求解非线性有限元方程的弧长法及在工程稳定分析中的应用

本文讨论了求解非线性有限元方程弧长法的基本原理及具体实施,并应用于压杆及滑块的稳定性分析。由于弧长法具有确定并通过结构临界应力状态的临界荷载值,因此可以应用于工程稳定性分析。算例表明,弧长法确定的临界荷载值是令人满意的。     

钱塘江涌潮简析与预报

根据１９９１年观测资料，仑前潮位站出现涌潮１８４次，涌潮次数多少与江道地形变迁及上游下泄流量大小有关。涌潮高度在１．２－２．２ｍ之间，与涨潮潮差成正比。涌潮潮时预报方法有传播时间法和隔日滞后时间法。涌潮高度的预报，可根据当天涌潮高度预测后一天涌潮高度，也可根据下游站的涌潮高度预报上游站的涌潮高度。     

全球月平均高度距平场正斜压性的分析(I)--相关系数分布

利用欧洲中心全球客观分析的7层月平均位势高度距平资料,分别计算了相同格点上12-2月和6-8月各层高度距平之间的同时相关分布。结果表明:全球月平均位势高度距平场的正压、斜压性随地理区域变化很大,并有较明显的季节变化。其中12-2月对流层下部大气环流距平场在海洋上空有较好的相当正压性,在大陆上空正压性较差;对流层上部大气环流异常的正、斜压性分布与下部不同,赤道附近地区是相关系数的高值区,副热带地区主要是低值区;在对流层下部与上部大气环流距平场的相关系数分布图上,海洋上空并不总是高值区,在热带东太平洋区域就出现最强的负相关中心。与6-8月的相关系数分布型比较发现:特别明显的季节变化在非洲大陆和热带印度洋区域,12-2月为强正压区,6-8月为强斜压区。     

精确高程异常的确定

本文在顾及局部地形改正、椭球改正及大气改正的情况下,采用实测数据,应用Meissel方法和Wenzel频谱分析方法,对某盆地边缘的高程异常进行了实际计算。并将计算结果同多普勒高程异常进行了比较,证明结果是良好的。此外还对我国精确高程异常的确定提出了一些建议。     

Some engineering characteristics of a compacted lateritic residual soil

Summary In many parts of the world, particularly in humid tropical regions, residual soils are abundant. In this paper the suitability of a residual lateritic soil as a construction material is investigated, with respect to its strength and compaction characteristics. In comparison with other typical construction fills available in Southeast Asia, compacted lateritic soils produce excellent shear strengths and CBR values. However, the brittleness and tensile cracking of this compacted material become enhanced on the dry side of the optimum moisture content, or if excessive compaction is imparted. Nevertheless, at a moisture content of 2% wetter than the optimum, the tensile mode of failure is suppressed and the lateritic fills become ideally suited for the construction of high embankments and impervious dam cores.     

储层毛细管压力曲线在东海油气储量计算中的应用

本文阐述了利用储层毛细管压力曲线计算含油炮和度的方法,该方法在东海油气储量计算中取得良好的结果。     

论三角水准测量方法

三角水准测量是近年来发展起来的一类高程测量方法,目前国外主要通过实验来研究三角水准测量取代精密水准测量的可行性。本文根据我国的具体情况,从理论上分析以三角水准测量代替三等水准测量的可行性,并通过野外试验得到了一些有益的结论。     

The granulometrical characteristics of a slowly-moving dust cloud

A torn-up road offered the opportunity to sample a dust cloud continuously at different heights during a time interval of 51 hours. In particular the granulometrical characteristics of the dust caught were investigated. It appears that if the air layer in the vicinity of a dust cloud is not too turbulent, the cloud will be clearly granulometrically stratified. The coarse material moves chiefly at the bottom of the cloud, whereas the fine material will occur both at the bottom and at the top. The experiment also shows that the higher the dust in the cloud, the worse it is sorted. Above a critical height, however, the degree of sorting increases again. The variation of the mean dust diameter d₅₀, as a function of the height z, can be expressed in a simple semi-logarithmic equation. The variation of the dust quantity G, as a function of the height z, can also be expressed in a semi-logarithmic form but the correlation is higher when a power equation is used. The ratio of fine silt to coarse silt seems to vary parabolically with height. One can only speak of an optimal transport height in the case of particles > 16 μm. For finer particles, the turbulence of a normal air stream is usually high enough to carry the particles anywhere in the dust cloud, so that one can no longer speak of an optimal transport height. The granulometrical border between aeolian transport in saltation and aeolian transport in suspension lies, according to the results of the experiment, at a diameter of about 63 μm.     

Growth Of The Summer Daytime Convective Boundary Layer At Anand

The heights of the daytime convective boundary layer (CBL), computed by a one-dimensional model for a bare soil surface at a semi-arid station,Anand, during the dry and hot summer month of May 1997, are presented. As input, the model requires surface heat flux, friction velocity and air temperature as functions of time. Temperature data at the one-metre level from a tower and sonic anemometer data at 9.5 m collected during the period 13–17 May 1997 in the Land Surface Processes Experiment (LASPEX-97) are used to compute hourly values of surface heat flux, friction velocity and Obukhov length following the operational method suggested by Holtslag and Van Ulden [J. Climate Appl. Meteorol. 22,517–529 (1983)]. The model has been tested with different values for the potential temperature gradient ( ) above the inversion. The model-estimated CBL heights comparefavourably with observed heights obtained from radiosonde ascents.     

吉林腰英台油田油水分布特征及成因探讨

腰英台油田是东北地区新发现的油田，目前刚开始勘探开发，在勘探开发初期遇到不少问题。其中之一是开采时高含水：就油田的实际油水分布特征进行了分析，分析油水同出的可能原因，认为这是受油藏储层物性及构造幅度和实际油柱高度的影响，由于储层低孔、特低渗。实际构造幅度低，实际油柱高度大多低于油藏产纯油所需的油柱高度，致使油藏大都处于油水过渡带。故开采时多含水，油水同出。根据这一分析，认为进一步的油气勘探重点考虑西部水下冲积扇的有利部位。此处储层物性好，有利于接受更多油源。