上海淤泥质潮滩潮锋作用及其形成机制初步探讨*

本文具体讨论了上海淤泥质潮滩的潮锋作用过程,定性给出了潮锋的形成机制,认为潮锋作用及其水体高含沙量现象的本质在于“潮锋带水体水流加速效应”,即,由于潮滩坡面变化平缓的特殊性,涨潮水体前锋沿程存在着一持续时间可达数十分钟的水流加速过程.最后,本文初步探讨了潮锋作用在滩面塑造过程中的地位,并重新定义了潮锋作用的内容.     

Fluidization and representative wave transformation on muddy beds

Irregular wave-induced mud fluidization and wave spectrum transformation on muddy profiles are studied through representative wave technique. The constitutive equations of visco-elastic model are adopted for the rheological behavior of fluid mud, while the behavior of stationary mud is assumed to be elastic. A set of representative waves are employed to investigate wave–mud interaction. The results are verified using real field data. Comparing the performance of common representative waves, it is concluded that the phenomena can be better predicted by root mean square wave.     

Two-phase hydrodynamic and sediment transport modeling of wave-generated sheet flow

This numerical investigation was carried out to advance mechanistic understanding of sediment transport under sheet flow conditions. An Euler–Euler coupled two-phase flow model was developed to simulate fluid–sediment oscillatory sheet flow. Since the concentration of sediment particles is high in such flows, the kinematics of the fluid and sediment phases are strongly coupled. This model includes interaction forces, intergranular stresses and turbulent stress closure. Each phase was modeled via the Reynolds-Averaged Navier–Stokes equations, with interphase momentum conservation accounting for the interaction between the phases. The generation and transformation of turbulence was modeled using the two-equation k–ε$k''–''\epsilon$ turbulence model. Concentration and sediment flux profiles were compared with experimental data for sheet flow conditions considering both symmetric and asymmetric oscillatory flows. Sediment and fluid velocity variations, concentration profiles, sediment flux and turbulence parameters of wave-generated sheet flow were studied numerically with a focus on sediment transport characteristics. In all applications, the model predictions compared well with the experimental data. Unlike previous investigations in which the flow is driven by a horizontal pressure gradient, the present model solves the Navier–Stokes equations under propagating waves. The model’s ability to predict sediment transport under oscillatory sheet flow conditions underscores its potential for understanding the evolution of beach morphology.     

EXPERIMENTAL STUDY ON FALL VELOCITY OF NON-UNIFORM SEDIMENT IN FLOWING WATER

I INTRODUCTIONThe settlement of particles in fluid has been studied in many fields such as hydraulics, metallurgy andchemistry since the middle of 19 century because of its great importance. Although the settlement ofsingle particle and group settling velocity of uniform particles in still water are relatively well-studied, yetthe settlement of non-uniform particles in flowing water lacks understanding. For instance, Cunningham(1910), Richardson (1954) and Batchelor (1972), have obtained…     

近44年无锡寒潮天气变化特征分析

利用无锡市1959～2002年共44a的逐日最低气温资料,分析了无锡寒潮发生的特点.分析结果表明:无锡寒潮的年发生次数有线性减少趋势;寒潮减少主要发生在10月、12月、4月.分年代看,从20世纪60年代到80年代逐年代减少,但90年代又增多.寒潮减少与降温幅度减小、最低气温升高有关,其中最低气温升高是其主要影响因素.特征区域的500 hPa高度场偏高是寒潮发生次数减少的直接原因.最后,针对多寒潮年和少寒潮年的环流特点,给出了500 hPa典型距平场特征.     

钾盐矿床的物质来源和成矿机制

讨论钾及其有关物质的理化性质和地化行为，钾盐的物质来源，盐卤的变质、结晶分异、成矿条件和机制。富钾热液是形成钾盐矿床的重要物质来源之一。矿物岩石流体包裹体的富钾成分、富钾热泉、富钾盐湖均是寻找钾盐矿床的重要指示。     

兰州市冬季空气污染的天气成因分析及浓度预报

兰州是全国冬季大气污染最严重的城市之一 ,通过对污染与天气形势的分析 ,给出了影响冬季兰州污染的天气分型 ;对 3种主要空气污染物TSP、SO2 、NOX 浓度值与同期表征逆温特征的逆温参数及地面气象要素作了统计分析 ,结果表明 :(1)污染物浓度与逆温层厚度呈显著正相关 ;(2 )污染物浓度与平均温度、能见度、风速、总云量、相对湿度成负相关 ,与温差、气压成正相关。最后针对不同天气分型 ,给出了冬半年兰州污染物浓度预报方程 ,经检验预报效果良好     

吉林省夹皮沟—金城洞绿岩区中金矿床形成的物理化学条件

作者应用气液包裹体研究和热力学方法讨论了吉林省夹皮沟—金城洞绿岩区中金矿床形成的物理化学条件,分别确定了Ⅰ矿田(石(?)沟旷田)、Ⅱ矿田(夹皮沟矿田)和Ⅲ矿田(金城洞矿田)的成矿T、P、pH、Eh、fs_2、fo_2、fco_2及成矿溶液性质、成分类型、主要成矿离子Pb~(2+)、Zn~(2+)、Fe~(2+)、[AuS_3]~(3-)的浓度。     

Heavy metal concentrations (Cd,Cu and Pb) in five aquatic plant species in Tasik Chini,Malaysia

The purpose of this study was to determine the levels of heavy metals namely cadmium (Cd), copper (Cu) and lead (Pb) in the five aquatic plants. For this purpose, the concentration of heavy metals were measured in water and in the five aquatic plant species, Lepironia articulata, Pandanus helicopus, Scirpus grossus, Cabomba furcata and Nelumbo nucifera, in 15 sites from Tasik Chini. The concentrations were different among the plant species as well as among the parts of plants. The highest concentration of heavy metals among the aquatic plants and plant parts was found in the roots of S. grossus. The concentrations of Cd in the leaves and stems of submerged aquatic plant, C. furcata, were higher than concentration of Cd in the leaves and stems of emergent aquatic plant and floating leaf plant. The concentration of Cu in the stem of C. furcata was greater than that in the leaf, while the concentration of Cd was more in the leaf than in the stem. The heavy metal contents of the aquatic plants were in descending order of Pb > Cu > Cd. The metal concentration quotient of leaves/roots and stems/roots (ML/MR and MS/MR) were calculated. The highest internal translocation was found in P. helicopus, while the lowest internal translocation was found in S. grossus.     

聚合物驱油浓度与粘度的研究

本文对聚全物驱油试验获得聚合物溶液的方式和聚合物浓度、粘度的测定进行了研究和比较，得到了辉锐公司自动混配装置中的可编程控制器设置浓度的修正值。此研究对控制聚合物浓度稳定、准确地注入和聚合物驱油效果的评价具有实际价值。