武岩、砂岩或部分熔融岩石）为例，系统地介绍了广义混合律在预测多矿物岩石或复合材料弹性力学或流变学性质随组分性质、体积分数和显微构造而变化的应用。广义混合律与现存理论的紧密吻合以及对多矿物岩石和复合材料力学性质描述的准确性绝非偶然，隐藏其后必有尚未人知的物理基础。严格的理论证明极可能是数学力学上富于挑战性的课题。  相似文献   

自锚式悬索桥主桥动力特性分析   总被引：5，自引：1，他引：5  

赵卓  张哲  刘东旭 《世界地震工程》2006,22(3):84-88

以某自锚式悬索桥主桥为研究对象,采用M IDAS有限元程序,建立了该桥的空间力学计算模型,利用子空间迭代法计算了该桥梁结构的自振频率和振型,结合计算结果对桥梁的动力特性和刚度特点进行了讨论。计算结果可为该类型桥梁的设计、施工以及使用阶段的健康检测和维护提供技术参数和依据。  相似文献   

Study of the elemental composition of suspended particles in large northern-Asian lakes （Baikal and Khubsugul）     

Vladimir Potemkin Tatjana Potemkina 《中国地球化学学报》2006,25(B08):135-136

Lakes Baikal （Russia） and Khubsugul （Mongolia） are rift freshwater water bodies. The maximal depth of Baikal is 1642 m, that of Khubsugul -238 m. One of the important aspects in the study of suspended matter is its geochemical composition which depends on mineralogy and granulometry of the suspended matter. As the concentration of suspended matter in the sites of deep lakes is not high - about 1 mg/L, to determine the elements in the suspended matter the monochromatized synchrotron radiation method （SRXFA, Novosibirsk, Russia） was used. Water sampling was conducted in three basins of Lake Baikal and in Lake Khubsugul on central vertical cross-sections and in near-coastal sites. The water samples were collected with 10-liter batometers. The suspension was extracted from the water by filtration under vacuum through ＂Nuclepore＂ filters of 47 mm in diameter with pore size of 0.4 mkm. The mean weight of dry suspension on the filters was about 1 rag. The results of study of lacustrine suspended matter show that such elements as Fe, Ca, Mn, Ti, V, Cr, Cu, Zn, Pb dominate in lakes Baikal and Khubsugul. The concentration of other elements is low. On the whole, the vertical distribution of total amount of suspended matter in open Baikal decreases from the surface to the bottom. As for Lake Khubsugul, it increases.  相似文献   

测算地球位数及点位高程的新方法     

贾剑钢  范东明黄丁 《四川测绘》2005,28(2):53-55

高程是地理空间数据中必需的数据元素。本文提出了一种直接测算两点间重力位能差，即地球位数，以求算高程的新方法，在理论上阐述了该方法的正确性和有效性，并对其应用前景进行了初步分析。  相似文献   

Estimates of present-day erosion based on sediment transport in rivers: a case study in Taiwan     

Fung-Chun Li  Jacques Angelier  Rou-Fei Chen  Hui-Ming Hsieh  Benoît Deffontaines  Ching-Ruey Luo  Tso-Tchang Wu  Ming-Chao Lin 《Comptes Rendus Geoscience》2005,337(13):1131-1139

We discuss the present-day sediment transport by rivers, and hence the erosion rate in upstream basins, based on the example of Taiwan Rivers where large datasets are available. After data correction, the values of the suspended sediment load in the lower Kaoping River are nearly three times smaller than those from the literature. On the other hand, we add the bed load evaluated from numerical modelling, despite limitations from data and models. Whereas the contribution of the chemical denudation rate in Taiwan is minor, the bed load is significant and must be evaluated. We point out that biases in data collection may favour high values of suspended load data, and that large series of datasets are needed to reduce uncertainties and smooth the time variability effect. To cite this article: F.-C. Li et al., C. R. Geoscience 337 (2005).  相似文献   

Sediment suspension dynamics and a new criterion for the maintenance of turbulent suspensions     

MIKE R. LEEDER  THOMAS E. GRAY  JAN ALEXANDER 《Sedimentology》2005,52(4):683-691

The vertical component of the turbulent flow acceleration term, , is used to determine the net positive vertical force that may support a suspended sediment load. A dimensionless criterion, Λ, is proposed for the maintenance of suspension, defined as the ratio of the maximum vertical turbulent stress to immersed weight of the suspended load above a unit bed area. In order that a suspension be maintained: where v ′ is instantaneous vertical turbulent velocity, σ and ρ are solid and fluid densities, respectively and m is the suspended load dry mass. The Λ criterion is dynamic, being a ratio of stresses and is analogous in this respect to Shields dimensionless stress criterion, θ, for the initiation of bedload motion. The new criterion is successful in predicting the maintenance of steady-state suspended sediment transport in open channel shear flow and deposition from non-uniform particulate density flows of wall jet type.  相似文献   

Steady-state vertical distribution of cohesive sediments in a flow   总被引：1，自引：0，他引：1  

Martin Sánchez  Patricia Grimigni  Yann Delanoë 《Comptes Rendus Geoscience》2005,337(3):357-365

Settling velocity of diluted suspended aggregates is examined under steady-state conditions. It is shown that if the local settling velocity of the suspended mass of sediments at the bottom is gamma distributed, then, the vertical variation of the local mean settling velocity $\overline{W}$ is proportional to a power $1/r$ of the local concentration C, where r is the gamma distribution parameter. That is a consequence of the suspended-sediment sorting produced by the vertical dynamics. The parameter r characterizes the range of settling velocity values for all the aggregates simultaneously in suspension. To cite this article: M. Sánchez et al., C. R. Geoscience 337 (2005).  相似文献   

Regional controls on geomorphology, hydrology, and ecosystem integrity in the Orinoco Delta, Venezuela     

Andrew G. Warne  Robert H. Meade  William A. White  Edgar H. Guevara  James Gibeaut  Rebecca C. Smyth  Andres Aslan  Thomas Tremblay 《Geomorphology》2002,44(3-4)

Interacting river discharge, tidal oscillation, and tropical rainfall across the 22,000 km² Orinoco delta plain support diverse fresh and brackish water ecosystems. To develop environmental baseline information for this largely unpopulated region, we evaluate major coastal plain, shallow marine, and river systems of northeastern South America, which serves to identify principal sources and controls of water and sediment flow into, through, and out of the Orinoco Delta.The regional analysis includes a summary of the geology, hydrodynamics, sediment dynamics, and geomorphic characteristics of the Orinoco drainage basin, river, and delta system. Because the Amazon River is a major source of sediment deposited along the Orinoco coast, we summarize Amazon water and sediment input to the northeastern South American littoral zone. We investigate sediment dynamics and geomorphology of the Guiana coast, where marine processes and Holocene history are similar to the Orinoco coast.Major factors controlling Orinoco Delta water and sediment dynamics include the pronounced annual flood discharge; the uneven distribution of water and sediment discharge across the delta plain; discharge of large volumes of water with low sediment concentrations through the Río Grande and Araguao distributaries; water and sediment dynamics associated with the Guayana littoral current along the northeastern South American coast; inflow of large volumes of Amazon sediment to the Orinoco coast; development of a fresh water plume seaward of Boca Grande; disruption of the Guayana Current by Trinidad, Boca de Serpientes, and Gulf of Paria; and the constriction at Boca de Serpientes.  相似文献